Bio


Dr. Liao is a Professor of Medicine and co-Director of Stanford Cardiac Amyloid Center. The major goal of her research program focuses on understanding the mechanisms that underlie the pathophysiology of heart failure and developing novel treatments to combat this process. Her laboratory has played an international leading role in the study of amyloid light chain (AL) cardiomyopathy, a rare and fatal form of cardiovascular disease. We have described the underlying pathophysiologic basis for amyloid cardiomyopathy and found that the circulating amyloidogenic light chain proteins that characterize this disease directly result in a specific cardiotoxic response. Consequently, our research work has redefined AL cardiomyopathy and has raised new treatment approaches. More recently, her research efforts have expanded to include transthyretin (ATTR) cardiac amyloidosis.

In line with her goal of revealing novel therapeutic strategies for patients with cardiovascular disease, our efforts have also focused on characterizing and harnessing endogenous cardiac regenerative mechanisms. Her laboratory initially demonstrated the therapeutic potential of exogenous primitive muscle cells delivered to the injured heart. This work was among the earliest milestones in the field and served as the basis for an international trial of cell-based therapy. Subsequently, Liao lab identified and characterized a population of cardiac progenitor cells and its relationship and dynamic activity following cardiac injury in the adult heart. Her laboratory aims to reveal the molecular mechanisms regulating the endogenous regenerative capacity of the heart and to harness such repair mechanisms for the treatment of cardiovascular disease. Dr. Liao has lectured extensively on both amyloid cardiomyopathy and stem cell biology, and have maintained a history of independent NIH funding in these areas for more than two decades.

Over the course of her academic career, she has taken the greatest pride in mentoring the next generation of scientists. Dr. Liao has had the privilege to supervise several dozen students, postdoctoral fellows, and junior faculty, many of whom have gone on to independent academic careers at the highest institutions. Her contribution to the advancement of scientific knowledge also includes lecturing at various university and academic institutions as well as at scores of conferences and symposia locally, nationally, and internationally.

Administrative Appointments


  • Co-Director, Stanford Amyloid Center (2017 - Present)

Boards, Advisory Committees, Professional Organizations


  • Associate Director, Cardiac Muscle Research Laboratory, Boston University School of Medicine (1997 - 2003)
  • Co-Director, Cardiac Muscle Research Laboratory, Boston University School of Medicine (2003 - 2005)
  • Director, Integrated Cardiovascular Physiology Laboratory, Department of Medicine, Boston University School of Medicine (2004 - 2005)
  • Director, Cardiac Muscle Research Laboratory, Department of Medicine, Brigham and Women’s Hospital (2005 - Present)
  • Director, Brigham and Women’s Hospital Cardiovascular Physiology Core (2010 - Present)
  • Vice Chair, Basic Cardiovascular Sciences Council, American Heart Association (2014 - 2016)
  • Chair, Basic Cardiovascular Sciences Council, American Heart Association (2016 - 2018)
  • Co-Director, Stanford Amyloid Center (2017 - Present)
  • Director, Brigham and Women’s Hospital Physiological NMR Core (2017 - Present)

Professional Education


  • Postdoc, Brigham and Women's Hospital and Harvard Medical School, Myocardial energetics (1991)
  • Postdoc, Beth Israel Hospital and Harvard Medical School, Cardiac physiology (1990)
  • M.A. (hon), Harvard University, Biomedical Science (2015)
  • PhD, University of Alabama at Birmingham, Biophysics (1990)

Stanford Advisees


All Publications


  • The bone marrow--cardiac axis of myocardial regeneration. Progress in cardiovascular diseases Liao, R., Pfister, O., Jain, M., Mouquet, F. ; 50 (1): 18–30

    Abstract

    Congestive heart failure remains the leading cause of morbidity and mortality in the developed world. Current therapies do not address the underlying pathophysiology of this disease, namely, the progressive loss of functional cardiomyocytes. The notion of repairing or regenerating lost myocardium via cell-based therapies remains highly appealing. The recent identification of adult stem cells, including both cardiac stem/progenitor cells and bone marrow stem cells, has triggered an explosive interest in using these cells for physiologically relevant cardiomyogenesis. Enthusiasm for cardiac regeneration via cell therapy has further been fueled by the many encouraging reports in both animals and human studies. Further intensive research in basic science and clinical arenas are needed to make this next great frontier in cardiovascular regenerative medicine a reality. In this review, we focus on the role of bone marrow-derived stem cells and cardiac stem/progenitor cells in cardiomyocyte homeostasis and myocardial repair and regeneration, as well as provide a brief overview of current clinical trials using cell-based therapeutic approaches in patients with heart disease.

    View details for PubMedID 17631435

    View details for PubMedCentralID PMC2096729

  • Improved Quantification of CardiacAmyloid Burden in SystemicLight ChainAmyloidosis: Redefining Early Disease? JACC. Cardiovascular imaging Cuddy, S. A., Bravo, P. E., Falk, R. H., El-Sady, S., Kijewski, M. F., Park, M., Ruberg, F. L., Sanchorawala, V., Landau, H., Yee, A. J., Bianchi, G., Di Carli, M. F., Cheng, S., Jerosch-Herold, M., Kwong, R. Y., Liao, R., Dorbala, S. 2020

    Abstract

    OBJECTIVES: The purpose of this study was to determine phenotypes characterizing cardiac involvement in AL amyloidosis by using direct (fluorine-18-labeled florbetapir {[18F]florbetapir} positron emission tomography [PET]/computed tomography) and indirect (echocardiography and cardiac magnetic resonance [CMR]) imaging biomarkers of AL amyloidosis.BACKGROUND: Cardiac involvement in systemic light chain amyloidosis (AL) is the main determinant of prognosis and, therefore, guides management. The hypothesis of this study was that myocardial AL deposits and expansion of extracellular volume (ECV) could be identified before increases in N-terminal pro-B-type natriuretic peptide or wall thickness.METHODS: A total of 45 subjects were prospectively enrolled in 3 groups: 25 with active AL amyloidosis with cardiacinvolvement (active-CA), 10 with active AL amyloidosis without cardiac involvement by conventional criteria(active-non-CA), and 10 with AL amyloidosis with cardiac involvement in remission for at least 1 year (remission-CA). All subjects underwent echocardiography, CMR, and [18F]florbetapir PET/CT to evaluate cardiac amyloid burden.RESULTS: The active-CA group demonstrated the largest myocardial AL amyloid burden, quantified by [18F]florbetapir retention index (RI) 0.110 (interquartile range [IQR]: 0.078 to 0.139) min-1, and the lowest cardiac function by global longitudinal strain (GLS), median GLS-11% (IQR:-8% to-13%). The remission-CA group had expanded extracellular volume (ECV) and [18F]florbetapir RI of 0.097 (IQR: 0.070, 0.124min-1), and abnormal GLS despite hematologic remission for >1 year. The active-non-CA cohort had evidence of cardiac amyloid deposition by advanced imaging metrics in 50% of the subjects; cardiac involvement was identified by late gadolinium enhancement in 20%, elevated ECV in 20%, and elevated [18F]florbetapir RI in 50%.CONCLUSIONS: Evidence of cardiac amyloid infiltration was found based on direct and indirect imaging biomarkers in subjects without CA by conventional criteria. The findings from [18F]florbetapir PET imaging provided insight into the preclinical disease process and on the basis of interpretation of expanded ECV on CMR and have important implications for future research and clinical management of AL amyloidosis. (Molecular Imaging of Primary Amyloid Cardiomyopathy [MICA]; NCT02641145).

    View details for DOI 10.1016/j.jcmg.2020.02.025

    View details for PubMedID 32417333

  • Localized Antileptin Therapy Prevents Aortic Root Dilatation and Preserves Left Ventricular Systolic Function in a Murine Model of Marfan Syndrome. Journal of the American Heart Association Fisch, S., Bachner-Hinenzon, N., Ertracht, O., Guo, L., Arad, Y., Ben-Zvi, D., Liao, R., Schneiderman, J. 2020: e014761

    Abstract

    Background Marfan syndrome (MFS) is a genetically transmitted connective tissue disorder characterized by aortic root dilatation, dissection, and rupture. Molecularly, MFS pathological features have been shown to be driven by increased angiotensin II in the aortic wall. Using an angiotensin II-driven aneurysm mouse model, we have recently demonstrated that local inhibition of leptin activity restricts aneurysm formation in the ascending and abdominal aorta. As we observed de novo leptin synthesis in the ascending aortic aneurysm wall of patients with MFS, we hypothesized that local counteracting of leptin activity in MFS may also prevent aortic cardiovascular complications in this context. Methods and Results Fbn1C1039G/+ mice underwent periaortic application of low-dose leptin antagonist at the aortic root. Treatment abolished medial degeneration and prevented increase in aortic root diameter (P<0.001). High levels of leptin, transforming growth factor beta1, Phosphorylated Small mothers against decapentaplegic 2, and angiotensin-converting enzyme 1 observed in saline-treated MFS mice were downregulated in leptin antagonist-treated animals (P<0.01, P<0.05, P<0.001, and P<0.001, respectively). Leptin and angiotensin-converting enzyme 1 expression levels in left ventricular cardiomyocytes were also decreased (P<0.001) and coincided with prevention of left ventricular hypertrophy and aortic and mitral valve leaflet thickening (P<0.01 and P<0.05, respectively) and systolic function preservation. Conclusions Local, periaortic application of leptin antagonist prevented aortic root dilatation and left ventricular valve remodeling, preserving left ventricular systolic function in an MFS mouse model. Our results suggest that local inhibition of leptin may constitute a novel, stand-alone approach to prevent MFS aortic root aneurysms and potentially other similar angiotensin II-driven aortic pathological features.

    View details for DOI 10.1161/JAHA.119.014761

    View details for PubMedID 32378446

  • High-Frequency Ultrasound Echocardiography to Assess Zebrafish Cardiac Function. Journal of visualized experiments : JoVE Evangelisti, A., Schimmel, K., Joshi, S., Shah, K., Fisch, S., Alexander, K. M., Liao, R., Morgado, I. 2020

    Abstract

    The zebrafish (Danio rerio) has become a very popular model organism in cardiovascular research, including human cardiac diseases, largely due to its embryonic transparency, genetic tractability, and amenity to rapid, high-throughput studies. However, the loss of transparency limits heart function analysis at the adult stage, which complicates modeling of age-related heart conditions. To overcome such limitations, high-frequency ultrasound echocardiography in zebrafish is emerging as a viable option. Here, we present a detailed protocol to assess cardiac function in adult zebrafish by non-invasive echocardiography using high-frequency ultrasound. The method allows visualization and analysis of zebrafish heart dimension and quantification of important functional parameters, including heart rate, stroke volume, cardiac output, and ejection fraction. In this method, the fish are anesthetized and kept underwater and can be recovered after the procedure. Although high-frequency ultrasound is an expensive technology, the same imaging platform can be used for different species (e.g., murine and zebrafish) by adapting different transducers. Zebrafish echocardiography is a robust method for cardiac phenotyping, useful in the validation and characterization of disease models, particularly late-onset diseases; drug screens; and studies of heart injury, recovery, and regenerative capacity.

    View details for DOI 10.3791/60976

    View details for PubMedID 32225163

  • Mitochondrial MUL1 E3 ubiquitin ligase regulates Hypoxia Inducible Factor (HIF-1alpha) and metabolic reprogramming by modulating the UBXN7 cofactor protein. Scientific reports Cilenti, L., Di Gregorio, J., Ambivero, C. T., Andl, T., Liao, R., Zervos, A. S. 2020; 10 (1): 1609

    Abstract

    MUL1 is a multifunctional E3 ubiquitin ligase anchored in the outer mitochondrial membrane with its RING finger domain facing the cytoplasm. MUL1 participates in various biological pathways involved in apoptosis, mitochondrial dynamics, and innate immune response. The unique topology of MUL1 enables it to "sense" mitochondrial stress in the intermembrane mitochondrial space and convey these signals through the ubiquitination of specific cytoplasmic substrates. We have identified UBXN7, the cofactor protein of the CRL2VHL ligase complex, as a specific substrate of MUL1 ligase. CRL2VHL ligase complex regulates HIF-1alpha protein levels under aerobic (normoxia) or anaerobic (hypoxia) conditions. Inactivation of MUL1 ligase leads to accumulation of UBXN7, with concomitant increase in HIF-1alpha protein levels, reduction in oxidative phosphorylation, and increased glycolysis. We describe a novel pathway that originates in the mitochondria and operates upstream of the CRL2VHL ligase complex. Furthermore, we delineate the mechanism by which the mitochondria, through MUL1 ligase, can inhibit the CRL2VHL complex leading to high HIF-1alpha protein levels and a metabolic shift to glycolysis under normoxic conditions.

    View details for DOI 10.1038/s41598-020-58484-8

    View details for PubMedID 32005965

  • Modeling Secondary Iron Overload Cardiomyopathy with Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Cell reports Rhee, J. W., Yi, H., Thomas, D., Lam, C. K., Belbachir, N., Tian, L., Qin, X., Malisa, J., Lau, E., Paik, D. T., Kim, Y., Choi, B. S., Sayed, N., Sallam, K., Liao, R., Wu, J. C. 2020; 32 (2): 107886

    Abstract

    Excessive iron accumulation in the heart causes iron overload cardiomyopathy (IOC), which initially presents as diastolic dysfunction and arrhythmia but progresses to systolic dysfunction and end-stage heart failure when left untreated. However, the mechanisms of iron-related cardiac injury and how iron accumulates in human cardiomyocytes are not well understood. Herein, using human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), we model IOC and screen for drugs to rescue the iron overload phenotypes. Human iPSC-CMs under excess iron exposure recapitulate early-stage IOC, including oxidative stress, arrhythmia, and contractile dysfunction. We find that iron-induced changes in calcium kinetics play a critical role in dysregulation of CM functions. We identify that ebselen, a selective divalent metal transporter 1 (DMT1) inhibitor and antioxidant, could prevent the observed iron overload phenotypes, supporting the role of DMT1 in iron uptake into the human myocardium. These results suggest that ebselen may be a potential preventive and therapeutic agent for treating patients with secondary iron overload.

    View details for DOI 10.1016/j.celrep.2020.107886

    View details for PubMedID 32668256

  • Harnessing Cardiac Regeneration as a Potential Therapeutic Strategy for AL Cardiac Amyloidosis. Current cardiology reports Joshi, S., Evangelisti, A., Liao, R., Alexander, K. M. 2020; 22 (1): 1

    Abstract

    Cardiac regeneration has received much attention as a possible means to treat various forms of cardiac injury. This review will explore the field of cardiac regeneration by highlighting the existing animal models, describing the involved molecular pathways, and discussing attempts to harness cardiac regeneration to treat cardiomyopathies.Light chain cardiac amyloidosis is a degenerative disease characterized by progressive heart failure due to amyloid fibril deposition and light chain-mediated cardiotoxicity. Recent findings in a zebrafish model of light chain amyloidosis suggest that cardiac regenerative confers a protective effect against this disease. Cardiac regeneration remains an intriguing potential tool for treating cardiovascular disease. Degenerative diseases, such as light chain cardiac amyloidosis, may be particularly suited for therapeutic interventions that target cardiac regeneration. Further studies are needed to translate preclinical findings for cardiac regeneration into effective therapies.

