Xu Cao

All Publications

• Mitochondrial reactive oxygen species impact human fibroblast responses to protracted γ-ray exposures. International journal of radiation biology Whitcomb, L. A., Cao, X., Thomas, D., Wiese, C., Pessin, A. S., Zhang, R., Wu, J. C., Weil, M. M., Chicco, A. J. 2024: 1-13

  Abstract

  Purpose: Continuous exposure to ionizing radiation at a low dose rate poses significant health risks to humans on deep space missions, prompting the need for mechanistic studies to identify countermeasures against its deleterious effects. Mitochondria are a major subcellular locus of radiogenic injury, and may trigger secondary cellular responses through the production of reactive oxygen species (mtROS) with broader biological implications. Methods and Materials: To determine the contribution of mtROS to radiation-induced cellular responses, we investigated the impacts of protracted γ-ray exposures (IR; 1.1 Gy delivered at 0.16 mGy/min continuously over 5 days) on mitochondrial function, gene expression, and the protein secretome of human HCA2-hTERT fibroblasts in the presence and absence of a mitochondria-specific antioxidant mitoTEMPO (MT; 5 µM). Results: IR increased fibroblast mitochondrial oxygen consumption (JO2) and H2O2 release rates (JH2O2) under energized conditions, which corresponded to higher protein expression of NADPH Oxidase (NOX) 1, NOX4, and nuclear DNA-encoded subunits of respiratory chain Complexes I and III, but depleted mtDNA transcripts encoding subunits of the same complexes. This was associated with activation of gene programs related to DNA repair, oxidative stress, and protein ubiquination, all of which were attenuated by MT treatment along with radiation-induced increases in JO2 and JH2O2. IR also increased secreted levels of interleukin-8 and Type I collagens, while decreasing Type VI collagens and enzymes that coordinate assembly and remodeling of the extracellular matrix. MT treatment attenuated many of these effects while augmenting others, revealing complex effects of mtROS in fibroblast responses to IR. Conclusion: These results implicate mtROS production in fibroblast responses to protracted radiation exposure, and suggest potentially protective effects of mitochondrial-targeted antioxidants against radiogenic tissue injury in vivo.

  View details for DOI 10.1080/09553002.2024.2338518

  View details for PubMedID 38631047

• Modeling ionizing radiation-induced cardiovascular dysfunction with human iPSC-derived engineered heart tissues. Journal of molecular and cellular cardiology Cao, X., Thomas, D., Whitcomb, L. A., Wang, M., Chatterjee, A., Chicco, A. J., Weil, M. M., Wu, J. C. 2024; 188: 105-107

  View details for DOI 10.1016/j.yjmcc.2023.11.012

  View details for PubMedID 38431383

• ETV2 Upregulation Marks the Specification of Early Cardiomyocytes and Endothelial Cells During Co-differentiation STEM CELLS Cao, X., Mircea, M., Yakala, G., van den Hil, F. E., Brescia, M., Mei, H., Mummery, C. L., Semrau, S., Orlova, V. V. 2023; 41 (2): 140-152

  Abstract

  The ability to differentiate human-induced pluripotent stem cells (hiPSCs) efficiently into defined cardiac lineages, such as cardiomyocytes and cardiac endothelial cells, is crucial to study human heart development and model cardiovascular diseases in vitro. The mechanisms underlying the specification of these cell types during human development are not well understood which limits fine-tuning and broader application of cardiac model systems. Here, we used the expression of ETV2, a master regulator of hematoendothelial specification in mice, to identify functionally distinct subpopulations during the co-differentiation of endothelial cells and cardiomyocytes from hiPSCs. Targeted analysis of single-cell RNA-sequencing data revealed differential ETV2 dynamics in the 2 lineages. A newly created fluorescent reporter line allowed us to identify early lineage-predisposed states and show that a transient ETV2-high-state initiates the specification of endothelial cells. We further demonstrated, unexpectedly, that functional cardiomyocytes can originate from progenitors expressing ETV2 at a low level. Our study thus sheds light on the in vitro differentiation dynamics of 2 important cardiac lineages.

