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Human pluripotent stem cells (hPSCs), including human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs), have the ability of self-renewal and the capacity to differentiate into cells of the three embryonic germ layers 1,2. Due to these characteristics, hPSCs provide a valuable and unlimited source for the generation and scalable production of disease-relevant cell types for modeling human disease 3-5, for high-throughput drug screening and toxicity assays 6,7 and potentially for clinical applications 8. Generation of cardiomyocytes from hPSCs provides the opportunity to specifically investigate the mechanisms of complex human cardiovascular diseases and their possible treatments, previously beyond the scope of our capabilities due to the lack of relevant animal models and/or the availability of affected primary tissues.
All of the aforementioned applications of hPSCs necessitate the production of massive numbers of highly enriched and functional cardiomyocytes. Thus, the availability of an efficient, reproducible and scalable in vitro cardiac differentiation protocol suitable for multiple hPSC lines is crucial. Conventional cardiomyocyte differentiation protocols have employed different strategies such as embryoid body formation 9, co-culture techniques 10, induction with cocktails of cytokines 11 and protein transduction methods 12. In spite of advances in these techniques, most still suffer from poor efficiency, require expensive growth factors, or offer limited universality when attempting to use multiple hPSC lines. To date, these challenges have set limits to the production of hPSC-derived cardiomyocytes for cell therapy studies in animal models, as well as in the pharmaceutical industry for drug discovery 13. Therefore, the development of robust and affordable techniques for large-scale production of functional hPSC-derived cardiomyocytes in scalable culture systems would largely facilitate their commercial and clinical applications.
In this manuscript, we report the development of a cost-effective and integrated cardiac differentiation system with high efficacy, reproducibility and applicability to hESCs and hiPSCs generated from a variety of sources and culture methods, including a method for the large-scale production of highly enriched populations of hPSC-derived cardiomyocytes using a bioreactor. Additionally, we have optimized this protocol for hPSC lines not adapted to feeder free and/or single cell culture, such as newly established hiPSCs or large cohorts of hPSC lines relevant to analysis of disease mechanism.