    View details for DOI 10.1007/s11886-020-1252-3

    View details for PubMedID 31932992

  • Natural Compound Library Screening Identifies New Molecules for the Treatment of Cardiac Fibrosis and Diastolic Dysfunction. Circulation Schimmel, K., Jung, M., Foinquinos, A., San José, G., Beaumont, J., Bock, K., Grote-Levi, L., Xiao, K., Bär, C., Pfanne, A., Just, A., Zimmer, K., Ngoy, S., López, B., Ravassa, S., Samolovac, S., Janssen-Peters, H., Remke, J., Scherf, K., Dangwal, S., Piccoli, M. T., Kleemiss, F., Kreutzer, F. P., Kenneweg, F., Leonardy, J., Hobuß, L., Santer, L., Do, Q. T., Geffers, R., Braesen, J. H., Schmitz, J., Brandenberger, C., Müller, D. N., Wilck, N., Kaever, V., Bähre, H., Batkai, S., Fiedler, J., Alexander, K. M., Wertheim, B. M., Fisch, S., Liao, R., Diez, J., González, A., Thum, T. 2020

    Abstract

    Background: Myocardial fibrosis is a hallmark of cardiac remodeling and functionally involved in heart failure (HF) development, a leading cause of deaths worldwide. Clinically there is no therapeutic strategy available that specifically attenuates maladaptive responses of cardiac fibroblasts, the effector cells of fibrosis in the heart. Therefore, we aimed at the development of novel anti-fibrotic therapeutics based on natural-derived substance library screens for the treatment of cardiac fibrosis. Methods: Anti-fibrotic drug candidates were identified by functional screening of 480 chemically diverse natural compounds in primary human cardiac fibroblasts (HCFs), subsequent validation and mechanistic in vitro and in vivo studies. Hits were analyzed for dose-dependent inhibition of proliferation of HCFs, for modulation of apoptosis and extracellular matrix expression. In vitro findings were confirmed in vivo, using an angiotensin II (Ang II)-mediated murine model of cardiac fibrosis in both preventive and therapeutic settings, as well as in the Dahl salt sensitive rat model. To investigate the mechanism underlying the anti-fibrotic potential of the lead compounds, treatment-dependent changes in the noncoding RNAome in primary HCFs were analyzed by RNA-deep sequencing. Results: High-throughput natural compound library screening identified 15 substances with antiproliferative effects in HCFs. Using multiple in vitro fibrosis assays and stringent selection algorithms we identified the steroid bufalin (from Chinese toad venom) and the alkaloid lycorine (from Amaryllidaceae species) to be effective anti-fibrotic molecules both in vitro and in vivo leading to improvement in diastolic function in two hypertension-dependent rodent models of cardiac fibrosis. Administration at effective doses did not change plasma damage markers nor the morphology of kidney and liver, providing first toxicological safety data. By next-generation sequencing we identified the conserved microRNA (miR) miR-671-5p and downstream the antifibrotic selenoprotein P1 (SEPP1) as common effectors of the anti-fibrotic compounds. Conclusions: We identified the molecules bufalin and lycorine as drug candidates for therapeutic applications in cardiac fibrosis and diastolic dysfunction.

    View details for DOI 10.1161/CIRCULATIONAHA.119.042559

    View details for PubMedID 31948273

  • Outcomes in Patients With Cardiac Amyloidosis Undergoing Heart Transplantation. JACC. Heart failure Barrett, C. D., Alexander, K. M., Zhao, H., Haddad, F., Cheng, P., Liao, R., Wheeler, M. T., Liedtke, M., Schrier, S., Arai, S., Weisshaar, D., Witteles, R. M. 2020

    Abstract

    The purpose of this study is to report outcomes after heart transplantation in patients with cardiac amyloidosis based on a large single-center experience.Cardiac amyloidosis causes significant morbidity and mortality, often leading to restrictive cardiomyopathy, progressive heart failure, and death. Historically, heart transplantation outcomes have been worse in patients with cardiac amyloidosis compared with other heart failure populations, in part due to the systemic nature of the disease. However, several case series have suggested that transplantation outcomes may be better in the contemporary era, likely in part due to the availability of more effective light chain suppressive therapies for light chain amyloidosis.This study examined all patients seen between 2004 and 2017, either at the Stanford University Medical Center or the Kaiser Permanente Santa Clara Medical Center, who were diagnosed with cardiac amyloidosis and ultimately underwent heart transplantation. This study examined pre-transplantation characteristics and post-transplantation outcomes in this group compared with the overall transplantation population at our center.During the study period, 31 patients (13 with light chain amyloidosis and 18 with transthyretin [ATTR] amyloidosis) underwent heart transplantation. Patients with ATTR amyloidosis were older, were more likely to be male, had worse baseline renal function, and had longer waitlist times compared with both patients with light chain amyloidosis and the overall transplantation population. Post-transplantation, there were no differences in post-operative bleeding, renal failure, infection, rejection, or malignancy. There was no significant difference in mortality between patients who underwent heart transplantation for amyloid cardiomyopathy and patients who underwent heart transplantation for all other indications.In carefully selected patients with cardiac amyloidosis, heart transplantation can be an effective therapeutic option with outcomes similar to those transplanted for other causes of heart failure.

    View details for DOI 10.1016/j.jchf.2019.12.013

    View details for PubMedID 32387068

  • Gene Signatures to Distinguish Amyloid Cardiomyopathy Risk in Multiple Myeloma Patients Jha, A., Morgado, I., Lee, D. J., Alexander, K., Tsai, C., Schimmel, K., Ward, J., Witteles, R., Liedtke, M., Liao, R., Dangwal, S. LIPPINCOTT WILLIAMS & WILKINS. 2019
  • Prenatal Exposure of Cigarette Smoke Impacts Cardiac Regeneration Schimmel, K., Morgado, I., Tsai, C., Evangelisti, A., Fisch, S., Ngoy, S., Lee, D., Dangwal, S., Alexander, K., Ward, J. E., Liao, R. LIPPINCOTT WILLIAMS & WILKINS. 2019
  • Zebrafish model of amyloid light chain cardiotoxicity: regeneration versus degeneration AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY Mishra, S., Joshi, S., Ward, J. E., Buys, E. P., Mishra, D., Mishra, D., Morgado, I., Fisch, S., Lavatelli, F., Merlini, G., Dorbala, S., MacRae, C. A., Liao, R. 2019; 316 (5): H1158–H1166
  • Zebrafish model of amyloid light chain cardiotoxicity: regeneration vs degeneration. American journal of physiology. Heart and circulatory physiology Mishra, S., Joshi, S., Ward, J. E., Buys, E. P., Mishra, D., Mishra, D., Morgado, I., Fisch, S., Lavatelli, F., Merlini, G., Dorbala, S., MacRae, C. A., Liao, R. 2019

    Abstract

    Cardiac dysfunction is the most frequent cause of morbidity and mortality in immunoglobulin light chain (AL) amyloidosis. Previously published transgenic animal models of AL amyloidosis have not recapitulated the key phenotype of cardiac dysfunction seen in AL amyloidosis which has limited our understanding of the disease mechanisms in vivo, as well as the development of targeted AL therapeutics. We have developed a transgenic zebrafish model in which a AL patient-derived lambda light chain (LC) is conditionally expressed in the liver under the control of UAS-Gal4 enhancer system. Circulating LC levels of 125 g/ml in these transgenic zebrafish are comparable to median pathologic serum LC levels. Functional analysis links abnormal contractile function with evidence of cellular and molecular proteotoxicity in the heart, including increased cell death and autophagy. However, despite pathologic and functional phenotypes analogous to human AL, the lifespan of the transgenic fish is comparable to control fish without the expressed AL-LC transgene. Nuclear labeling experiments suggest increased cardiac proliferation in the transgenic fish, which can be counteracted by treatment with a small molecule proliferation inhibitor leading to increased zebrafish mortality due to cardiac apoptosis and functional deterioration. This transgenic zebrafish model provides a platform to further study underlying AL disease mechanisms in vivo.

    View details for PubMedID 30875258

  • Convergences of Life Sciences and Engineering in Understanding and Treating Heart Failure. Circulation research Berry, J. L., Zhu, W., Tang, Y. L., Krishnamurthy, P., Ge, Y., Cooke, J. P., Chen, Y., Garry, D. J., Yang, H., Rajasekaran, N. S., Koch, W. J., Li, S., Domae, K., Qin, G., Cheng, K., Kamp, T. J., Ye, L., Hu, S., Ogle, B. M., Rogers, J. M., Abel, E. D., Davis, M. E., Prabhu, S. D., Liao, R., Pu, W. T., Wang, Y., Ping, P., Bursac, N., Vunjak-Novakovic, G., Wu, J. C., Bolli, R., Menasche, P., Zhang, J. 2019; 124 (1): 161–69

    Abstract

    On March 1 and 2, 2018, the National Institutes of Health 2018 Progenitor Cell Translational Consortium, Cardiovascular Bioengineering Symposium, was held at the University of Alabama at Birmingham. Convergence of life sciences and engineering to advance the understanding and treatment of heart failure was the theme of the meeting. Over 150 attendees were present, and >40 scientists presented their latest work on engineering human functional myocardium for disease modeling, drug development, and heart failure research. The scientists, engineers, and physicians in the field of cardiovascular sciences met and discussed the most recent advances in their work and proposed future strategies for overcoming the major roadblocks of cardiovascular bioengineering and therapy. Particular emphasis was given for manipulation and using of stem/progenitor cells, biomaterials, and methods to provide molecular, chemical, and mechanical cues to cells to influence their identity and fate in vitro and in vivo. Collectively, these works are profoundly impacting and progressing toward deciphering the mechanisms and developing novel treatments for left ventricular dysfunction of failing hearts. Here, we present some important perspectives that emerged from this meeting.

    View details for PubMedID 30605412

  • Alteration in ventricular pressure stimulates cardiac repair and remodeling. Journal of molecular and cellular cardiology Unno, K., Oikonomopoulos, A., Fujikawa, Y., Okuno, Y., Narita, S., Kato, T., Hayashida, R., Kondo, K., Shibata, R., Murohara, T., Yang, Y., Dangwal, S., Sereti, K. I., Yiling, Q., Johnson, K., Jha, A., Sosnovik, D. E., Fann, Y., Liao, R. 2019

    Abstract

    The mammalian heart undergoes complex structural and functional remodeling to compensate for stresses such as pressure overload. While studies suggest that, at best, the adult mammalian heart is capable of very limited regeneration arising from the proliferation of existing cardiomyocytes, how myocardial stress affects endogenous cardiac regeneration or repair is unknown. To define the relationship between left ventricular afterload and cardiac repair, we induced left ventricle pressure overload in adult mice by constriction of the ascending aorta (AAC). One week following AAC, we normalized ventricular afterload in a subset of animals through removal of the aortic constriction (de-AAC). Subsequent monitoring of cardiomyocyte cell cycle activity via thymidine analog labeling revealed that an acute increase in ventricular afterload induced cardiomyocyte proliferation. Intriguingly, a release in ventricular overload (de-AAC) further increases cardiomyocyte proliferation. Following both AAC and de-AAC, thymidine analog-positive cardiomyocytes exhibited characteristics of newly generated cardiomyocytes, including single diploid nuclei and reduced cell size as compared to age-matched, sham-operated adult mouse myocytes. Notably, those smaller cardiomyocytes frequently resided alongside one another, consistent with local stimulation of cellular proliferation. Collectively, our data demonstrate that adult cardiomyocyte proliferation can be locally stimulated by an acute increase or decrease of ventricular pressure, and this mode of stimulation can be harnessed to promote cardiac repair.

    View details for DOI 10.1016/j.yjmcc.2019.06.006

    View details for PubMedID 31220468

  • Quantitative [18F]florbetapir PET/CT may identify lung involvement in patients with systemic AL amyloidosis. European journal of nuclear medicine and molecular imaging Khor, Y. M., Cuddy, S., Harms, H. J., Kijewski, M. F., Park, M. A., Robertson, M., Hyun, H., Di Carli, M. F., Bianchi, G., Landau, H., Yee, A., Sanchorawala, V., Ruberg, F. L., Liao, R., Berk, J., Falk, R. H., Dorbala, S. 2019

    Abstract

    The clinical diagnosis of pulmonary involvement in individuals with systemic AL amyloidosis remains challenging. [18F]florbetapir imaging has previously identified AL amyloid deposits in the heart and extra-cardiac organs. The aim of this study is to determine quantitative [18F]florbetapir pulmonary kinetics to identify pulmonary involvement in individuals with systemic AL amyloidosis.We prospectively enrolled 58 subjects with biopsy-proven AL amyloidosis and 9 control subjects (5 without amyloidosis and 4 with ATTR cardiac amyloidosis). Pulmonary [18F]florbetapir uptake was evaluated visually and quantified as distribution volume of specific binding (Vs) derived from compartmental analysis and simpler semiquantitative metrics of maximum standardized uptake values (SUVmax), retention index (RI), and target-to-blood ratio (TBR).On visual analysis, pulmonary tracer uptake was absent in most AL subjects (40/58, 69%); 12% (7/58) of AL subjects demonstrated intense bilateral homogeneous tracer uptake. In this group, compared to the control group, Vs (median Vs 30-fold higher, 9.79 vs. 0.26, p < 0.001), TBR (median TBR 12.0 vs. 1.71, p < 0.001), and RI (median RI 0.310 vs. 0.033, p < 0.001) were substantially higher. Notably, the AL group without visually apparent pulmonary [18F]florbetapir uptake also demonstrated a > 3-fold higher Vs compared to the control group (median 0.99 vs. 0.26, p < 0.001). Vs was independently related to left ventricular SUVmax, a marker of cardiac AL deposition, but not to ejection fraction, a marker of cardiac dysfunction. Also, intense [18F]florbetapir lung uptake was not related to [11C]acetate lung uptake, suggesting that intense [18F]florbetapir lung uptake represents AL amyloidosis rather than heart failure.[18F]florbetapir PET/CT offers the potential to noninvasively identify pulmonary AL amyloidosis, and its clinical relevance warrants further study.

    View details for DOI 10.1007/s00259-019-04627-7

    View details for PubMedID 31807884

  • A single combination gene therapy treats multiple age-related diseases. Proceedings of the National Academy of Sciences of the United States of America Davidsohn, N., Pezzone, M., Vernet, A., Graveline, A., Oliver, D., Slomovic, S., Punthambaker, S., Sun, X., Liao, R., Bonventre, J. V., Church, G. M. 2019

    Abstract

    Comorbidity is common as age increases, and currently prescribed treatments often ignore the interconnectedness of the involved age-related diseases. The presence of any one such disease usually increases the risk of having others, and new approaches will be more effective at increasing an individual's health span by taking this systems-level view into account. In this study, we developed gene therapies based on 3 longevity associated genes (fibroblast growth factor 21 [FGF21], αKlotho, soluble form of mouse transforming growth factor-β receptor 2 [sTGFβR2]) delivered using adeno-associated viruses and explored their ability to mitigate 4 age-related diseases: obesity, type II diabetes, heart failure, and renal failure. Individually and combinatorially, we applied these therapies to disease-specific mouse models and found that this set of diverse pathologies could be effectively treated and in some cases, even reversed with a single dose. We observed a 58% increase in heart function in ascending aortic constriction ensuing heart failure, a 38% reduction in α-smooth muscle actin (αSMA) expression, and a 75% reduction in renal medullary atrophy in mice subjected to unilateral ureteral obstruction and a complete reversal of obesity and diabetes phenotypes in mice fed a constant high-fat diet. Crucially, we discovered that a single formulation combining 2 separate therapies into 1 was able to treat all 4 diseases. These results emphasize the promise of gene therapy for treating diverse age-related ailments and demonstrate the potential of combination gene therapy that may improve health span and longevity by addressing multiple diseases at once.

    View details for DOI 10.1073/pnas.1910073116

    View details for PubMedID 31685628

  • Mortality from Heart Failure and Dementia in the United States: CDC WONDER 1999-2016. Journal of cardiac failure Vuong, J. T., Jacob, S. A., Alexander, K. M., Singh, A., Liao, R., Desai, A. S., Dorbala, S. 2018

    Abstract

    Heart failure and dementia are diseases of the elderly that result in billions of dollars in annual healthcare expenditure. With the aging of the United States population, and increasing evidence of shared risk factors, there is a need to understand the conditions' shared contributions to nationwide mortality. The objectives of our study are to estimate the burden of mortality from heart failure and dementia and characterize the demographics of affected individuals.This is a retrospective study using National Vital Statistics Data from 1999-2016 provided by the Centers for Disease Control and ICD-10 codes for heart failure and dementia defined by the Medicare Chronic Conditions Data Warehouse. From 1999 to 2016, deaths contributed by heart failure and dementia totaled 214,706 and comprised 4.00% of all heart failure deaths and 9.04% of all dementia deaths. Women were more affected than men, with higher age-adjusted mortality rates (per 1,000,000 person-years): 38.67, 95% CI: 38.47-38.87 vs. 32.90, 95% CI: 32.65-33.15, p<0.001. Whites were affected more than Blacks, with age-adjusted mortality rates (per 1,000,000 person-years): 38.00, 95% CI: 37.83-38.16 vs. 31.06, 95% CI: 30.54-31.59, p<0.001. However, under the age of 65 years, higher crude mortality rates (per 1,000,000 person-years) were reported in men (0.20, 95% CI 0.18-0.22) compared with women (0.15, 95% CI 0.13-0.16, p<0.001).This study provides insight into temporal trends and nationwide mortality rates reported for heart failure and dementia. Our results suggest a disproportionate burden on populations over 85 years, Whites, and women.