  View details for DOI 10.1093/stmcls/sxac086

  View details for Web of Science ID 000908305000001

  View details for PubMedID 36512477

  View details for PubMedCentralID PMC9982073

• Clinical Trial in a Dish for Space Radiation Countermeasure Discovery. Life sciences in space research Cao, X., Weil, M. M., Wu, J. C. 2022; 35: 140-149

  Abstract

  NASA aims to return humans to the moon within the next five years and to land humans on Mars in a few decades. Space radiation exposure represents a major challenge to astronauts' health during long-duration missions, as it is linked to increased risks of cancer, cardiovascular dysfunctions, central nervous system (CNS) impairment, and other negative outcomes. Characterization of radiation health effects and developing corresponding countermeasures are high priorities for the preparation of long duration space travel. Due to limitations of animal and cell models, the development of novel physiologically relevant radiation models is needed to better predict these individual risks and bridge gaps between preclinical testing and clinical trials in drug development. "Clinical Trial in a Dish" (CTiD) is now possible with the use of human induced pluripotent stem cells (hiPSCs), offering a powerful tool for drug safety or efficacy testing using patient-specific cell models. Here we review the development and applications of CTiD for space radiation biology and countermeasure studies, focusing on progress made in the past decade.

  View details for DOI 10.1016/j.lssr.2022.05.006

  View details for PubMedID 36336359

• Looking on the horizon; potential and unique approaches to developing radiation countermeasures for deep space travel. Life sciences in space research Bokhari, R. S., Beheshti, A., Blutt, S. E., Bowles, D. E., Brenner, D., Britton, R., Bronk, L., Cao, X., Chatterjee, A., Clay, D. E., Courtney, C., Fox, D. T., Gaber, M. W., Gerecht, S., Grabham, P., Grosshans, D., Guan, F., Jezuit, E. A., Kirsch, D. G., Liu, Z., Maletic-Savatic, M., Miller, K. M., Montague, R. A., Nagpal, P., Osenberg, S., Parkitny, L., Pierce, N. A., Porada, C., Rosenberg, S. M., Sargunas, P., Sharma, S., Spangler, J., Tavakol, D. N., Thomas, D., Vunjak-Novakovic, G., Wang, C., Whitcomb, L., Young, D. W., Donoviel, D. 2022; 35: 105-112

  Abstract

  Future lunar missions and beyond will require new and innovative approaches to radiation countermeasures. The Translational Research Institute for Space Health (TRISH) is focused on identifying and supporting unique approaches to reduce risks to human health and performance on future missions beyond low Earth orbit. This paper will describe three funded and complementary avenues for reducing the risk to humans from radiation exposure experienced in deep space. The first focus is on identifying new therapeutic targets to reduce the damaging effects of radiation by focusing on high throughput genetic screens in accessible, sometimes called lower, organism models. The second focus is to design innovative approaches for countermeasure development with special attention to nucleotide-based methodologies that may constitute a more agile way to design therapeutics. The final focus is to develop new and innovative ways to test radiation countermeasures in a human model system. While animal studies continue to be beneficial in the study of space radiation, they can have imperfect translation to humans. The use of three-dimensional (3D) complex in vitro models is a promising approach to aid the development of new countermeasures and personalized assessments of radiation risks. These three distinct and unique approaches complement traditional space radiation efforts and should provide future space explorers with more options to safeguard their short and long-term health.

  View details for DOI 10.1016/j.lssr.2022.08.003

  View details for PubMedID 36336356

• Acoustic Fabrication of Living Cardiomyocyte-based Hybrid Biorobots. ACS nano Wang, J., Soto, F., Ma, P., Ahmed, R., Yang, H., Chen, S., Wang, J., Liu, C., Akin, D., Fu, K., Cao, X., Chen, P., Hsu, E. C., Soh, H. T., Stoyanova, T., Wu, J. C., Demirci, U. 2022

