Professional Education


  • Bachelor of Science, Wuhan University (2011)
  • Doctor of Philosophy, Chinese Academy Of Sciences (2017)

Stanford Advisors


All Publications


  • Single cell expression analysis reveals anatomical and cell cycle-dependent transcriptional shifts during heart development. Development (Cambridge, England) Li, G., Tian, L., Goodyer, W., Kort, E. J., Buikema, J. W., Xu, A., Wu, J., Jovinge, S., Wu, S. M. 2019

    Abstract

    The heart is a complex organ composed of multiple cell and tissue types. Cardiac cells from different regions of the growing embryonic heart exhibit distinct patterns of gene expression, which are thought to contribute to heart development and morphogenesis. Single cell RNA sequencing allows genome-wide analysis of gene expression at the single cell level. Here, we analyzed cardiac cells derived from early stage developing hearts by single cell RNA-seq and identified cell cycle gene expression as a major determinant of transcriptional variation. Within cell cycle stage-matched CMs from a given heart chamber, we found that CMs in the G2/M phase downregulated sarcomeric and cytoskeletal markers. We also identified cell location-specific signaling molecules that may influence the proliferation of other nearby cell types. Our data highlight how variations in cell cycle activity selectively promote cardiac chamber growth during development, reveal profound chamber-specific cell cycle-linked transcriptional shifts, and open the way to deeper understanding of pathogenesis of congenital heart disease.

    View details for DOI 10.1242/dev.173476

    View details for PubMedID 31142541

  • Human-Induced Pluripotent Stem Cell Model of Trastuzumab-Induced Cardiac Dysfunction in Patients With Breast Cancer CIRCULATION Kitani, T., Ong, S., Lam, C., Rhee, J., Zhang, J. Z., Oikonomopoulos, A., Ma, N., Tian, L., Lee, J., Telli, M. L., Witteles, R. M., Sharma, A., Sayed, N., Wu, J. C. 2019; 139 (21): 2451–65
  • A Human iPSC Double-Reporter System Enables Purification of Cardiac Lineage Subpopulations with Distinct Function and Drug Response Profiles CELL STEM CELL Zhang, J. Z., Termglinchan, V., Shao, N., Itzhaki, I., Liu, C., Ma, N., Tian, L., Wang, V. Y., Chang, A. Y., Guo, H., Kitani, T., Wu, H., Lam, C., Kodo, K., Sayed, N., Blau, H. M., Wu, J. C. 2019; 24 (5): 802-+
  • Single-Cell RNA Sequencing of Human Embryonic Stem Cell Differentiation Delineates Adverse Effects of Nicotine on Embryonic Development STEM CELL REPORTS Guo, H., Tian, L., Zhang, J. Z., Kitani, T., Paik, D. T., Lee, W., Wu, J. C. 2019; 12 (4): 772–86
  • A Human iPSC Double-Reporter System Enables Purification of Cardiac Lineage Subpopulations with Distinct Function and Drug Response Profiles. Cell stem cell Zhang, J. Z., Termglinchan, V., Shao, N., Itzhaki, I., Liu, C., Ma, N., Tian, L., Wang, V. Y., Chang, A. C., Guo, H., Kitani, T., Wu, H., Lam, C. K., Kodo, K., Sayed, N., Blau, H. M., Wu, J. C. 2019

    Abstract

    The diversity of cardiac lineages contributes to the heterogeneity of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs). Here, we report the generation of a hiPSC TBX5Clover2 and NKX2-5TagRFP double reporter to delineate cardiaclineages and isolate lineage-specific subpopulations. Molecular analyses reveal that four different subpopulations can be isolated based on the differential expression of TBX5 and NKX2-5, TBX5+NKX2-5+, TBX5+NKX2-5-, TBX5-NKX2-5+, and TBX5-NKX2-5-, mimicking the first heart field, epicardial, second heart field, and endothelial lineages, respectively. Genetic and functional characterization indicates that each subpopulation differentiates into specific cardiac cells. We further identify CORIN as a cell-surface marker for isolating the TBX5+NKX2-5+ subpopulation and demonstrate the use of lineage-specific CMs for precise drug testing. We anticipate that this tool will facilitate theinvestigation of cardiac lineage specification and isolation of specific cardiac subpopulations for drug screening, tissue engineering, and disease modeling.