    View details for PubMedID 30471348

  • Cardiac macrophages promote diastolic dysfunction. The Journal of experimental medicine Hulsmans, M., Sager, H. B., Roh, J. D., Valero-Muñoz, M., Houstis, N. E., Iwamoto, Y., Sun, Y., Wilson, R. M., Wojtkiewicz, G., Tricot, B., Osborne, M. T., Hung, J., Vinegoni, C., Naxerova, K., Sosnovik, D. E., Zile, M. R., Bradshaw, A. D., Liao, R., Tawakol, A., Weissleder, R., Rosenzweig, A., Swirski, F. K., Sam, F., Nahrendorf, M. 2018; 215 (2): 423–40

    Abstract

    Macrophages populate the healthy myocardium and, depending on their phenotype, may contribute to tissue homeostasis or disease. Their origin and role in diastolic dysfunction, a hallmark of cardiac aging and heart failure with preserved ejection fraction, remain unclear. Here we show that cardiac macrophages expand in humans and mice with diastolic dysfunction, which in mice was induced by either hypertension or advanced age. A higher murine myocardial macrophage density results from monocyte recruitment and increased hematopoiesis in bone marrow and spleen. In humans, we observed a parallel constellation of hematopoietic activation: circulating myeloid cells are more frequent, and splenic 18F-FDG PET/CT imaging signal correlates with echocardiographic indices of diastolic dysfunction. While diastolic dysfunction develops, cardiac macrophages produce IL-10, activate fibroblasts, and stimulate collagen deposition, leading to impaired myocardial relaxation and increased myocardial stiffness. Deletion of IL-10 in macrophages improves diastolic function. These data imply expansion and phenotypic changes of cardiac macrophages as therapeutic targets for cardiac fibrosis leading to diastolic dysfunction.

    View details for PubMedID 29339450

    View details for PubMedCentralID PMC5789416

  • Guidelines for experimental models of myocardial ischemia and infarction. American journal of physiology. Heart and circulatory physiology Lindsey, M. L., Bolli, R., Canty, J. M., Du, X. J., Frangogiannis, N. G., Frantz, S., Gourdie, R. G., Holmes, J. W., Jones, S. P., Kloner, R. A., Lefer, D. J., Liao, R., Murphy, E., Ping, P., Przyklenk, K., Recchia, F. A., Schwartz Longacre, L., Ripplinger, C. M., Van Eyk, J. E., Heusch, G. 2018; 314 (4): H812–H838

    Abstract

    Myocardial infarction is a prevalent major cardiovascular event that arises from myocardial ischemia with or without reperfusion, and basic and translational research is needed to better understand its underlying mechanisms and consequences for cardiac structure and function. Ischemia underlies a broad range of clinical scenarios ranging from angina to hibernation to permanent occlusion, and while reperfusion is mandatory for salvage from ischemic injury, reperfusion also inflicts injury on its own. In this consensus statement, we present recommendations for animal models of myocardial ischemia and infarction. With increasing awareness of the need for rigor and reproducibility in designing and performing scientific research to ensure validation of results, the goal of this review is to provide best practice information regarding myocardial ischemia-reperfusion and infarction models. Listen to this article's corresponding podcast at ajpheart.podbean.com/e/guidelines-for-experimental-models-of-myocardial-ischemia-and-infarction/.

    View details for PubMedID 29351451

    View details for PubMedCentralID PMC5966768

  • Geographic Disparities in Reported US Amyloidosis Mortality From 1979 to 2015: Potential Underdetection of Cardiac Amyloidosis. JAMA cardiology Alexander, K. M., Orav, J., Singh, A., Jacob, S. A., Menon, A., Padera, R. F., Kijewski, M. F., Liao, R., Di Carli, M. F., Laubach, J. P., Falk, R. H., Dorbala, S. 2018

    Abstract

    Cardiac amyloidosis is an underdiagnosed disease and is highly fatal when untreated. Early diagnosis and treatment with the emerging novel therapies significantly improve survival. A comprehensive analysis of amyloidosis-related mortality is critical to appreciate the nature and distribution of underdiagnosis and improve disease detection.To evaluate the temporal and regional trends in age-adjusted amyloidosis-related mortality among men and women of various races/ethnicities in the United States.In this observational cohort study, death certificate information from the Centers for Disease Control and Prevention's Wide-ranging ONline Data for Epidemiologic Research database and the National Vital Statistics System from 1979 to 2015 was analyzed. A total of 30 764 individuals in the United States with amyloidosis listed as the underlying cause of death and 26 591 individuals with amyloidosis listed as a contributing cause of death were analyzed.Region of residence.Age-adjusted mortality rate from amyloidosis per 1 000 000 population stratified by year, sex, race/ethnicity, and state and county of residence.Of the 30 764 individuals with amyloidosis listed as the underlying cause of death, 17 421 (56.6%) were men and 27 312 (88.8%) were 55 years or older. From 1979 to 2015, the reported overall mean age-adjusted mortality rate from amyloidosis as the underlying cause of death doubled from 1.77 to 3.96 per 1 000 000 population (2.32 to 5.43 in men and 1.35 to 2.80 in women). Black men had the highest mortality rate (12.36 per 1 000 000), followed by black women (6.48 per 1 000 000). Amyloidosis contributed to age-adjusted mortality rates as high as 31.73 per 1 000 000 in certain counties. Most southern states reported the lowest US mortality rates despite having the highest proportions of black individuals.The increased reported mortality over time and in proximity to amyloidosis centers more likely reflects an overall increase in disease diagnosis rather than increased lethality. The reported amyloidosis mortality is highly variable in different US regions. The lack of higher reported mortality rates in states with a greater proportion of black residents suggests underdiagnosis of amyloidosis, including cardiac forms of the disease, in many areas of the United States. Better understanding of the determinants of geographic and racial disparity in the reporting of amyloidosis deaths are warranted.

    View details for PubMedID 30046835

  • Why publish in the American Journal of Physiology-Heart and Circulatory Physiology? American journal of physiology. Heart and circulatory physiology Zucker, I. H., Lindsey, M. L., Delmar, M., De Windt, L. J., Des Rosiers, C., Diz, D. I., Hester, R. L., Jones, S. P., Kanagy, N. L., Kitakaze, M., Liao, R., Lopaschuk, G. D., Patel, K. P., Recchia, F. A., Sadoshima, J., Shah, A. M., Ungvari, Z., Benjamin, I. J., Blaustein, M. P., Charkoudian, N., Efimov, I. R., Gutterman, D., Kass, D. A., Liao, Y., O'Leary, D. S., Ripplinger, C. M., Wolin, M. S. 2017; 313 (2): H221–H223

    View details for PubMedID 28626081

  • Developmental Regulation of Mitochondrial Apoptosis by c-Myc Governs Age- and Tissue-Specific Sensitivity to Cancer Therapeutics. Cancer cell Sarosiek, K. A., Fraser, C., Muthalagu, N., Bhola, P. D., Chang, W., McBrayer, S. K., Cantlon, A., Fisch, S., Golomb-Mello, G., Ryan, J. A., Deng, J., Jian, B., Corbett, C., Goldenberg, M., Madsen, J. R., Liao, R., Walsh, D., Sedivy, J., Murphy, D. J., Carrasco, D. R., Robinson, S., Moslehi, J., Letai, A. 2017; 31 (1): 142–56

    Abstract

    It is not understood why healthy tissues can exhibit varying levels of sensitivity to the same toxic stimuli. Using BH3 profiling, we find that mitochondria of many adult somatic tissues, including brain, heart, and kidneys, are profoundly refractory to pro-apoptotic signaling, leading to cellular resistance to cytotoxic chemotherapies and ionizing radiation. In contrast, mitochondria from these tissues in young mice and humans are primed for apoptosis, predisposing them to undergo cell death in response to genotoxic damage. While expression of the apoptotic protein machinery is nearly absent by adulthood, in young tissues its expression is driven by c-Myc, linking developmental growth to cell death. These differences may explain why pediatric cancer patients have a higher risk of developing treatment-associated toxicities.

    View details for PubMedID 28017613

    View details for PubMedCentralID PMC5363285

  • Theranostic Nucleic Acid Binding Nanoprobe Exerts Anti-inflammatory and Cytoprotective Effects in Ischemic Injury. Theranostics Chen, H. H., Yuan, H., Cho, H., Feng, Y., Ngoy, S., Kumar, A. T., Liao, R., Chao, W., Josephson, L., Sosnovik, D. E. 2017; 7 (4): 814–25

    Abstract

    Extracellular nucleic acids are proinflammatory molecules that have been implicated in a diverse range of diseases. We report here the development of a multivalent nucleic acid scavenging nanoprobe, where the fluorochrome thiazole orange (TO) is conjugated to a polymeric 40 kDa dextran carrier. Dextran-TO (Dex-TO) has nanomolar affinity for mammalian and bacterial nucleic acids and attenuates the production of inflammatory cytokines from activated macrophages exposed to DNA and RNA. Mice with myocardial ischemia reperfusion that were treated with Dex-TO showed a decrease in myocardial macrophage infiltration at 24 hours (p<0.05) and a decrease in infarct size (18% ± 9%, p<0.01) on day 7. Dex-TO allows sites of injury to be identified with fluorescence imaging, while simultaneously exerting an anti-inflammatory and cytoprotective effect. Dex-TO could be of significant diagnostic and therapeutic (theranostic) utility in a broad range of conditions including ischemia, trauma, burns, sepsis and autoimmune disease.

    View details for PubMedID 28382156

    View details for PubMedCentralID PMC5381246

  • From the BCVS Chair. Circulation research Liao, R. 2017; 120 (11): 1707–8

    View details for PubMedID 28546352

  • Amyloid Cardiomyopathy: Disease on the Rise. Circulation research Liao, R., Ward, J. E. 2017; 120 (12): 1865–67

    View details for PubMedID 28596171

    View details for PubMedCentralID PMC5584551

  • AL (Light-Chain) Cardiac Amyloidosis: A Review of Diagnosis and Therapy. Journal of the American College of Cardiology Falk, R. H., Alexander, K. M., Liao, R., Dorbala, S. 2016; 68 (12): 1323-1341

    Abstract

    The amyloidoses are a group of protein-folding disorders in which ≥1 organ is infiltrated by proteinaceous deposits known as amyloid. The deposits are derived from 1 of several amyloidogenic precursor proteins, and the prognosis of the disease is determined both by the organ(s) involved and the type of amyloid. Amyloid involvement of the heart (cardiac amyloidosis) carries the worst prognosis of any involved organ, and light-chain (AL) amyloidosis is the most serious form of the disease. The last decade has seen considerable progress in understanding the amyloidoses. In this review, current and novel approaches to the diagnosis and treatment of cardiac amyloidosis are discussed, with particular reference to AL amyloidosis in the heart.

    View details for DOI 10.1016/j.jacc.2016.06.053

    View details for PubMedID 27634125

  • Early Detection of Drug-Induced Renal Hemodynamic Dysfunction Using Sonographic Technology in Rats. Journal of visualized experiments : JoVE Fisch, S., Liao, R., Hsiao, L. L., Lu, T. 2016

    Abstract

    The kidney normally functions to maintain hemodynamic homeostasis and is a major site of damage caused by drug toxicity. Drug-induced nephrotoxicity is estimated to contribute to 19- 25% of all clinical cases of acute kidney injury (AKI) in critically ill patients. AKI detection has historically relied on metrics such as serum creatinine (sCr) or blood urea nitrogen (BUN) which are demonstrably inadequate in full assessment of nephrotoxicity in the early phase of renal dysfunction. Currently, there is no robust diagnostic method to accurately detect hemodynamic alteration in the early phase of AKI while such alterations might actually precede the rise in serum biomarker levels. Such early detection can help clinicians make an accurate diagnosis and help in in decision making for therapeutic strategy. Rats were treated with Cisplatin to induce AKI. Nephrotoxicity was assessed for six days using high-frequency sonography, sCr measurement and upon histopathology of kidney. Hemodynamic evaluation using 2D and Color-Doppler images were used to serially study nephrotoxicity in rats, using the sonography. Our data showed successful drug-induced kidney injury in adult rats by histological examination. Color-Doppler based sonographic assessment of AKI indicated that resistive-index (RI) and pulsatile-index (PI) were increased in the treatment group; and peak-systolic velocity (mm/s), end-diastolic velocity (mm/s) and velocity-time integral (VTI, mm) were decreased in renal arteries in the same group. Importantly, these hemodynamic changes evaluated by sonography preceded the rise of sCr levels. Sonography-based indices such as RI or PI can thus be useful predictive markers of declining renal function in rodents. From our sonography-based observations in the kidneys of rats that underwent AKI, we showed that these noninvasive hemodynamic measurements may consider as an accurate, sensitive and robust method in detecting early stage kidney dysfunction. This study also underscores the importance of ethical issues associated with animal use in research.

    View details for PubMedID 27022768

    View details for PubMedCentralID PMC4828235

  • Viewing Extrinsic Proteotoxic Stress Through the Lens of Amyloid Cardiomyopathy. Physiology (Bethesda, Md.) Sapp, V., Jain, M., Liao, R. 2016; 31 (4): 294–99

    Abstract

    Proteotoxicity refers to toxic stress caused by misfolded proteins of extrinsic or intrinsic origin and plays an integral role in the pathogenesis of cardiovascular diseases. Herein, we provide an overview of the current understanding of mechanisms underlying proteotoxicity and its contribution in the pathogenesis of amyloid cardiomyopathy.

    View details for PubMedID 27252164

    View details for PubMedCentralID PMC6195664

  • Fortune Favors the Prepared: Safety and Efficacy of Allogeneic Hypoxia Preconditioned Mesenchymal Stromal Cells in Primates. Circulation research Kuster, G. M., Liao, R. 2016; 118 (6): 908–10

    View details for PubMedID 26987910

    View details for PubMedCentralID PMC5198302

  • MicroRNA-34a Plays a Key Role in Cardiac Repair and Regeneration Following Myocardial Infarction. Circulation research Yang, Y., Cheng, H. W., Qiu, Y., Dupee, D., Noonan, M., Lin, Y. D., Fisch, S., Unno, K., Sereti, K. I., Liao, R. 2015; 117 (5): 450–59

    Abstract

    In response to injury, the rodent heart is capable of virtually full regeneration via cardiomyocyte proliferation early in life. This regenerative capacity, however, is diminished as early as 1 week postnatal and remains lost in adulthood. The mechanisms that dictate postinjury cardiomyocyte proliferation early in life remain unclear.To delineate the role of miR-34a, a regulator of age-associated physiology, in regulating cardiac regeneration secondary to myocardial infarction (MI) in neonatal and adult mouse hearts.Cardiac injury was induced in neonatal and adult hearts through experimental MI via coronary ligation. Adult hearts demonstrated overt cardiac structural and functional remodeling, whereas neonatal hearts maintained full regenerative capacity and cardiomyocyte proliferation and recovered to normal levels within 1-week time. As early as 1 week postnatal, miR-34a expression was found to have increased and was maintained at high levels throughout the lifespan. Intriguingly, 7 days after MI, miR-34a levels further increased in the adult but not neonatal hearts. Delivery of a miR-34a mimic to neonatal hearts prohibited both cardiomyocyte proliferation and subsequent cardiac recovery post MI. Conversely, locked nucleic acid-based anti-miR-34a treatment diminished post-MI miR-34a upregulation in adult hearts and significantly improved post-MI remodeling. In isolated cardiomyocytes, we found that miR-34a directly regulated cell cycle activity and death via modulation of its targets, including Bcl2, Cyclin D1, and Sirt1.miR-34a is a critical regulator of cardiac repair and regeneration post MI in neonatal hearts. Modulation of miR-34a may be harnessed for cardiac repair in adult myocardium.

