ENHANCING CARDIAC TRANSDIFFERENTIATION OF FIBROBLASTS USING SINGLE-CELL TRANSCRIPTOMICS ANALYSIS AND HIGH-THROUGHPUT CHEMICAL LIBRARY SCREENING APPOACHES

Abstract

Cardiac transdifferentiation could potentially be used to treat acute myocardial infarction, but it is hampered by the lack of effective experimental protocols. By performing high-throughput chemical library screening, we serendipitously discovered that dimethyl sulfoxide (DMSO) itself improves the efficiency of cardiac transdifferentiation. DMSO treatment increased the percentage of cTnT+ and αMHC-mCherry+ cells by about 4-fold and 6-fold, respectively, and induced higher expression of cardiac genes. Further validations suggest that DMSO could function co-linearly with TGF-β or MEK/ERK signalling pathways, although this remains to be proven empirically. Next, single-cell transcriptomic studies revealed trajectory of cardiac transdifferentiation which includes an unstable intermediate subpopulation that ultimately progresses into three distinct terminal subpopulations - Monocle State 8, 10 and 12. Cells from Monocle State 8 and 12 expressed gene signature resembling fibroblasts and mature cardiomyocytes, respectively. Interestingly, cells from Monocle State 10 possess gene signature of both cardiac and fibroblasts, suggesting incomplete transdifferentiation into cardiomyocytes.