    View details for PubMedID 30880024

  • Identifying the Transcriptome Signatures of Calcium Channel Blockers in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Circulation research Lam, C. K., Tian, L., Belbachir, N., Shrestha, R., Ma, N., Kitani, T., Rhee, J. W., Wnorowski, A., Wu, J. C. 2019

    Abstract

    Calcium channel blockers (CCBs) are an important class of drugs in managing cardiovascular diseases. Patients usually rely on these medications for the remainder of their lives after diagnosis. Although the acute pharmacological actions of CCBs in the hearts are well-defined, little is known about the drug-specific effects on human cardiomyocyte transcriptomes and physiological alterations after long-term exposure.This study aimed to simulate chronic CCB treatment and to examine both the functional and transcriptomic changes in human cardiomyocytes.We differentiated cardiomyocytes and generated engineered heart tissues from three human induced pluripotent stem cell (iPSC) lines and exposed them to four different CCBs-nifedipine, amlodipine, diltiazem, and verapamil-at their physiological serum concentrations for two weeks. Without inducing cell death and damage to myofilament structure, CCBs elicited line-specific inhibition on calcium kinetics and contractility. While all four CCBs exerted similar inhibition on calcium kinetics, verapamil applied the strongest inhibition on cardiomyocyte contractile function. By profiling cardiomyocyte transcriptome after CCB treatment, we identified little overlap in their transcriptome signatures. Verapamil is the only inhibitor that reduced the expression of contraction-related genes, such as myosin heavy chain and troponin I, consistent with its depressive effects on contractile function. The reduction of these contraction related genes may also explain the responsiveness of HCM patients to verapamil in managing left ventricular outflow tract obstruction.This is the first study to identify the transcriptome signatures of different CCBs in human cardiomyocytes. The distinct gene expression patterns suggest that although the four inhibitors act on the same target, they may have distinct effects on normal cardiac cell physiology.

    View details for PubMedID 31079550

  • Human Induced Pluripotent Stem Cell Model of Trastuzumab-Induced Cardiac Dysfunction in Breast Cancer Patients. Circulation Kitani, T., Ong, S. G., Lam, C. K., Rhee, J. W., Zhang, J. Z., Oikonomopoulos, A., Ma, N., Tian, L., Lee, J., Telli, M. L., Witteles, R. M., Sharma, A., Sayed, N., Wu, J. C. 2019

    Abstract

    Molecular targeted chemotherapies have been shown to significantly improve cancer patient outcomes, but often cause cardiovascular side effects that limit their use and impair patients' quality of life. Cardiac dysfunction induced by these therapies, especially trastuzumab, shows a distinct cardiotoxic clinical phenotype compared to cardiotoxicity induced by conventional chemotherapies.We employed the human induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) platform to determine the underlying cellular mechanisms in trastuzumab-induced cardiac dysfunction. We assessed the effects of trastuzumab on structural and functional properties in iPSC-CMs from healthy individuals and performed RNA-sequencing (RNA-seq) to further examine the effect of trastuzumab on iPSC-CMs. We also generated iPSCs from patients receiving trastuzumab and examined whether patients' phenotype could be recapitulated in vitro using patient-specific iPSC-CMs.We found that clinically relevant doses of trastuzumab significantly impaired the contractile and calcium handling properties of iPSC-CMs without inducing cardiomyocyte death or sarcomeric disorganization. RNA-seq and subsequent functional analysis revealed mitochondrial dysfunction and altered cardiac energy metabolism pathway as primary causes of trastuzumab-induced cardiotoxic phenotype. Human iPSC-CMs generated from patients who received trastuzumab and experienced severe cardiac dysfunction were more vulnerable to trastuzumab treatment, compared to iPSC-CMs generated from patients who did not experience cardiac dysfunction following trastuzumab therapy. Importantly, metabolic modulation with AMPK activators could avert the adverse effects induced by trastuzumab.Our results indicate that alterations in cellular metabolic pathways in cardiomyocytes could be a key mechanism underlying the development of cardiac dysfunction following trastuzumab therapy; therefore, targeting the altered metabolism may be a promising therapeutic approach for trastuzumab-induced cardiac dysfunction.