    View details for PubMedID 26082557

    View details for PubMedCentralID PMC4769861

  • A role for matrix stiffness in the regulation of cardiac side population cell function. American journal of physiology. Heart and circulatory physiology Qiu, Y., Bayomy, A. F., Gomez, M. V., Bauer, M., Du, P., Yang, Y., Zhang, X., Liao, R. 2015; 308 (9): H990–7

    Abstract

    The mechanical properties of the local microenvironment may have important influence on the fate and function of adult tissue progenitor cells, altering the regenerative process. This is particularly critical following a myocardial infarction, in which the normal, compliant myocardial tissue is replaced with fibrotic, stiff scar tissue. In this study, we examined the effects of matrix stiffness on adult cardiac side population (CSP) progenitor cell behavior. Ovine and murine CSP cells were isolated and cultured on polydimethylsiloxane substrates, replicating the elastic moduli of normal and fibrotic myocardium. Proliferation capacity and cell cycling were increased in CSP cells cultured on the stiff substrate with an associated reduction in cardiomyogeneic differentiation and accelerated cell ageing. In addition, culture on stiff substrate stimulated upregulation of extracellular matrix and adhesion proteins gene expression in CSP cells. Collectively, we demonstrate that microenvironment properties, including matrix stiffness, play a critical role in regulating progenitor cell functions of endogenous resident CSP cells. Understanding the effects of the tissue microenvironment on resident cardiac progenitor cells is a critical step toward achieving functional cardiac regeneration.

    View details for PubMedID 25724498

    View details for PubMedCentralID PMC4551131

  • Ultrasound based assessment of coronary artery flow and coronary flow reserve using the pressure overload model in mice. Journal of visualized experiments : JoVE Chang, W. T., Fisch, S., Chen, M., Qiu, Y., Cheng, S., Liao, R. 2015: e52598

    Abstract

    Transthoracic Doppler echocardiography (TTDE) is a clinically useful, noninvasive tool for studying coronary artery flow velocity and coronary flow reserve (CFR) in humans. Reduced CFR is accompanied by marked intramyocardial and pericoronary fibrosis and is used as an indication of the severity of dysfunction. This study explores, step-by-step, the real-time changes measured in the coronary flow velocity, CFR and systolic to diastolic peak velocity (S/D) ratio in the setting of an aortic banding model in mice. By using a Doppler transthoracic imaging technique that yields reproducible and reliable data, the method assesses changes in flow in the septal coronary artery (SCA), for a period of over two weeks in mice, that previously either underwent aortic banding or thoracotomy. During imaging, hyperemia in all mice was induced by isoflurane, an anesthetic that increased coronary flow velocity when compared with resting flow. All images were acquired by a single imager. Two ratios, (1) CFR, the ratio between hyperemic and baseline flow velocities, and (2) systolic (S) to diastolic (D) flow were determined, using a proprietary software and by two independent observers. Importantly, the observed changes in coronary flow preceded LV dysfunction as evidenced by normal LV mass and fractional shortening (FS). The method was benchmarked against the current gold standard of coronary assessment, histopathology. The latter technique showed clear pathologic changes in the coronary artery in the form of peri-coronary fibrosis that correlated to the flow changes as assessed by echocardiography. The study underscores the value of using a non-invasive technique to monitor coronary circulation in mouse hearts. The method minimizes redundant use of research animals and demonstrates that advanced ultrasound-based indices, such as CFR and S/D ratios, can serve as viable diagnostic tools in a variety of investigational protocols including drug studies and the study of genetically modified strains.

    View details for PubMedID 25938185

    View details for PubMedCentralID PMC4541549

  • Lysosomal dysfunction and impaired autophagy underlie the pathogenesis of amyloidogenic light chain-mediated cardiotoxicity. EMBO molecular medicine Guan, J., Mishra, S., Qiu, Y., Shi, J., Trudeau, K., Las, G., Liesa, M., Shirihai, O. S., Connors, L. H., Seldin, D. C., Falk, R. H., MacRae, C. A., Liao, R. 2014; 6 (11): 1493–1507

    Abstract

    AL amyloidosis is the consequence of clonal production of amyloidogenic immunoglobulin light chain (LC) proteins, often resulting in a rapidly progressive and fatal amyloid cardiomyopathy. Recent work has found that amyloidogenic LC directly initiate a cardio-toxic response underlying the pathogenesis of the cardiomyopathy; however, the mechanisms that contribute to this proteotoxicity remain unknown. Using human amyloidogenic LC isolated from patients with amyloid cardiomyopathy, we reveal that dysregulation of autophagic flux is critical for mediating amyloidogenic LC proteotoxicity. Restoration of autophagic flux by pharmacological intervention using rapamycin protected against amyloidogenic light chain protein-induced pathologies including contractile dysfunction and cell death at the cellular and organ level and also prolonged survival in an in vivo zebrafish model of amyloid cardiotoxicity. Mechanistically, we identify impaired lysosomal function to be the major cause of defective autophagy and amyloidogenic LC-induced proteotoxicity. Collectively, these findings detail the downstream molecular mechanisms underlying AL amyloid cardiomyopathy and highlight potential targeting of autophagy and lysosomal dysfunction in patients with amyloid cardiomyopathy.

    View details for PubMedID 25319546

    View details for PubMedCentralID PMC4237473

  • FLT3 activation improves post-myocardial infarction remodeling involving a cytoprotective effect on cardiomyocytes. Journal of the American College of Cardiology Pfister, O., Lorenz, V., Oikonomopoulos, A., Xu, L., Häuselmann, S. P., Mbah, C., Kaufmann, B. A., Liao, R., Wodnar-Filipowicz, A., Kuster, G. M. 2014; 63 (10): 1011–19

    Abstract

    The goal of this study was to define the role of FMS-like tyrosine kinase 3 (FLT3) in the heart.FLT3 is a prominent target of receptor tyrosine kinase inhibitors (TKIs) used for anticancer therapy. TKIs can cause cardiomyopathy but understanding of the mechanisms is incomplete, partly because the roles of specific TKI target receptors in the heart are still obscure.Myocardial infarction was induced in mice by permanent ligation of the left anterior descending coronary artery followed by intramyocardial injection of FLT3 ligand (FL) or vehicle into the infarct border zone. Cardiac morphology and function were assessed by echocardiography and histological analysis 1 week after infarction. In addition, FLT3 expression and regulation, as well as molecular mechanisms of FLT3 action, were examined in cardiomyocytes in vitro.The intramyocardial injection of FL into the infarct border zone decreased infarct size and ameliorated post-myocardial infarction remodeling and function in mice. This beneficial effect was associated with reduced apoptosis, including myocytes in the infarct border zone. Cardiomyocytes expressed functional FLT3, and FLT3 messenger ribonucleic acid and protein were up-regulated under oxidative stress, identifying cardiomyocytes as FL target cells. FLT3 activation with FL protected cardiomyocytes from oxidative stress-induced apoptosis via an Akt-dependent mechanism involving Bcl-2 family protein regulation and inhibition of the mitochondrial death pathway.FLT3 is a cytoprotective system in the heart and a potential therapeutic target in ischemic cardiac injury. The protective mechanisms uncovered here may be further explored in view of potential cardiotoxic effects of FLT3-targeting anticancer therapy, particularly in patients with ischemic heart disease.

    View details for PubMedID 24184252

  • Microfluidics-assisted fabrication of gelatin-silica core-shell microgels for injectable tissue constructs. Biomacromolecules Cha, C., Oh, J., Kim, K., Qiu, Y., Joh, M., Shin, S. R., Wang, X., Camci-Unal, G., Wan, K. T., Liao, R., Khademhosseini, A. 2014; 15 (1): 283–90

    Abstract

    Microfabrication technology provides a highly versatile platform for engineering hydrogels used in biomedical applications with high-resolution control and injectability. Herein, we present a strategy of microfluidics-assisted fabrication photo-cross-linkable gelatin microgels, coupled with providing protective silica hydrogel layer on the microgel surface to ultimately generate gelatin-silica core-shell microgels for applications as in vitro cell culture platform and injectable tissue constructs. A microfluidic device having flow-focusing channel geometry was utilized to generate droplets containing methacrylated gelatin (GelMA), followed by a photo-cross-linking step to synthesize GelMA microgels. The size of the microgels could easily be controlled by varying the ratio of flow rates of aqueous and oil phases. Then, the GelMA microgels were used as in vitro cell culture platform to grow cardiac side population cells on the microgel surface. The cells readily adhered on the microgel surface and proliferated over time while maintaining high viability (∼90%). The cells on the microgels were also able to migrate to their surrounding area. In addition, the microgels eventually degraded over time. These results demonstrate that cell-seeded GelMA microgels have a great potential as injectable tissue constructs. Furthermore, we demonstrated that coating the cells on GelMA microgels with biocompatible and biodegradable silica hydrogels via sol-gel method provided significant protection against oxidative stress which is often encountered during and after injection into host tissues, and detrimental to the cells. Overall, the microfluidic approach to generate cell-adhesive microgel core, coupled with silica hydrogels as a protective shell, will be highly useful as a cell culture platform to generate a wide range of injectable tissue constructs.

    View details for PubMedID 24344625

    View details for PubMedCentralID PMC3922064

  • Regenerative therapy for cardiovascular disease. Translational research : the journal of laboratory and clinical medicine Pfister, O., Della Verde, G., Liao, R., Kuster, G. M. 2014; 163 (4): 307–20

    Abstract

    Recent insights into myocardial biology uncovered a hereto unknown regenerative capacity of the adult heart. The discovery of dividing cardiomyocytes and the identification and characterization of cardiac stem and progenitor cells with myogenic and angiogenic potential have generated new hopes that cardiac regeneration and repair might become a therapeutic option. During the past decade, multiple candidate cells have been proposed for cardiac regeneration, and their mechanisms of action in the myocardium have been explored. Initial clinical trials have focused on the use of bone marrow-derived cells to promote myocardial regeneration in ischemic heart disease and have yielded very mixed results, with no clear signs of clinically meaningful functional improvement. Although the efficiency of bona fide cardiomyocyte generation is generally low, stem cells delivered into the myocardium act mainly via paracrine mechanisms. More recent studies taking advantage of cardiac committed cells (eg, resident cardiac progenitor cells or primed cardiogenic mesenchymal stem cells) showed promising results in first clinical pilot trials. Also, transplantation of cardiomyogenic cells generated by induced pluripotent stem cells and genetic reprogramming of dividing nonmyocytes into cardiomyocytes may constitute attractive new regenerative approaches in cardiovascular medicine in the future. We discuss advantages and limitations of specific cell types proposed for cell-based therapy in cardiology and give an overview of the first clinical trials using this novel therapeutic approach in patients with cardiovascular disease.

    View details for PubMedID 24378637

  • Assessment of right ventricular structure and function in mouse model of pulmonary artery constriction by transthoracic echocardiography. Journal of visualized experiments : JoVE Cheng, H. W., Fisch, S., Cheng, S., Bauer, M., Ngoy, S., Qiu, Y., Guan, J., Mishra, S., Mbah, C., Liao, R. 2014: e51041

    Abstract

    Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure(1-3). Moreover, the RV is significantly affected in pulmonary diseases such as pulmonary artery hypertension (PAH). In addition, the RV is remarkably sensitive to cardiac pathologies, including left ventricular (LV) dysfunction, valvular disease or RV infarction(4). To understand the role of RV in the pathogenesis of cardiac diseases, a reliable and noninvasive method to access the RV structurally and functionally is essential. A noninvasive trans-thoracic echocardiography (TTE) based methodology was established and validated for monitoring dynamic changes in RV structure and function in adult mice. To impose RV stress, we employed a surgical model of pulmonary artery constriction (PAC) and measured the RV response over a 7-day period using a high-frequency ultrasound microimaging system. Sham operated mice were used as controls. Images were acquired in lightly anesthetized mice at baseline (before surgery), day 0 (immediately post-surgery), day 3, and day 7 (post-surgery). Data was analyzed offline using software. Several acoustic windows (B, M, and Color Doppler modes), which can be consistently obtained in mice, allowed for reliable and reproducible measurement of RV structure (including RV wall thickness, end-diastolic and end-systolic dimensions), and function (fractional area change, fractional shortening, PA peak velocity, and peak pressure gradient) in normal mice and following PAC. Using this method, the pressure-gradient resulting from PAC was accurately measured in real-time using Color Doppler mode and was comparable to direct pressure measurements performed with a Millar high-fidelity microtip catheter. Taken together, these data demonstrate that RV measurements obtained from various complimentary views using echocardiography are reliable, reproducible and can provide insights regarding RV structure and function. This method will enable a better understanding of the role of RV cardiac dysfunction.

    View details for PubMedID 24513696

    View details for PubMedCentralID PMC4397999

  • Cardiac stem cells: biology and clinical applications. Antioxidants & redox signaling Goichberg, P., Chang, J., Liao, R., Leri, A. 2014; 21 (14): 2002–17

    Abstract

    Heart disease is the primary cause of death in the industrialized world. Cardiac failure is dictated by an uncompensated reduction in the number of viable and fully functional cardiomyocytes. While current pharmacological therapies alleviate the symptoms associated with cardiac deterioration, heart transplantation remains the only therapy for advanced heart failure. Therefore, there is a pressing need for novel therapeutic modalities. Cell-based therapies involving cardiac stem cells (CSCs) constitute a promising emerging approach for the replenishment of the lost tissue and the restoration of cardiac contractility.CSCs reside in the adult heart and govern myocardial homeostasis and repair after injury by producing new cardiomyocytes and vascular structures. In the last decade, different classes of immature cells expressing distinct stem cell markers have been identified and characterized in terms of their growth properties, differentiation potential, and regenerative ability. Phase I clinical trials, employing autologous CSCs in patients with ischemic cardiomyopathy, are being completed with encouraging results.Accumulating evidence concerning the role of CSCs in heart regeneration imposes a reconsideration of the mechanisms of cardiac aging and the etiology of heart failure. Deciphering the molecular pathways that prevent activation of CSCs in their environment and understanding the processes that affect CSC survival and regenerative function with cardiac pathologies, commonly accompanied by alterations in redox conditions, are of great clinical importance.Further investigations of CSC biology may be translated into highly effective and novel therapeutic strategies aiming at the enhancement of the endogenous healing capacity of the diseased heart.

    View details for PubMedID 24597850

    View details for PubMedCentralID PMC4208604

  • Ly-6Chigh monocytes depend on Nr4a1 to balance both inflammatory and reparative phases in the infarcted myocardium. Circulation research Hilgendorf, I., Gerhardt, L. M., Tan, T. C., Winter, C., Holderried, T. A., Chousterman, B. G., Iwamoto, Y., Liao, R., Zirlik, A., Scherer-Crosbie, M., Hedrick, C. C., Libby, P., Nahrendorf, M., Weissleder, R., Swirski, F. K. 2014; 114 (10): 1611–22

    Abstract

    Healing after myocardial infarction involves the biphasic accumulation of inflammatory lymphocyte antigen 6C (Ly-6C)(high) and reparative Ly-6C(low) monocytes/macrophages (Mo/MΦ). According to 1 model, Mo/MΦ heterogeneity in the heart originates in the blood and involves the sequential recruitment of distinct monocyte subsets that differentiate to distinct macrophages. Alternatively, heterogeneity may arise in tissue from 1 circulating subset via local macrophage differentiation and polarization. The orphan nuclear hormone receptor, nuclear receptor subfamily 4, group a, member 1 (Nr4a1), is essential to Ly-6C(low) monocyte production but dispensable to Ly-6C(low) macrophage differentiation; dependence on Nr4a1 can thus discriminate between systemic and local origins of macrophage heterogeneity.This study tested the role of Nr4a1 in myocardial infarction in the context of the 2 Mo/MΦ accumulation scenarios.We show that Ly-6C(high) monocytes infiltrate the infarcted myocardium and, unlike Ly-6C(low) monocytes, differentiate to cardiac macrophages. In the early, inflammatory phase of acute myocardial ischemic injury, Ly-6C(high) monocytes accrue in response to a brief C-C chemokine ligand 2 burst. In the second, reparative phase, accumulated Ly-6C(high) monocytes give rise to reparative Ly-6C(low) F4/80(high) macrophages that proliferate locally. In the absence of Nr4a1, Ly-6C(high) monocytes express heightened levels of C-C chemokine receptor 2 on their surface, avidly infiltrate the myocardium, and differentiate to abnormally inflammatory macrophages, which results in defective healing and compromised heart function.Ly-6C(high) monocytes orchestrate both inflammatory and reparative phases during myocardial infarction and depend on Nr4a1 to limit their influx and inflammatory cytokine expression.

