Abstract 15855: Dysregulation of miR-26a Induced by Electrical Stimulation Promotes Cardiac Differentiation of Human iPS Cells

Background: Induced pluripotent stem cells (iPSCs) can efficiently form functional cardiomyocytes through embryoid body (EB) differentiation in the presence of specific signals. Recent studies have demonstrated that electrical stimulation (EleS) can enhance the efficiency of cardiac differentiation of human iPSCs. This study investigates the role of microRNAs (miRNAs) involved in EleS-induced cardiac differentiation. Methods and results: iPSCs were induced to form EBs for 7 days, then treated with or without electrical stimulation ( EleS EBs or non-EleS EBs) for 1 to 10 days(1-1.5V/1.8cm,with a biphasic square pulse (5ms) at 5 Hz frequency). Spontaneous beating EleS EBs were present at 2 days into treatment but did not appear in non-EleS EBs group until day 7. Expression of cardiac transcriptional factors GATA4 and MEF2c was also significantly increased in EleS EBs as determined by qPCR, Western Blot, and immunocytochemistry analysis. MicroRNA-sequencing analysis was then used to profile the potential miRNAs responsible for EleS-induced cardiomyocyte differentiation. miR-1, miR-26a, miR-133a, miR-208, let-7c, miR-499 were found to be dysregulated in EleS EBs. However, in this research miR-26a was determined as a key miRNA by targeting the PTEN ene, which plays a critical role in regulation of cardiac differentiation genes GATA4 and MEF2c. Expression of these cardiac genes in EleS EBs was also markedly increased by regulation of miR-26a. Current research is ongoing to determine molecular mechanism involved in EleS-induced cardiac differentiation. Conclusion: miR-26a mediates up-regulation of crucial cardiac transcriptional factors GATA4 and MEF2c and promotes human iPS cell differentiation into cardiac progenitor cells by targeting PTEN gene.