    View details for PubMedID 30866650

  • Modeling Cardiovascular Risks of E-Cigarettes With Human-Induced Pluripotent Stem Cell-Derived Endothelial Cells. Journal of the American College of Cardiology Lee, W. H., Ong, S. G., Zhou, Y., Tian, L., Bae, H. R., Baker, N., Whitlatch, A., Mohammadi, L., Guo, H., Nadeau, K. C., Springer, M. L., Schick, S. F., Bhatnagar, A., Wu, J. C. 2019; 73 (21): 2722–37

    Abstract

    Electronic cigarettes (e-cigarettes) have experienced a tremendous increase in use. Unlike cigarette smoking, the effects of e-cigarettes and their constituents on mediating vascular health remain understudied. However, given their increasing popularity, it is imperative to evaluate the health risks of e-cigarettes, including the effects of their ingredients, especially nicotine and flavorings.The purpose of this study was to investigate the effects of flavored e-cigarette liquids (e-liquids) and serum isolated from e-cigarette users on endothelial health and endothelial cell-dependent macrophage activation.Human-induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) and a high-throughput screening approach were used to assess endothelial integrity following exposure to 6 different e-liquids with varying nicotine concentrations and to serum from e-cigarette users.The cytotoxicity of the e-liquids varied considerably, with the cinnamon-flavored product being most potent and leading to significantly decreased cell viability, increased reactive oxygen species (ROS) levels, caspase 3/7 activity, and low-density lipoprotein uptake, activation of oxidative stress-related pathway, and impaired tube formation and migration, confirming endothelial dysfunction. Upon exposure of ECs to e-liquid, conditioned media induced macrophage polarization into a pro-inflammatory state, eliciting the production of interleukin-1β and -6, leading to increased ROS. After exposure of human iPSC-ECs to serum of e-cigarette users, increased ROS linked to endothelial dysfunction was observed, as indicated by impaired pro-angiogenic properties. There was also an observed increase in inflammatory cytokine expression in the serum of e-cigarette users.Acute exposure to flavored e-liquids or e-cigarette use exacerbates endothelial dysfunction, which often precedes cardiovascular diseases.

    View details for DOI 10.1016/j.jacc.2019.03.476

    View details for PubMedID 31146818

  • Large-Scale Single-Cell RNA-Seq Reveals Molecular Signatures of Heterogeneous Populations of Human Induced Pluripotent Stem Cell-Derived Endothelial Cells. Circulation research Paik, D. T., Tian, L., Lee, J., Sayed, N., Chen, I. Y., Rhee, S., Rhee, J., Kim, Y., Wirka, R. C., Buikema, J. W., Wu, S. M., Red-Horse, K., Quertermous, T., Wu, J. C. 2018

    Abstract

    Rationale: Human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) have risen as a useful tool in cardiovascular research, offering a wide gamut of translational and clinical applications. However, inefficiency of the currently available iPSC-EC differentiation protocol and underlying heterogeneity of derived iPSC-ECs remain as major limitations of iPSC-EC technology. Objective: Here we performed droplet-based single-cell RNA-sequencing (scRNA-seq) of the human iPSCs following iPSC-EC differentiation. Droplet-based scRNA-seq enables analysis of thousands of cells in parallel, allowing comprehensive analysis of transcriptional heterogeneity. Methods and Results: Bona fide iPSC-EC cluster was identified by scRNA-seq, which expressed high levels of endothelial-specific genes. iPSC-ECs, sorted by CD144 antibody-conjugated magnetic sorting, exhibited standard endothelial morphology and function including tube formation, response to inflammatory signals, and production of nitric oxide. Non-endothelial cell populations resulting from the differentiation protocol were identified, which included immature and atrial-like cardiomyocytes, hepatic-like cells, and vascular smooth muscle cells. Furthermore, scRNA-seq analysis of purified iPSC-ECs revealed transcriptional heterogeneity with four major subpopulations, marked by robust enrichment of CLDN5, APLNR, GJA5, and ESM1 genes respectively. Conclusions: Massively parallel, droplet-based scRNA-seq allowed meticulous analysis of thousands of human iPSCs subjected to iPSC-EC differentiation. Results showed inefficiency of the differentiation technique, which can be improved with further studies based on identification of molecular signatures that inhibit expansion of non-endothelial cell types. Subtypes of bona fide human iPSC-ECs were also identified, allowing us to sort for iPSC-ECs with specific biological function and identity.