    View details for PubMedID 24625784

    View details for PubMedCentralID PMC4017349

  • Identifying early changes in myocardial microstructure in hypertensive heart disease. PloS one Hiremath, P., Bauer, M., Aguirre, A. D., Cheng, H. W., Unno, K., Patel, R. B., Harvey, B. W., Chang, W. T., Groarke, J. D., Liao, R., Cheng, S. 2014; 9 (5): e97424

    Abstract

    The transition from healthy myocardium to hypertensive heart disease is characterized by a series of poorly understood changes in myocardial tissue microstructure. Incremental alterations in the orientation and integrity of myocardial fibers can be assessed using advanced ultrasonic image analysis. We used a modified algorithm to investigate left ventricular myocardial microstructure based on analysis of the reflection intensity at the myocardial-pericardial interface on B-mode echocardiographic images. We evaluated the extent to which the novel algorithm can differentiate between normal myocardium and hypertensive heart disease in humans as well as in a mouse model of afterload resistance. The algorithm significantly differentiated between individuals with uncomplicated essential hypertension (N = 30) and healthy controls (N = 28), even after adjusting for age and sex (P = 0.025). There was a trend in higher relative wall thickness in hypertensive individuals compared to controls (P = 0.08), but no difference between groups in left ventricular mass (P = 0.98) or total wall thickness (P = 0.37). In mice, algorithm measurements (P = 0.026) compared with left ventricular mass (P = 0.053) more clearly differentiated between animal groups that underwent fixed aortic banding, temporary aortic banding, or sham procedure, on echocardiography at 7 weeks after surgery. Based on sonographic signal intensity analysis, a novel imaging algorithm provides an accessible, non-invasive measure that appears to differentiate normal left ventricular microstructure from myocardium exposed to chronic afterload stress. The algorithm may represent a particularly sensitive measure of the myocardial changes that occur early in the course of disease progression.

    View details for PubMedID 24831515

    View details for PubMedCentralID PMC4022613

  • Worming along in amyloid cardiotoxicity. Blood Liao, R. 2014; 123 (23): 3525–26

    View details for PubMedID 24904094

    View details for PubMedCentralID PMC4047492

  • MicroRNA-26a regulates pathological and physiological angiogenesis by targeting BMP/SMAD1 signaling. Circulation research Icli, B., Wara, A. K., Moslehi, J., Sun, X., Plovie, E., Cahill, M., Marchini, J. F., Schissler, A., Padera, R. F., Shi, J., Cheng, H. W., Raghuram, S., Arany, Z., Liao, R., Croce, K., MacRae, C., Feinberg, M. W. 2013; 113 (11): 1231–41

    Abstract

    The rapid induction and orchestration of new blood vessels are critical for tissue repair in response to injury, such as myocardial infarction, and for physiological angiogenic responses, such as embryonic development and exercise.We aimed to identify and characterize microRNAs (miR) that regulate pathological and physiological angiogenesis.We show that miR-26a regulates pathological and physiological angiogenesis by targeting endothelial cell (EC) bone morphogenic protein/SMAD1 signaling in vitro and in vivo. MiR-26a expression is increased in a model of acute myocardial infarction in mice and in human subjects with acute coronary syndromes. Ectopic expression of miR-26a markedly induced EC cycle arrest and inhibited EC migration, sprouting angiogenesis, and network tube formation in matrigel, whereas blockade of miR-26a had the opposite effects. Mechanistic studies demonstrate that miR-26a inhibits the bone morphogenic protein/SMAD1 signaling pathway in ECs by binding to the SMAD1 3'-untranslated region, an effect that decreased expression of Id1 and increased p21(WAF/CIP) and p27. In zebrafish, miR-26a overexpression inhibited formation of the caudal vein plexus, a bone morphogenic protein-responsive process, an effect rescued by ectopic SMAD1 expression. In mice, miR-26a overexpression inhibited EC SMAD1 expression and exercise-induced angiogenesis. Furthermore, systemic intravenous administration of an miR-26a inhibitor, locked nucleic acid-anti-miR-26a, increased SMAD1 expression and rapidly induced robust angiogenesis within 2 days, an effect associated with reduced myocardial infarct size and improved heart function.These findings establish miR-26a as a regulator of bone morphogenic protein/SMAD1-mediated EC angiogenic responses, and that manipulating miR-26a expression could provide a new target for rapid angiogenic therapy in ischemic disease states.

    View details for PubMedID 24047927

    View details for PubMedCentralID PMC4068743

  • Optimized ventricular restraint therapy: adjustable restraint is superior to standard restraint in an ovine model of ischemic cardiomyopathy. The Journal of thoracic and cardiovascular surgery Lee, L. S., Ghanta, R. K., Mokashi, S. A., Coelho-Filho, O., Kwong, R. Y., Kwon, M., Guan, J., Liao, R., Chen, F. Y. 2013; 145 (3): 824–31

    Abstract

    The effects of ventricular restraint level on left ventricular reverse remodeling are not known. We hypothesized that restraint level affects the degree of reverse remodeling and that restraint applied in an adjustable manner is superior to standard, nonadjustable restraint.This study was performed in 2 parts using a model of chronic heart failure in the sheep. In part I, restraint was applied at control (0 mm Hg, n = 3), low (1.5 mm Hg, n = 3), and high (3.0 mm Hg, n = 3) levels with an adjustable and measurable ventricular restraint (AMVR) device. Restraint level was not altered throughout the 2-month treatment period. Serial restraint level measurements and transthoracic echocardiography were performed. In part II, restraint was applied with the AMVR device set at 3.0 mm Hg (n = 6) and adjusted periodically to maintain that level. This was compared with restraint applied in a standard, nonadjustable manner using a mesh wrap (n = 6). All subjects were followed up for 2 months with serial magnetic resonance imaging.In part I, there was greater and earlier reverse remodeling in the high restraint group. In both groups, the rate of reverse remodeling peaked and then declined as the measured restraint level decreased with progression of reverse remodeling. In part II, adjustable restraint resulted in greater reverse remodeling than standard restraint. Left ventricular end diastolic volume decreased by 12.7% (P = .005) with adjustable restraint and by 5.7% (P = .032) with standard restraint. Left ventricular ejection fraction increased by 18.9% (P = .014) and 14.4% (P < .001) with adjustable and standard restraint, respectively.Restraint level affects the rate and degree of reverse remodeling and is an important determinant of therapy efficacy. Adjustable restraint is more effective than nonadjustable restraint in promoting reverse remodeling.

    View details for PubMedID 22698557

    View details for PubMedCentralID PMC3954527

  • ATP-binding cassette G-subfamily transporter 2 regulates cell cycle progression and asymmetric division in mouse cardiac side population progenitor cells. Circulation research Sereti, K. I., Oikonomopoulos, A., Unno, K., Cao, X., Qiu, Y., Liao, R. 2013; 112 (1): 27–34

    Abstract

    After cardiac injury, cardiac progenitor cells are acutely reduced and are replenished in part by regulated self-renewal and proliferation, which occurs through symmetric and asymmetric cellular division. Understanding the molecular cues controlling progenitor cell self-renewal and lineage commitment is critical for harnessing these cells for therapeutic regeneration. We previously have found that the cell surface ATP-binding cassette G-subfamily transporter 2 (Abcg2) influences the proliferation of cardiac side population (CSP) progenitor cells, but through unclear mechanisms.To determine the role of Abcg2 on cell cycle progression and mode of division in mouse CSP cells.Herein, using CSP cells isolated from wild-type and Abcg2 knockout mice, we found that Abcg2 regulates G1-S cell cycle transition by fluorescence ubiquitination cell cycle indicators, cell cycle-focused gene expression arrays, and confocal live-cell fluorescent microscopy. Moreover, we found that modulation of cell cycle results in transition from symmetric to asymmetric cellular division in CSP cells lacking Abcg2.Abcg2 modulates CSP cell cycle progression and asymmetric cell division, establishing a mechanistic link between this surface transporter and cardiac progenitor cell function. Greater understanding of progenitor cell biology and, in particular, the regulation of resident progenitor cell homeostasis is vital for guiding the future development of cell-based therapies for cardiac regeneration.

    View details for PubMedID 23136123

    View details for PubMedCentralID PMC3959170

  • PGC1α plays a critical role in TWEAK-induced cardiac dysfunction. PloS one Shi, J., Jiang, B., Qiu, Y., Guan, J., Jain, M., Cao, X., Bauer, M., Su, L., Burkly, L. C., Leone, T. C., Kelly, D. P., Liao, R. 2013; 8 (1): e54054

    Abstract

    Inflammatory cytokines play an important role in the pathogenesis of heart failure. We have recently found the cytokine TWEAK (tumor necrosis factor (TNF)-like weak inducer of apoptosis), a member of the TNF superfamily, to be increased in patients with cardiomyopathy and result in the development of heart failure when overexpressed in mice. The molecular mechanisms underlying TWEAK-induced cardiac pathology, however, remain unknown.Using mouse models of elevated circulating TWEAK levels, established through intravenous injection of adenovirus expressing TWEAK or recombinant TWEAK protein, we find that TWEAK induces a progressive dilated cardiomyopathy with impaired contractile function in mice. Moreover, TWEAK treatment is associated with decreased expression of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1α) and genes required for mitochondrial oxidative phosphorylation, which precede the onset of cardiac dysfunction. TWEAK-induced downregulation of PGC1α requires expression of its cell surface receptor, fibroblast growth factor-inducible 14 (Fn14). We further find that TWEAK downregulates PGC1α gene expression via the TNF receptor-associated factor 2 (TRAF2) and NFκB signaling pathways. Maintaining PGC1α levels through adenoviral-mediated gene expression is sufficient to protect against TWEAK-induced cardiomyocyte dysfunction.Collectively, our data suggest that TWEAK induces cardiac dysfunction via downregulation of PGC1α, through FN14-TRAF2-NFκB-dependent signaling. Selective targeting of the FN14-TRAF2-NFκB-dependent signaling pathway or augmenting PGC1α levels may serve as novel therapeutic strategies for cardiomyopathy and heart failure.

    View details for PubMedID 23342071

    View details for PubMedCentralID PMC3546975

  • Regional cardiac dysfunction and dyssynchrony in a murine model of afterload stress. PloS one Bauer, M., Cheng, S., Unno, K., Lin, F. C., Liao, R. 2013; 8 (4): e59915

    Abstract

    Small animal models of afterload stress have contributed much to our present understanding of the progression from hypertension to heart failure. High-sensitivity methods for phenotyping cardiac function in vivo, particular in the setting of compensated cardiac hypertrophy, may add new information regarding alterations in cardiac performance that can occur even during the earliest stages of exposure to pressure overload. We have developed an echocardiographic analytical method, based on speckle-tracking-based strain analyses, and used this tool to rapidly phenotype cardiac changes resulting from afterload stress in a small animal model. Adult mice were subjected to ascending aortic constriction, with and without subsequent reversal of the pressure gradient. In this model of compensated hypertrophic cardiac remodeling, conventional echocardiographic measurements did not detect changes in left ventricular (LV) function at the early time points examined. Strain analyses, however, revealed a decrement in basal longitudinal myofiber shortening that was induced by aortic constriction and improved following relief of the pressure gradient. Furthermore, we observed that pressure overload resulted in LV segmental dyssynchrony that was attenuated with return of the afterload to baseline levels. Herein, we describe the use of echocardiographic strain analyses for cardiac phenotyping in a mouse model of pressure overload. This method provides evidence of dyssynchrony and regional myocardial dysfunction that occurs early with compensatory hypertrophy, and improves following relief of aortic constriction. Importantly, these findings illustrate the utility of a rapid, non-invasive method for characterizing early cardiac dysfunction, not detectable by conventional echocardiography, following afterload stress.

    View details for PubMedID 23560059

    View details for PubMedCentralID PMC3613376

  • Human amyloidogenic light chain proteins result in cardiac dysfunction, cell death, and early mortality in zebrafish. American journal of physiology. Heart and circulatory physiology Mishra, S., Guan, J., Plovie, E., Seldin, D. C., Connors, L. H., Merlini, G., Falk, R. H., MacRae, C. A., Liao, R. 2013; 305 (1): H95–103

    Abstract

    Systemic amyloid light-chain (AL) amyloidosis is associated with rapidly progressive and fatal cardiomyopathy resulting from the direct cardiotoxic effects of circulating AL light chain (AL-LC) proteins and the indirect effects of AL fibril tissue infiltration. Cardiac amyloidosis is resistant to standard heart failure therapies, and, to date, there are limited treatment options for these patients. The mechanisms underlying the development of cardiac amyloidosis and AL-LC cardiotoxicity are largely unknown, and their study has been limited by the lack of a suitable in vivo model system. Here, we establish an in vivo zebrafish model of human AL-LC-induced cardiotoxicity. AL-LC isolated from AL cardiomyopathy patients or control nonamyloidogenic LC protein isolated from multiple myeloma patients (Con-LC) was directly injected into the circulation of zebrafish at 48 h postfertilization. AL-LC injection resulted in impaired cardiac function, pericardial edema, and increased cell death relative to Con-LC, culminating in compromised survival with 100% mortality within 2 wk, independent of AL fibril deposition. Prior work has implicated noncanonical p38 MAPK activation in the pathogenesis of AL-LC-induced cardiotoxicity, and p38 MAPK inhibition via SB-203580 rescued AL-LC-induced cardiac dysfunction and cell death and attenuated mortality in zebrafish. This in vivo zebrafish model of AL-LC cardiotoxicity demonstrates that antagonism of p38 MAPK within the AL-LC cardiotoxic signaling response may serve to improve cardiac function and mortality in AL cardiomyopathy. Furthermore, this in vivo model system will allow for further study of the molecular underpinnings of AL cardiotoxicity and identification of novel therapeutic strategies.

    View details for PubMedID 23624626

    View details for PubMedCentralID PMC3727100

  • Methods to study the proliferation and differentiation of cardiac side population (CSP) cells. Methods in molecular biology (Clifton, N.J.) Sereti, K. I., Oikonomopoulos, A., Unno, K., Liao, R. 2013; 1036: 95–106

    Abstract

    Investigation of cardiac progenitor cell proliferation and differentiation is essential for both the basic understanding of progenitor cell biology as well as the development of cellular therapeutics for tissue regeneration. Herein, we describe techniques used for the analysis of CSP cell proliferation, cell cycle status, and cardiomyogenic differentiation.

    View details for PubMedID 23807790

  • Stanniocalcin1 is a key mediator of amyloidogenic light chain induced cardiotoxicity. Basic research in cardiology Guan, J., Mishra, S., Shi, J., Plovie, E., Qiu, Y., Cao, X., Gianni, D., Jiang, B., Del Monte, F., Connors, L. H., Seldin, D. C., Lavatelli, F., Rognoni, P., Palladini, G., Merlini, G., Falk, R. H., Semigran, M. J., Dec, G. W., Macrae, C. A., Liao, R. 2013; 108 (5): 378

    Abstract

    Immunoglobulin light chain (LC) amyloidosis (AL) results from overproduction of circulating amyloidogenic LC proteins and subsequent amyloid fibril deposition in organs. Mortality in AL amyloidosis patients is highly associated with a rapidly progressive AL cardiomyopathy, marked by profound impairment of diastolic and systolic cardiac function and significant early mortality. While myocardial fibril deposition contributes to the severe diastolic dysfunction seen in AL cardiomyopathy patients, the degree of fibril deposition has not been found to correlate with prognosis. Previously, we and others showed a direct cardiotoxic effect of amyloidogenic LC proteins (AL-LC), which may contribute to the pathophysiology and mortality observed in AL cardiomyopathy patients. However, the mechanisms underlying AL-LC related cardiotoxicity remain unknown. Mammalian stanniocalcin1 (STC1) is associated with a number of cellular processes including oxidative stress and cell death. Herein, we find that STC1 expression is elevated in cardiac tissue from AL cardiomyopathy patients, and is induced in isolated cardiomyocytes in response to AL-LC, but not non-amyloidogenic LC. STC1 overexpression in vitro recapitulates the pathophysiology of AL-LC mediated cardiotoxicity, with increased ROS production, contractile dysfunction and cell death. Overexpression of STC1 in vivo results in significant cardiac dysfunction and cell death. Genetic silencing of STC1 prevents AL-LC induced cardiotoxicity in cardiomyocytes and protects against AL-LC induced cell death and early mortality in zebrafish. The cardiotoxic effects of STC1 appears to be mediated via mitochondrial dysfunction as indicated by loss of mitochondrial membrane potential, ROS production and increased mitochondrial calcium levels. Collectively, this work identifies STC1 as a critical determinant of AL-LC cardiotoxicity.