  Abstract

  Organized assemblies of cells have demonstrated promise as bioinspired actuators and devices; still, the fabrication of such "biorobots" has predominantly relied on passive assembly methods that reduce design capabilities. To address this, we have developed a strategy for the rapid formation of functional biorobots composed of live cardiomyocytes. We employ tunable acoustic fields to facilitate the efficient aggregation of millions of cells into high-density macroscopic architectures with directed cell orientation and enhanced cell-cell interaction. These biorobots can perform actuation functions both through naturally occurring contraction-relaxation cycles and through external control with chemical and electrical stimuli. We demonstrate that these biorobots can be used to achieve controlled actuation of a soft skeleton and pumping of microparticles. The biocompatible acoustic assembly strategy described here should prove generally useful for cellular manipulation in the context of tissue engineering, soft robotics, and other applications.

  View details for DOI 10.1021/acsnano.2c01908

  View details for PubMedID 35671037

• Generation of three induced pluripotent stem cell lines from hypertrophic cardiomyopathy patients carrying MYH7 mutations. Stem cell research Cao, X., Jahng, J. W., Lee, C., Zha, Y., Wheeler, M. T., Sallam, K., Wu, J. C. 2021; 55: 102455

  Abstract

  MYH7 heterozygous mutations are common genetic causes of hypertrophic cardiomyopathy (HCM). HCM is characterized by hypertrophy of the left ventricle and diastolic dysfunction. We generated three human induced pluripotent stem cell (iPSC) lines from three HCM patients each carrying a single heterozygous mutation in MYH7, c.2167C>T, c.4066G>A, and c.5135G>A, respectively. All lines expressed high levels of pluripotent markers, had normal karyotype, and possessed capability of differentiation into derivatives of the three germ layers, which can serve as valuable tools for modeling HCM in vitro and investigating the pathological mechanisms related to MYH7 mutations.

  View details for DOI 10.1016/j.scr.2021.102455

  View details for PubMedID 34352619

• Human-iPSC-Derived Cardiac Stromal Cells Enhance Maturation in 3D Cardiac Microtissues and Reveal Non-cardiomyocyte Contributions to Heart Disease CELL STEM CELL Giacomelli, E., Meraviglia, V., Campostrini, G., Cochrane, A., Cao, X., van Helden, R. J., Garcia, A., Mircea, M., Kostidis, S., Davis, R. P., van Meer, B. J., Jost, C. R., Koster, A. J., Mei, H., Miguez, D. G., Mulder, A. A., Ledesma-Terron, M., Pompilio, G., Sala, L., Salvatori, D. F., Slieker, R. C., Sommariva, E., de Vries, A. F., Giera, M., Semrau, S., Tertoolen, L. J., Orlova, V. V., Bellin, M., Mummery, C. L. 2020; 26 (6): 862-+

  Abstract

  Cardiomyocytes (CMs) from human induced pluripotent stem cells (hiPSCs) are functionally immature, but this is improved by incorporation into engineered tissues or forced contraction. Here, we showed that tri-cellular combinations of hiPSC-derived CMs, cardiac fibroblasts (CFs), and cardiac endothelial cells also enhance maturation in easily constructed, scaffold-free, three-dimensional microtissues (MTs). hiPSC-CMs in MTs with CFs showed improved sarcomeric structures with T-tubules, enhanced contractility, and mitochondrial respiration and were electrophysiologically more mature than MTs without CFs. Interactions mediating maturation included coupling between hiPSC-CMs and CFs through connexin 43 (CX43) gap junctions and increased intracellular cyclic AMP (cAMP). Scaled production of thousands of hiPSC-MTs was highly reproducible across lines and differentiated cell batches. MTs containing healthy-control hiPSC-CMs but hiPSC-CFs from patients with arrhythmogenic cardiomyopathy strikingly recapitulated features of the disease. Our MT model is thus a simple and versatile platform for modeling multicellular cardiac diseases that will facilitate industry and academic engagement in high-throughput molecular screening.

  View details for DOI 10.1016/j.stem.2020.05.004

  View details for Web of Science ID 000539161800012

  View details for PubMedID 32459996

  View details for PubMedCentralID PMC7284308