    View details for PubMedID 29986945

  • Determining the Pathogenicity of a Genomic Variant of Uncertain Significance Using CRISPR/Cas9 and Human-Induced Pluripotent Stem Cells. Circulation Ma, N., Zhang, J., Itzhaki, I., Zhang, S. L., Chen, H., Haddad, F., Kitani, T., Wilson, K. D., Tian, L., Shrestha, R., Wu, H., Lam, C. K., Sayed, N., Wu, J. C. 2018

    Abstract

    Background -The progression toward low-cost and rapid next-generation sequencing has uncovered a multitude of variants of uncertain significance (VUS) in both patients and asymptomatic "healthy" individuals. A VUS is a rare or novel variant for which disease pathogenicity has not been conclusively demonstrated or excluded, and thus cannot be definitively annotated. VUS, therefore, pose critical clinical interpretation and risk-assessment challenges, and new methods are urgently needed to better characterize their pathogenicity. Methods -To address this challenge and showcase the uncertainty surrounding genomic variant interpretation, we recruited a "healthy" asymptomatic individual, lacking cardiac-disease clinical history, carrying a hypertrophic cardiomyopathy (HCM)-associated genetic variant (NM_000258.2:c.170C>A, NP_000249.1:p.Ala57Asp) in the sarcomeric gene MYL3, reported by the ClinVar database to be "likely pathogenic." Humaninduced pluripotent stem cells (iPSCs) were derived from the heterozygous VUSMYL3(170C>A) carrier, and their genome was edited using CRISPR/Cas9 to generate 4 isogenic iPSC lines: (1) corrected "healthy" control; (2) homozygous VUSMYL3(170C>A); (3) heterozygous frameshift mutation MYL3(170C>A/fs); and (4) known heterozygous MYL3 pathogenic mutation (NM_000258.2:c.170C>G), at the same nucleotide position as VUSMYL3(170C>A), lines. Extensive assays including measurements of gene expression, sarcomere structure, cell size, contractility, action potentials, and calcium handling were performed on the isogenic iPSC-derived cardiomyocytes (iPSC-CMs). Results -The heterozygous VUSMYL3(170C>A)-iPSC-CMs did not show an HCM phenotype at the gene expression, morphology, or functional levels. Furthermore, genome-edited homozygous VUSMYL3(170C>A)- and frameshift mutation MYL3(170C>A/fs)-iPSC-CMs lines were also asymptomatic, supporting a benign assessment for this particular MYL3 variant. Further assessment of the pathogenic nature of a genome-edited isogenic line carrying a known pathogenic MYL3 mutation, MYL3(170C>G), and a carrier-specific iPSC-CMs line, carrying a MYBPC3(961G>A) HCM variant, demonstrated the ability of this combined platform to provide both pathogenic and benign assessments. Conclusions -Our study illustrates the ability of clustered regularly interspaced short palindromic repeats/Cas9 genome-editing of carrier-specific iPSCs to elucidate both benign and pathogenic HCM functional phenotypes in a carrierspecific manner in a dish. As such, this platform represents a promising VUS riskassessment tool that can be used for assessing HCM-associated VUS specifically, and VUS in general, and thus significantly contribute to the arsenal of precision medicine tools available in this emerging field.

    View details for PubMedID 29914921