    View details for PubMedID 23982491

    View details for PubMedCentralID PMC3914405

  • Adult cardiac progenitor cell aggregates exhibit survival benefit both in vitro and in vivo. PloS one Bauer, M., Kang, L., Qiu, Y., Wu, J., Peng, M., Chen, H. H., Camci-Unal, G., Bayomy, A. F., Sosnovik, D. E., Khademhosseini, A., Liao, R. 2012; 7 (11): e50491

    Abstract

    A major hurdle in the use of exogenous stems cells for therapeutic regeneration of injured myocardium remains the poor survival of implanted cells. To date, the delivery of stem cells into myocardium has largely focused on implantation of cell suspensions.We hypothesize that delivering progenitor cells in an aggregate form would serve to mimic the endogenous state with proper cell-cell contact, and may aid the survival of implanted cells. Microwell methodologies allow for the culture of homogenous 3D cell aggregates, thereby allowing cell-cell contact. In this study, we find that the culture of cardiac progenitor cells in a 3D cell aggregate augments cell survival and protects against cellular toxins and stressors, including hydrogen peroxide and anoxia/reoxygenation induced cell death. Moreover, using a murine model of cardiac ischemia-reperfusion injury, we find that delivery of cardiac progenitor cells in the form of 3D aggregates improved in vivo survival of implanted cells.Collectively, our data support the notion that growth in 3D cellular systems and maintenance of cell-cell contact improves exogenous cell survival following delivery into myocardium. These approaches may serve as a strategy to improve cardiovascular cell-based therapies.

    View details for PubMedID 23226295

    View details for PubMedCentralID PMC3511575

  • Homocysteine induces cardiomyocyte dysfunction and apoptosis through p38 MAPK-mediated increase in oxidant stress. Journal of molecular and cellular cardiology Wang, X., Cui, L., Joseph, J., Jiang, B., Pimental, D., Handy, D. E., Liao, R., Loscalzo, J. 2012; 52 (3): 753–60

    Abstract

    Elevated plasma homocysteine (Hcy) is a risk factor for cardiovascular disease. While Hcy has been shown to promote endothelial dysfunction by decreasing the bioavailability of nitric oxide and increasing oxidative stress in the vasculature, the effects of Hcy on cardiomyocytes remain less understood. In this study we explored the effects of hyperhomocysteinemia (HHcy) on myocardial function ex vivo and examined the direct effects of Hcy on cardiomyocyte function and survival in vitro. Studies with isolated hearts from wild type and HHcy mice (heterozygous cystathionine-beta synthase deficient mice) demonstrated that HHcy mouse hearts had more severely impaired cardiac relaxation and contractile function and increased cell death following ischemia reperfusion (I/R). In isolated cultured adult rat ventricular myocytes, exposure to Hcy for 24 h impaired cardiomyocyte contractility in a concentration-dependent manner, and promoted apoptosis as revealed by terminal dUTP nick-end labeling and cleaved caspase-3 immunoblotting. These effects were associated with activation of p38 MAPK, decreased expression of thioredoxin (TRX) protein, and increased production of reactive oxygen species (ROS). Inhibition of p38 MAPK by the selective inhibitor SB203580 (5 μM) prevented all of these Hcy-induced changes. Furthermore, adenovirus-mediated overexpression of TRX in cardiomyocytes significantly attenuated Hcy-induced ROS generation, apoptosis, and impairment of myocyte contractility. Thus, Hcy may increase the risk for CVD not only by causing endothelial dysfunction, but also by directly exerting detrimental effects on cardiomyocytes.

    View details for PubMedID 22227328

    View details for PubMedCentralID PMC3294144

  • Cardiac side population cells: moving toward the center stage in cardiac regeneration. Circulation research Unno, K., Jain, M., Liao, R. 2012; 110 (10): 1355–63

    Abstract

    Over the past decade, extensive work in animal models and humans has identified the presence of adult cardiac progenitor cells, capable of cardiomyogenic differentiation and likely contributors to cardiomyocyte turnover during normal development and disease. Among cardiac progenitor cells, there is a distinct subpopulation, termed "side population" (SP) progenitor cells, identified by their unique ability to efflux DNA binding dyes through an ATP-binding cassette transporter. This review highlights the literature on the isolation, characterization, and functional relevance of cardiac SP cells. We review the initial discovery of cardiac SP cells in adult myocardium as well as their capacity for functional cardiomyogenic differentiation and role in cardiac regeneration after myocardial injury. Finally, we discuss recent advances in understanding the molecular regulators of cardiac SP cell proliferation and differentiation, as well as likely future areas of investigation required to realize the goal of effective cardiac regeneration.

    View details for PubMedID 22581921

    View details for PubMedCentralID PMC3412159

  • The continuing evolution of the Langendorff and ejecting murine heart: new advances in cardiac phenotyping. American journal of physiology. Heart and circulatory physiology Liao, R., Podesser, B. K., Lim, C. C. 2012; 303 (2): H156–67

    Abstract

    The isolated retrograde-perfused Langendorff heart and the isolated ejecting heart have, over many decades, resulted in fundamental discoveries that form the underpinnings of our current understanding of the biology and physiology of the heart. These two experimental methodologies have proven invaluable in studying pharmacological effects on myocardial function, metabolism, and vascular reactivity and in the investigation of clinically relevant disease states such as ischemia-reperfusion injury, diabetes, obesity, and heart failure. With the advent of the genomics era, the isolated mouse heart preparation has gained prominence as an ex vivo research tool for investigators studying the impact of gene modification in the intact heart. This review summarizes the historical development of the isolated heart and provides a practical guide for the establishment of the Langendorff and ejecting heart preparations with a particular emphasis on the murine heart. In addition, current applications and novel methods of recording cardiovascular parameters in the isolated heart preparation will be discussed. With continued advances in methodological recordings, the isolated mouse heart preparation will remain physiologically relevant for the foreseeable future, serving as an integral bridge between in vitro assays and in vivo approaches.

    View details for PubMedID 22636675

    View details for PubMedCentralID PMC3404701

  • Spot identification and quality control in cell-based microarrays. ACS combinatorial science Bauer, M., Kim, K., Qiu, Y., Calpe, B., Khademhosseini, A., Liao, R., Wheeldon, I. 2012; 14 (8): 471–77

    Abstract

    Cell-based microarrays are being increasingly used as a tool for combinatorial and high throughput screening of cellular microenvironments. Analysis of microarrays requires several steps, including microarray imaging, identification of cell spots, quality control, and data exploration. While high content image analysis, cell counting, and cell pattern recognition methods are established, there is a need for new postprocessing and quality control methods for cell-based microarrays used to investigate combinatorial microenvironments. Previously, microarrayed cell spot identification and quality control were performed manually, leading to excessive processing time and potentially resulting in human bias. This work introduces an automated approach to identify cell-based microarray spots and spot quality control. The approach was used to analyze the adhesion of murine cardiac side population cells on combinatorial arrays of extracellular matrix proteins. Microarrays were imaged by automated fluorescence microscopy and cells were identified using open-source image analysis software (CellProfiler). From these images, clusters of cells making up single cell spots were reliably identified by analyzing the distances between cells using a density-based clustering algorithm (OPTICS). Naïve Bayesian classifiers trained on manually scored training sets identified good and poor quality spots using spot size, number of cells per spot, and cell location as quality control criteria. Combined, the approach identified 78% of high quality spots and 87% of poor quality spots. Full factorial analysis of the resulting microarray data revealed that collagen IV exhibited the highest positive effect on cell attachment. This data processing approach allows for fast and unbiased analysis of cell-based microarray data.

    View details for PubMedID 22850537

    View details for PubMedCentralID PMC3495599

  • Regeneration in heart disease-Is ECM the key? Life sciences Bayomy, A. F., Bauer, M., Qiu, Y., Liao, R. 2012; 91 (17-18): 823–27

    Abstract

    The heart possesses a regeneration potential derived from endogenous and exogenous stem and progenitor cell populations, though baseline regeneration appears to be sub-therapeutic. This limitation was initially attributed to a lack of cells with cardiomyogenic potential following an insult to the myocardium. Rather, recent studies demonstrate increased numbers of cardiomyocyte progenitor cells in diseased hearts. Given that the limiting factor does not appear to be cell quantity but rather repletion of functional cardiomyocytes, it is crucial to understand potential mechanisms inhibiting progenitor cell differentiation. One of the extensively studied areas in heart disease is extracellular matrix (ECM) remodeling, with both the composition and mechanical properties of the ECM undergoing changes in diseased hearts. This review explores the influence of ECM properties on cardiomyogenesis and adult cardiac progenitor cells.

    View details for PubMedID 22982346

    View details for PubMedCentralID PMC4013147

  • Notch1 in Bone Marrow-Derived Cells Mediates Cardiac Repair After Myocardial Infarction CIRCULATION Li, Y., Hiroi, Y., Ngoy, S., Okamoto, R., Noma, K., Wang, C., Wang, H., Zhou, Q., Radtke, F., Liao, R., Liao, J. K. 2011; 123 (8): 866-U83

    Abstract

    The signaling mechanisms that regulate the recruitment of bone marrow (BM)-derived cells to the injured heart are not well known. Notch receptors mediate binary cell fate determination and may regulate the function of BM-derived cells. However, it is not known whether Notch1 signaling in BM-derived cells mediates cardiac repair after myocardial injury.Mice with postnatal cardiac-specific deletion of Notch1 exhibit infarct size and heart function after ischemic injury that is similar to that of control mice. However, mice with global hemizygous deletion of Notch1 (N1(±)) developed larger infarct size and worsening heart function. When the BM of N1(±) mice were transplanted into wild-type (WT) mice, infarct size and heart function were worsened and neovascularization in the infarct border area was reduced compared with WT mice transplanted with WT BM. In contrast, transplantation of WT BM into N1(±) mice lessened the myocardial injury observed in N1(±) mice. Indeed, hemizygous deletion of Notch1 in BM-derived cells leads to decreased recruitment, proliferation, and survival of mesenchymal stem cells (MSC). Compared with WT MSC, injection of N1(±) MSC into the infarcted heart leads to increased myocardial injury whereas injection of MSC overexpressing Notch intracellular domain leads to decreased infarct size and improved cardiac function.These findings indicate that Notch1 signaling in BM-derived cells is critical for cardiac repair and suggest that strategies that increase Notch1 signaling in BM-derived MSC could have therapeutic benefits in patients with ischemic heart disease.

    View details for DOI 10.1161/CIRCULATIONAHA.110.947531

    View details for Web of Science ID 000287801300013

    View details for PubMedID 21321153

    View details for PubMedCentralID PMC3488350

  • Wnt signaling exerts an antiproliferative effect on adult cardiac progenitor cells through IGFBP3. Circulation research Oikonomopoulos, A., Sereti, K. I., Conyers, F., Bauer, M., Liao, A., Guan, J., Crapps, D., Han, J. K., Dong, H., Bayomy, A. F., Fine, G. C., Westerman, K., Biechele, T. L., Moon, R. T., Force, T., Liao, R. 2011; 109 (12): 1363–74

    Abstract

    Recent work in animal models and humans has demonstrated the presence of organ-specific progenitor cells required for the regenerative capacity of the adult heart. In response to tissue injury, progenitor cells differentiate into specialized cells, while their numbers are maintained through mechanisms of self-renewal. The molecular cues that dictate the self-renewal of adult progenitor cells in the heart, however, remain unclear.We investigate the role of canonical Wnt signaling on adult cardiac side population (CSP) cells under physiological and disease conditions.CSP cells isolated from C57BL/6J mice were used to study the effects of canonical Wnt signaling on their proliferative capacity. The proliferative capacity of CSP cells was also tested after injection of recombinant Wnt3a protein (r-Wnt3a) in the left ventricular free wall. Wnt signaling was found to decrease the proliferation of adult CSP cells, both in vitro and in vivo, through suppression of cell cycle progression. Wnt stimulation exerted its antiproliferative effects through a previously unappreciated activation of insulin-like growth factor binding protein 3 (IGFBP3), which requires intact IGF binding site for its action. Moreover, injection of r-Wnt3a after myocardial infarction in mice showed that Wnt signaling limits CSP cell renewal, blocks endogenous cardiac regeneration and impairs cardiac performance, highlighting the importance of progenitor cells in maintaining tissue function after injury.Our study identifies canonical Wnt signaling and the novel downstream mediator, IGFBP3, as key regulators of adult cardiac progenitor self-renewal in physiological and pathological states.

    View details for PubMedID 22034491

    View details for PubMedCentralID PMC3384997

  • Echocardiographic speckle-tracking based strain imaging for rapid cardiovascular phenotyping in mice. Circulation research Bauer, M., Cheng, S., Jain, M., Ngoy, S., Theodoropoulos, C., Trujillo, A., Lin, F. C., Liao, R. 2011; 108 (8): 908–16

    Abstract

    High-sensitivity in vivo phenotyping of cardiac function is essential for evaluating genes of interest and novel therapies in small animal models of cardiovascular disease. Transthoracic echocardiography is the principal method currently used for assessing cardiac structure and function; however, standard echocardiographic techniques are relatively insensitive to early or subtle changes in cardiac performance, particularly in mice.To develop and validate an echocardiographic strain imaging methodology for sensitive and rapid cardiac phenotyping in small animal models.Herein, we describe a modified echocardiographic technique that uses speckle-tracking based strain analysis for the noninvasive evaluation of cardiac performance in adult mice. This method is found to be rapid, reproducible, and highly sensitive in assessing both regional and global left ventricular (LV) function. Compared with conventional echocardiographic measures of LV structure and function, peak longitudinal strain and strain rate were able to detect changes in adult mouse hearts at an earlier time point following myocardial infarction and predicted the later development of adverse LV remodeling. Moreover, speckle-tracking based strain analysis was able to clearly identify subtle improvement in LV function that occurred early in response to standard post-myocardial infarction cardiac therapy.Our results highlight the utility of speckle-tracking based strain imaging for detecting discrete functional alterations in mouse models of cardiovascular disease in an efficient and comprehensive manner. Echocardiography speckle-tracking based strain analysis represents a method for relatively high-throughput and sensitive cardiac phenotyping, particularly in evaluating emerging cardiac agents and therapies in mice.

    View details for PubMedID 21372284

    View details for PubMedCentralID PMC3376717

  • Evidence for human lung stem cells. The New England journal of medicine Kajstura, J., Rota, M., Hall, S. R., Hosoda, T., D'Amario, D., Sanada, F., Zheng, H., Ogórek, B., Rondon-Clavo, C., Ferreira-Martins, J., Matsuda, A., Arranto, C., Goichberg, P., Giordano, G., Haley, K. J., Bardelli, S., Rayatzadeh, H., Liu, X., Quaini, F., Liao, R., Leri, A., Perrella, M. A., Loscalzo, J., Anversa, P. 2011; 364 (19): 1795–1806

    Abstract

    Although progenitor cells have been described in distinct anatomical regions of the lung, description of resident stem cells has remained elusive.Surgical lung-tissue specimens were studied in situ to identify and characterize human lung stem cells. We defined their phenotype and functional properties in vitro and in vivo.Human lungs contain undifferentiated human lung stem cells nested in niches in the distal airways. These cells are self-renewing, clonogenic, and multipotent in vitro. After injection into damaged mouse lung in vivo, human lung stem cells form human bronchioles, alveoli, and pulmonary vessels integrated structurally and functionally with the damaged organ. The formation of a chimeric lung was confirmed by detection of human transcripts for epithelial and vascular genes. In addition, the self-renewal and long-term proliferation of human lung stem cells was shown in serial-transplantation assays.Human lungs contain identifiable stem cells. In animal models, these cells participate in tissue homeostasis and regeneration. They have the undemonstrated potential to promote tissue restoration in patients with lung disease. (Funded by the National Institutes of Health.).

    View details for PubMedID 21561345

    View details for PubMedCentralID PMC3197695

  • Preventing cardiac remodeling: the combination of cell-based therapy and cardiac support therapy preserves left ventricular function in rodent model of myocardial ischemia. The Journal of thoracic and cardiovascular surgery Mokashi, S. A., Guan, J., Wang, D., Tchantchaleishvili, V., Brigham, M., Lipsitz, S., Lee, L. S., Schmitto, J. D., Bolman, R. M., Khademhosseini, A., Liao, R., Chen, F. Y. 2010; 140 (6): 1374–80

    Abstract

    Cellular and mechanical treatment to prevent heart failure each holds therapeutic promise but together have not been reported yet. The goal of the present study was to determine whether combining a cardiac support device with cell-based therapy could prevent adverse left ventricular remodeling, more than either therapy alone.The present study was completed in 2 parts. In the first part, mesenchymal stem cells were isolated from rodent femurs and seeded on a collagen-based scaffold. In the second part, myocardial infarction was induced in 60 rats. The 24 survivors were randomly assigned to 1 of 4 groups: control, stem cell therapy, cardiac support device, and a combination of stem cell therapy and cardiac support device. Left ventricular function was measured with biweekly echocardiography, followed by end-of-life histopathologic analysis at 6 weeks.After myocardial infarction and treatment intervention, the ejection fraction remained preserved (74.9-80.2%) in the combination group at an early point (2 weeks) compared with the control group (66.2-82.8%). By 6 weeks, the combination therapy group had a significantly greater fractional area of change compared with the control group (69.2% ± 6.7% and 49.5% ± 6.1% respectively, P = .03). Also, at 6 weeks, the left ventricular wall thickness was greater in the combination group than in the stem cell therapy alone group (1.79 ± 0.11 and 1.33 ± 0.13, respectively, P = .02).Combining a cardiac support device with stem cell therapy preserves left ventricular function after myocardial infarction, more than either therapy alone. Furthermore, stem cell delivery using a cardiac support device is a novel delivery approach for cell-based therapies.

    View details for PubMedID 21078426

  • Loss of hypoxia-inducible factor prolyl hydroxylase activity in cardiomyocytes phenocopies ischemic cardiomyopathy. Circulation Moslehi, J., Minamishima, Y. A., Shi, J., Neuberg, D., Charytan, D. M., Padera, R. F., Signoretti, S., Liao, R., Kaelin, W. G. 2010; 122 (10): 1004–16

    Abstract

    Ischemic cardiomyopathy is the major cause of heart failure and a significant cause of morbidity and mortality. The degree of left ventricular dysfunction in this setting is often out of proportion to the amount of overtly infarcted tissue, and how decreased delivery of oxygen and nutrients leads to impaired contractility remains incompletely understood. The Prolyl Hydroxylase Domain-Containing Protein (PHD) prolyl hydroxylases are oxygen-sensitive enzymes that transduce changes in oxygen availability into changes in the stability of the hypoxia-inducible factor transcription factor, a master regulator of genes that promote survival in a low-oxygen environment.We found that cardiac-specific PHD inactivation causes ultrastructural, histological, and functional changes reminiscent of ischemic cardiomyopathy over time. Moreover, long-term expression of a stabilized hypoxia-inducible factor alpha variant in cardiomyocytes also led to dilated cardiomyopathy.Sustained loss of PHD activity and subsequent hypoxia-inducible factor activation, as would occur in the setting of chronic ischemia, are sufficient to account for many of the changes in the hearts of individuals with chronic coronary artery disease.

    View details for PubMedID 20733101

    View details for PubMedCentralID PMC2971656

  • The paradoxical role of inflammation in cardiac repair and regeneration. Journal of cardiovascular translational research Jiang, B., Liao, R. 2010; 3 (4): 410–16

    Abstract

    Inflammation has emerged as a critical biological process contributing to nearly all aspects of cardiovascular diseases including heart failure. Heart failure represents the final consequence of a diverse set of initial insults to the myocardium, among which myocardial infarction (MI) is the most common cause. After MI, the lack of perfusion often leads to the death of cardiomyocytes. The necrotic cells trigger a cascade of inflammatory pathways that work to clear the dead cells and matrix debris, as well as to repair and heal damaged tissues. For the heart, an organ with limited regeneration capacity, the consequence of MI (termed post-MI remodeling) comprises a series of structural and functional changes, including scar formation at the infarct zone, reactive hypertrophy of the remaining cardiomyocytes at the noninfarct area, ventricular chamber dilatation, and molecular changes marked by fetal gene up-regulation, all of which have been linked to the activation of the inflammatory pathways. Inadequate or excessive inflammatory response may lead to improper cellular repair, tissue damage, and dysfunction. Herein, we summarize the current understanding of the role of inflammation in cardiac injury and repair and put forth the hypothesis that temporally regulated activation and suppression of inflammation may be critical for achieving effective cardiac repair and regeneration.

    View details for PubMedID 20559773

  • Inhibition of notch1-dependent cardiomyogenesis leads to a dilated myopathy in the neonatal heart. Circulation research Urbanek, K., Cabral-da-Silva, M. C., Ide-Iwata, N., Maestroni, S., Delucchi, F., Zheng, H., Ferreira-Martins, J., Ogórek, B., D'Amario, D., Bauer, M., Zerbini, G., Rota, M., Hosoda, T., Liao, R., Anversa, P., Kajstura, J., Leri, A. 2010; 107 (3): 429–41

    Abstract

    Physiological hypertrophy in the developing heart has been considered the product of an increase in volume of preexisting fetal cardiomyocytes in the absence of myocyte formation.In this study, we tested whether the mouse heart at birth has a pool of cardiac stem cells (CSCs) that differentiate into myocytes contributing to the postnatal expansion of the parenchymal cell compartment.We have found that the newborn heart contains a population of c-kit-positive CSCs that are lineage negative, self-renewing, and multipotent. CSCs express the Notch1 receptor and show the nuclear localization of its active fragment, N1ICD. In 60% of cases, N1ICD was coupled with the presence of Nkx2.5, indicating that the commitment of CSCs to the myocyte lineage is regulated by Notch1. Importantly, overexpression of N1ICD in neonatal CSCs significantly expanded the proportion of transit-amplifying myocytes. To establish whether these in vitro findings had a functional counterpart in vivo, the Notch pathway was blocked in newborn mice by administration of a gamma-secretase inhibitor. This intervention resulted in the development of a dilated myopathy and high mortality rates. Ventricular decompensation was characterized by a 62% reduction in amplifying myocytes, which resulted in a 54% decrease in myocyte number. After cessation of Notch blockade and recovery of myocyte regeneration, cardiac anatomy and function were largely restored.Notch1 signaling is a critical determinant of CSC growth and differentiation; when this cascade of events is altered, cardiomyogenesis is impaired, physiological cardiac hypertrophy is prevented, and a life-threatening myopathy supervenes.

    View details for PubMedID 20558824

    View details for PubMedCentralID PMC2919068

  • Amyloidogenic light chains induce cardiomyocyte contractile dysfunction and apoptosis via a non-canonical p38alpha MAPK pathway. Proceedings of the National Academy of Sciences of the United States of America Shi, J., Guan, J., Jiang, B., Brenner, D. A., Del Monte, F., Ward, J. E., Connors, L. H., Sawyer, D. B., Semigran, M. J., Macgillivray, T. E., Seldin, D. C., Falk, R., Liao, R. 2010; 107 (9): 4188–93

    Abstract

    Patients with primary (AL) cardiac amyloidosis suffer from progressive cardiomyopathy with a median survival of less than 8 months and a 5-year survival of <10%. Contributing to this poor prognosis is the fact that these patients generally do not tolerate standard heart failure therapies. The molecular mechanisms underlying this deadly form of heart disease remain unclear. Although interstitial amyloid fibril deposition of Ig light chain proteins is a major cause of cardiac dysfunction in AL cardiac amyloidosis, we have previously shown that amyloid precursor proteins directly impair cardiac function at the cellular and isolated organ levels, independent of fibril formation. In this study, we report that amyloidogenic light chain (AL-LC) proteins provoke oxidative stress, cellular dysfunction, and apoptosis in isolated adult cardiomyocytes through activation of p38 mitogen-activated protein kinase (MAPK). AL-LC-induced p38 activation was found to be independent of the upstream MAPK kinase, MKK3/6, and instead depends upon transforming growth factor-beta-activated protein kinase-1 binding protein-1 (TAB1)-mediated p38alpha MAPK autophosphorylation. Treatment of cardiomyocytes with SB203580, a selective p38 MAPK inhibitor, significantly attenuated AL-LC-induced oxidative stress, cellular dysfunction, and apoptosis. Our data provide a unique mechanistic insight into the pathogenesis of AL-LC cardiac toxicity and suggest that TAB1-mediated p38alpha MAPK autophosphorylation may serve as an important event leading to cardiac dysfunction and subsequent heart failure.

    View details for PubMedID 20150510

    View details for PubMedCentralID PMC2840082

  • Regulation of VASP phosphorylation in cardiac myocytes: differential regulation by cyclic nucleotides and modulation of protein expression in diabetic and hypertrophic heart. American journal of physiology. Heart and circulatory physiology Sartoretto, J. L., Jin, B. Y., Bauer, M., Gertler, F. B., Liao, R., Michel, T. 2009; 297 (5): H1697–710

    Abstract

    Vasodilator-stimulated phosphoprotein (VASP) is a major substrate for cyclic nucleotide-dependent kinases that has been implicated in cardiac pathology, yet many aspects of VASP's molecular regulation in cardiomyocytes are incompletely understood. In these studies, we explored the role of VASP, both in signaling pathways in isolated murine myocytes, as well as in a model of cardiac hypertrophy in VASP(null) mice. We found that the beta-adrenergic agonist isoproterenol promotes the rapid and reversible phosphorylation of VASP at Ser157 and Ser239. Forskolin and the cAMP analog 8-(4-chlorophenylthio)-cAMP promote a similar pattern of VASP phosphorylation at both sites. The effects of isoproterenol are blocked by atenolol and by compound H-89, an inhibitor of the cAMP-dependent protein kinase. By contrast, phosphorylation of VASP only at Ser239 is seen following activation of particulate guanylate cyclase by atrial natriuretic peptide, or following activation of soluble guanylate cyclase by sodium nitroprusside, or following treatment of myocytes with cGMP analog. We found that basal and isoproterenol-induced VASP phosphorylation is entirely unchanged in cardiomyocytes isolated from either endothelial or neuronal nitric oxide synthase knockout mice. In cardiomyocytes isolated from diabetic mice, only basal VASP phosphorylation is increased, whereas, in cells isolated from mice subjected to ascending aortic constriction (AAC), we found a significant increase in basal VASP expression, along with an increase in VASP phosphorylation, compared with cardiac myocytes isolated from sham-operated mice. Moreover, there is further increase in VASP phosphorylation in cells isolated from hypertrophic hearts following isoproterenol treatment. Finally, we found that VASP(null) mice subjected to transverse aortic constriction develop cardiac hypertrophy with a pattern similar to VASP(+/+) mice. Our findings establish differential receptor-modulated regulation of VASP phosphorylation in cardiomyocytes by cyclic nucleotides. Furthermore, these studies demonstrate for the first time that VASP expression is upregulated in hypertrophied heart.

    View details for PubMedID 19734360

    View details for PubMedCentralID PMC2781375

  • A feedback loop involving the Phd3 prolyl hydroxylase tunes the mammalian hypoxic response in vivo. Molecular and cellular biology Minamishima, Y. A., Moslehi, J., Padera, R. F., Bronson, R. T., Liao, R., Kaelin, W. G. 2009; 29 (21): 5729–41

    Abstract

    Hypoxia-inducible factor (HIF), consisting of a labile alpha subunit and a stable beta subunit, is a master regulator of hypoxia-responsive mRNAs. HIF alpha undergoes oxygen-dependent prolyl hydroxylation, which marks it for polyubiquitination by a complex containing the von Hippel-Lindau protein (pVHL). Among the three Phd family members, Phd2 appears to be the primary HIF prolyl hydroxylase. Phd3 is induced by HIF and, based on findings from in vitro studies, may participate in a HIF-regulatory feedback loop. Here, we report that Phd3 loss exacerbates the HIF activation, hepatic steatosis, dilated cardiomyopathy, and premature mortality observed in mice lacking Phd2 alone and produces a closer phenocopy of the changes seen in mice lacking pVHL than the loss of Phd2 alone. Importantly, the degree to which Phd3 can compensate for Phd2 loss and the degree to which the combined loss of Phd2 and Phd3 resembles pVHL loss appear to differ for different HIF-responsive genes and in different tissues. These findings highlight that the responses of different HIF target genes to changes in prolyl hydroxylase activity differ, quantitatively and qualitatively, in vivo and have implications for the development of paralog-specific prolyl hydroxylase inhibitors as therapeutic agents.

    View details for PubMedID 19720742

    View details for PubMedCentralID PMC2772748

  • Increased glucose uptake and oxidation in mouse hearts prevent high fatty acid oxidation but cause cardiac dysfunction in diet-induced obesity. Circulation Yan, J., Young, M. E., Cui, L., Lopaschuk, G. D., Liao, R., Tian, R. 2009; 119 (21): 2818–28

    Abstract

    Shift of myocardial substrate preference has been observed in many chronic diseases such as diabetes and heart failure. This study was undertaken to elucidate the mechanisms underlying the chronic substrate switch in adult hearts and to determine the functional consequences of the switch.Transgenic mice with cardiac-specific overexpression of the insulin-independent glucose transporter GLUT1 (TG) were used to increase intracellular glucose in cardiac myocytes. A high-fat diet was used to increase the fatty acid supply to the heart. High-fat diet induced a 40% increase in fatty acid oxidation in wild-type hearts, whereas glucose oxidation was decreased to 30% of the control. In contrast, glucose oxidation was >2-fold higher in TG hearts, and the high-fat diet failed to upregulate fatty acid oxidation in these hearts. Glucose induced changes in the expression of multiple metabolic genes, including peroxisome proliferator-activated receptor-alpha (decreased by 51%), 3-oxoacid CoA transferase (decreased by 67%), and acetyl-CoA carboxylase (increased by 4-fold), resulting in a remodeling of the metabolic network to favor a shift of substrate preference toward glucose. Although TG mice on a normal diet maintained normal cardiac energetics and function, the inability to upregulate myocardial fatty acid oxidation in TG mice fed a high-fat diet resulted in increased oxidative stress in the heart, activation of p38 mitogen-activated protein kinase, and contractile dysfunction.We have demonstrated that chronic increases in myocardial glucose uptake and oxidation reduce the metabolic flexibility and render the heart susceptible to contractile dysfunction.

    View details for PubMedID 19451348

    View details for PubMedCentralID PMC2765220

  • A novel role for tumor necrosis factor-like weak inducer of apoptosis (TWEAK) in the development of cardiac dysfunction and failure. Circulation Jain, M., Jakubowski, A., Cui, L., Shi, J., Su, L., Bauer, M., Guan, J., Lim, C. C., Naito, Y., Thompson, J. S., Sam, F., Ambrose, C., Parr, M., Crowell, T., Lincecum, J. M., Wang, M. Z., Hsu, Y. M., Zheng, T. S., Michaelson, J. S., Liao, R., Burkly, L. C. 2009; 119 (15): 2058–68

    Abstract

    Tumor necrosis factor-like weak inducer of apoptosis (TWEAK), a member of the tumor necrosis factor superfamily, is a multifunctional cytokine known to regulate cellular functions in contexts of injury and disease through its receptor, fibroblast growth factor-inducible molecule 14 (Fn14). Although many of the processes and downstream signals regulated by the TWEAK/Fn14 pathway have been implicated in the development of cardiac dysfunction, the role of TWEAK in the cardiovascular system is completely unknown.Herein, we demonstrate that mouse and human cardiomyocytes express the TWEAK receptor Fn14. Furthermore, we determine that elevated circulating levels of TWEAK, induced via transgenic or adenoviral-mediated gene expression in mice, result in dilated cardiomyopathy with subsequent severe cardiac dysfunction. This phenotype was mediated exclusively by the Fn14 receptor, independent of tumor necrosis factor-alpha, and was associated with cardiomyocyte elongation and cardiac fibrosis but not cardiomyocyte apoptosis. Moreover, we find that circulating TWEAK levels were differentially upregulated in patients with idiopathic dilated cardiomyopathy compared with other forms of heart disease and normal control subjects.Our data suggest that TWEAK/Fn14 may be important in regulating myocardial structural remodeling and function and may play a role in the pathogenesis of dilated cardiomyopathy.

    View details for PubMedID 19349318

    View details for PubMedCentralID PMC2924152

  • Disruption of striated preferentially expressed gene locus leads to dilated cardiomyopathy in mice. Circulation Liu, X., Ramjiganesh, T., Chen, Y. H., Chung, S. W., Hall, S. R., Schissel, S. L., Padera, R. F., Liao, R., Ackerman, K. G., Kajstura, J., Leri, A., Anversa, P., Yet, S. F., Layne, M. D., Perrella, M. A. 2009; 119 (2): 261–68

    Abstract

    The striated preferentially expressed gene (Speg) generates 4 different isoforms through alternative promoter use and tissue-specific splicing. Depending on the cell type, Speg isoforms may serve as markers of striated or smooth muscle differentiation.To elucidate function of Speg gene isoforms, we disrupted the Speg gene locus in mice by replacing common exons 8, 9, and 10 with a lacZ gene. beta-Galactosidase activity was detected in cardiomyocytes of the developing heart starting at day 11.5 days post coitum (dpc). beta-Galactosidase activity in other cell types, including vascular smooth muscle cells, did not begin until 18.5 dpc. In the developing heart, protein expression of only Spegalpha and Spegbeta isoforms was present in cardiomyocytes. Homozygous Speg mutant hearts began to enlarge by 16.5 dpc, and by 18.5 dpc, they demonstrated dilation of right and left atria and ventricles. These cardiac abnormalities in the absence of Speg were associated with a cellular hypertrophic response, myofibril degeneration, and a marked decrease in cardiac function. Moreover, Speg mutant mice exhibited significant neonatal mortality, with increased death occurring by 2 days after birth.These findings demonstrate that mutation of the Speg locus leads to cardiac dysfunction and a phenotype consistent with a dilated cardiomyopathy.

    View details for PubMedID 19118250

    View details for PubMedCentralID PMC2630246

  • Role of the ATP-binding cassette transporter Abcg2 in the phenotype and function of cardiac side population cells. Circulation research Pfister, O., Oikonomopoulos, A., Sereti, K. I., Sohn, R. L., Cullen, D., Fine, G. C., Mouquet, F., Westerman, K., Liao, R. 2008; 103 (8): 825–35

    Abstract

    Recently, the side population (SP) phenotype has been introduced as a reliable marker to identify subpopulations of cells with stem/progenitor cell properties in various tissues. We and others have identified SP cells from postmitotic tissues, including adult myocardium, in which they have been suggested to contribute to cellular regeneration following injury. SP cells are identified and characterized by a unique efflux of Hoechst 33342 dye. Abcg2 belongs to the ATP-binding cassette (ABC) transporter superfamily and constitutes the molecular basis for the dye efflux, hence the SP phenotype, in hematopoietic stem cells. Although Abcg2 is also expressed in cardiac SP (cSP) cells, its role in regulating the SP phenotype and function of cSP cells is unknown. Herein, we demonstrate that regulation of the SP phenotype in cSP cells occurs in a dynamic, age-dependent fashion, with Abcg2 as the molecular determinant of the cSP phenotype in the neonatal heart and another ABC transporter, Mdr1, as the main contributor to the SP phenotype in the adult heart. Using loss- and gain-of-function experiments, we find that Abcg2 tightly regulates cell fate and function. Adult cSP cells isolated from mice with genetic ablation of Abcg2 exhibit blunted proliferation capacity and augmented cell death. Conversely, overexpression of Abcg2 is sufficient to enhance cell proliferation, although with a limitation of cardiomyogenic differentiation. In summary, for the first time, we reveal a functional role for Abcg2 in modulating the proliferation, differentiation, and survival of adult cSP cells that goes beyond its distinct role in Hoechst dye efflux.

    View details for PubMedID 18787193

    View details for PubMedCentralID PMC3115759

  • Evolving cell-based therapies for heart failure patients. Current treatment options in cardiovascular medicine Podesser, B. K., Bauer, M., Liao, R. 2008; 10 (4): 358–67

    Abstract

    Heart failure (HF) represents the only cardiovascular disease (CVD) whose incidence continues to rise in the developed world. With recent advances in device and drug therapies, the prognosis is improving. Nevertheless, the mortality associated with HF remains high, with more than 50% of patients dying within 5 years after initial diagnosis. The loss of cardiac cells is a major contributor to the development and progression of HF, thus therapeutic interventions to repair or regenerate lost cardiac cells hold tremendous promise. During the past several years, cell-based therapy for CVD has moved at a rapid pace from animal studies to clinical trials. To date, populations enrolled in cell-based therapy trials have comprised patients with coronary artery disease and myocardial infarction, with a limited number of trials conducted in patients with congestive HF. Also, most trials have used autologous skeletal myoblasts or bone marrow cells (whole bone marrow or subpopulations). The outcomes from these studies have been largely mixed, ranging from clear beneficial effects of cell therapy to no observed improvement, although all trials demonstrated a reasonable degree of safety, at least within the study period. Several critical issues, such as the type of cells, number of cells, timing, delivery methods, and the mechanisms of action involved, remain to be elucidated. This article reviews the current status of the emerging field of cell-based therapies for CVD, with particular focus on HF treatment.

    View details for PubMedID 18647591

  • Isolation, culture, and functional analysis of adult mouse cardiomyocytes. Methods in molecular medicine Liao, R., Jain, M. 2007; 139: 251–62

    Abstract

    The pathogenesis of heart disease and the development of myocardial failure are highly dependent upon the cardiomyocyte-the basic contractile cell within the heart. Understanding and elucidating the complex networks that regulate cardiomyocyte function are central to the development of specific target-based therapeutic interventions. The relative recent advances in molecular genetics and generation and routine usage of transgenic and knockout mouse models have further necessitated that previously established cardiomyocyte methods be adapted for the isolation, culture, and study of primary adult murine cardiomyocytes, both freshly isolated and in culture. Such adaptation is based not only upon scalability of established techniques, as the mouse heart is an order of magnitude smaller than the rat heart, but also upon properties unique to the mouse. This chapter therefore describes current methods for the isolation, culture, and functional analysis of adult murine cardiomyocytes.

    View details for PubMedID 18287677

  • Long-term effects of increased glucose entry on mouse hearts during normal aging and ischemic stress. Circulation Luptak, I., Yan, J., Cui, L., Jain, M., Liao, R., Tian, R. 2007; 116 (8): 901–9

    Abstract

    A shift of substrate preference toward glucose in the heart is considered a reversion to fetal metabolic profile, but its role in the pathogenesis of cardiac diseases is incompletely understood.We performed a 2-year follow-up study in transgenic mice with sustained high glucose uptake and utilization in the heart by cardiac-specific overexpression of the insulin-independent glucose transporter GLUT1 (GLUT1-TG). Compared with wild-type litter mates, the GLUT1-TG mice showed a normal survival rate and unaltered contractile function of the heart monitored by serial echocardiography and by pressure-volume studies in isolated perfused hearts in the 2-year period. Furthermore, when hearts were subjected to ischemia-reperfusion, cardiac function of young and old GLUT1-TG recovered to the same level (86% and 83%, respectively) and exceeded that of both young and old wild-type hearts (52% and 35%, respectively; P<0.05). Nuclear magnetic resonance spectroscopic measurements with 31P showed delayed ATP depletion, reduced acidosis during ischemia, and improved recovery of high-energy phosphate content in old GLUT1-TG hearts (P<0.05 versus old wild-type). During reperfusion, glucose oxidation was 3-fold higher and fatty acid oxidation was 45% lower in old GLUT1-TG hearts compared with old wild-type (P<0.05), which suggests that the deleterious effects of excessive fatty acid oxidation during reperfusion was prevented in old GLUT1-TG hearts.We have demonstrated that a normal heart is able to adapt to long-term increases in basal glucose entry into cardiomyocytes without development of glucotoxicity. Furthermore, life-long increases in glucose uptake result in a favorable metabolic phenotype that affords protections against aging-associated increase of susceptibility to ischemic injury.

    View details for PubMedID 17679614

  • Adult stem cells and heart regeneration. Expert review of cardiovascular therapy Sohn, R. L., Jain, M., Liao, R. 2007; 5 (3): 507–17

    Abstract

    Cardiovascular disease remains the single greatest cause of death in the Western world, claiming more lives in the USA than the next four leading causes combined. Among these diseases, the incidence of heart failure continues to rise at a staggering rate. Recent advances in medical and device therapies have dramatically improved both the survival and quality of life of many of these patients; however, limited strategies are available to address the central pathophysiology underlying the development of heart failure, namely, the loss of functional cardiomyocytes. Therefore, one recent strategy has been the development of cell-based therapies, aiming towards the replacement of injured or lost cardiomyocytes and thereby improved cardiac function. In this review, we will examine the cell types undergoing investigation as potential cell-based therapies and provide an overview of current clinical trials utilizing cell-based therapeutic approaches in patients with heart disease.

    View details for PubMedID 17489674

  • Transcription factor CHF1/Hey2 suppresses cardiac hypertrophy through an inhibitory interaction with GATA4. American journal of physiology. Heart and circulatory physiology Xiang, F., Sakata, Y., Cui, L., Youngblood, J. M., Nakagami, H., Liao, J. K., Liao, R., Chin, M. T. 2006; 290 (5): H1997–2006

    Abstract

    Pathological cardiac hypertrophy is considered a precursor to clinical heart failure. Understanding the transcriptional regulators that suppress the hypertrophic response may have profound implications for the treatment of heart disease. We report the generation of transgenic mice that overexpress the transcription factor CHF1/Hey2 in the myocardium. In response to the alpha-adrenergic agonist phenylephrine, they show marked attenuation in the hypertrophic response compared with wild-type controls, even though blood pressure is similar in both groups. Isolated myocytes from transgenic mice demonstrate a similar resistance to phenylephrine-induced hypertrophy in vitro, providing further evidence that the protective effect of CHF1/Hey2 is mediated at the myocyte level. Induction of the hypertrophy marker genes ANF, BNP, and beta-MHC in the transgenic cells is concurrently suppressed in vivo and in vitro, demonstrating that the induction of hypertrophy-associated genes is repressed by CHF1/Hey2. Transfection of CHF1/Hey2 into neonatal cardiomyocytes suppresses activation of an ANF reporter plasmid by the transcription factor GATA4, which has previously been shown to activate a hypertrophic transcriptional program. Furthermore, CHF1/Hey2 binds GATA4 directly in coimmunoprecipitation assays and inhibits the binding of GATA4 to its recognition sequence within the ANF promoter. Our findings demonstrate that CHF1/Hey2 functions as an antihypertrophic gene, possibly through inhibition of a GATA4-dependent hypertrophic program.

    View details for PubMedID 16603706

    View details for PubMedCentralID PMC2692281

  • Selective loss of fine tuning of Gq/11 signaling by RGS2 protein exacerbates cardiomyocyte hypertrophy. The Journal of biological chemistry Zhang, W., Anger, T., Su, J., Hao, J., Xu, X., Zhu, M., Gach, A., Cui, L., Liao, R., Mende, U. 2006; 281 (9): 5811–20

    Abstract

    Alterations in cardiac G protein-mediated signaling, most prominently G(q/11) signaling, are centrally involved in hypertrophy and heart failure development. Several RGS proteins that can act as negative regulators of G protein signaling are expressed in the heart, but their functional roles are still poorly understood. RGS expression changes have been described in hypertrophic and failing hearts. In this study, we report a marked decrease in RGS2 (but not other major cardiac RGS proteins (RGS3-RGS5)) that occurs prior to hypertrophy development in different models with enhanced G(q/11) signaling (transgenic expression of activated Galpha(q)(*) and pressure overload due to aortic constriction). To assess functional consequences of selective down-regulation of endogenous RGS2, we identified targeting sequences for effective RGS2 RNA interference and used lipid-based transfection to achieve uptake of fluorescently labeled RGS2 small interfering RNA in >90% of neonatal and adult ventricular myocytes. Endogenous RGS2 expression was dose-dependently suppressed (up to 90%) with no major change in RGS3-RGS5. RGS2 knockdown increased phenylephrine- and endothelin-1-induced phospholipase Cbeta stimulation in both cell types and exacerbated the hypertrophic effect (increase in cell size and radiolabeled protein) in neonatal myocytes, with no major change in G(q/11)-mediated ERK1/2, p38, or JNK activation. Taken together, this study demonstrates that endogenous RGS2 exerts functionally important inhibitory restraint on G(q/11)-mediated phospholipase Cbeta activation and hypertrophy in ventricular myocytes. Our findings point toward a potential pathophysiological role of loss of fine tuning due to selective RGS2 down-regulation in G(q/11)-mediated remodeling. Furthermore, this study shows the feasibility of effective RNA interference in cardiomyocytes using lipid-based small interfering RNA transfection.

    View details for PubMedID 16380388

  • Restoration of cardiac progenitor cells after myocardial infarction by self-proliferation and selective homing of bone marrow-derived stem cells. Circulation research Mouquet, F., Pfister, O., Jain, M., Oikonomopoulos, A., Ngoy, S., Summer, R., Fine, A., Liao, R. 2005; 97 (11): 1090–92

    Abstract

    Tissue-specific progenitor cells contribute to local cellular regeneration and maintain organ function. Recently, we have determined that cardiac side-population (CSP) cells represent a distinct cardiac progenitor cell population, capable of in vitro differentiation into functional cardiomyocytes. The response of endogenous CSP to myocardial injury, however, and the cellular mechanisms that maintain this cardiac progenitor cell pool in vivo remain unknown. In this report we demonstrate that local progenitor cell proliferation maintains CSP under physiologic conditions, with little contribution from extracardiac stem cell sources. Following myocardial infarction in adult mice, however, CSP cells are acutely depleted, both within the infarct and noninfarct areas. CSP pools are subsequently reconstituted to baseline levels within 7 days after myocardial infarction, through both proliferation of resident CSP cells, as well as through homing of bone marrow-derived stem cells (BMC) to specific areas of myocardial injury and immunophenotypic conversion of BMC to adopt a CSP phenotype. We, therefore, conclude that following myocardial injury, cardiac progenitor cell populations are acutely depleted and are reconstituted to normal levels by both self-proliferation and selective homing of BMC. Understanding and enhancing such processes hold enormous potential for therapeutic myocardial regeneration.

    View details for PubMedID 16269652

  • Mesenchymal stem cells in the infarcted heart. Coronary artery disease Jain, M., Pfister, O., Hajjar, R. J., Liao, R. 2005; 16 (2): 93–97

    Abstract

    A loss of functional cardiomyocytes forms the cellular basis of cardiac dysfunction and heart failure. Stem cell based repletion of scarred myocardial tissue and regeneration of cardiomyocytes have been proposed as a potential treatment of ventricular dysfunction. In this review, we provide an overview of recent studies utilizing mesenchymal stem cells in cardiac regeneration and post-myocardial infarct therapy.

    View details for PubMedID 15735401

  • Cardiac-specific overexpression of GLUT1 prevents the development of heart failure attributable to pressure overload in mice. Circulation Liao, R., Jain, M., Cui, L., D'Agostino, J., Aiello, F., Luptak, I., Ngoy, S., Mortensen, R. M., Tian, R. 2002; 106 (16): 2125–31

    Abstract

    Increased rates of glucose uptake and glycolysis have been repeatedly observed in cardiac hypertrophy and failure. Although these changes have been considered part of the fetal gene reactivation program, the functional significance of increased glucose utilization in hypertrophied and failing myocardium is poorly understood.We generated transgenic (TG) mice with cardiac-specific overexpression of insulin-independent glucose transporter GLUT1 to recapitulate the increases in basal glucose uptake rate observed in hypertrophied hearts. Isolated perfused TG hearts showed a greater rate of basal glucose uptake and glycolysis than hearts isolated from wild-type littermates, which persisted after pressure overload by ascending aortic constriction (AAC). The in vivo cardiac function in TG mice, assessed by echocardiography, was unaltered. When subjected to AAC, wild-type mice exhibited a progressive decline in left ventricular (LV) fractional shortening accompanied by ventricular dilation and decreased phosphocreatine to ATP ratio and reached a mortality rate of 40% at 8 weeks. In contrast, TG-AAC mice maintained LV function and phosphocreatine to ATP ratio and had <10% mortality.We found that increasing insulin-independent glucose uptake and glycolysis in adult hearts does not compromise cardiac function. Furthermore, we demonstrate that increasing glucose utilization in hypertrophied hearts protects against contractile dysfunction and LV dilation after chronic pressure overload.

    View details for PubMedID 12379584