LAUSR

With the growing field of myocardial repair through transplantation of cardiomyocytes (CM) derived from human induced pluripotent stem cells (iPSC) calls for a method for reducing fibrotic tissue development at the site of cell transplantation. We tested the hypothesis of whether transplanting CMs derived from DNA damage-free (DdF) iPSCs could reduce the recruitment of myofibroblasts and reduce fibrosis at the site of transplantation. Transcription factor p53 functions are DNA damage-dependent: induce apoptosis in DNA damaged cells while promoting cell cycle in normal cells. Utilizing this discriminating nature of p53 we selected iPSCs that are DdF and differentiated them into CMs. Control CMs (Ctrl-CM) and DdF-CMs were tested for transplantation induced fibrosis in a mouse model. The inflammatory markers such as accumulation of ROS, superoxide and DNA damage were significantly reduced in DdF cells. RNA sequencing revealed that, in DdF-CMs, the inflammatory and fibrosis signaling pathways are significantly different compared to Ctrl-CMs. Transplantation of both CMs into the myocardium of ischemia-induced mice resulted in fibrosis around the transplantation site. However, the fibrotic area around transplanted sites and total fibrosis were significantly reduced in mice hearts that received DdF-CMs as evidenced by collagen accumulation and Sirus red staining of fibrotic tissue. Importantly, the number of myofibroblasts at the site of DdF-CM transplantation was significantly reduced compared to Ctrl-CM sites. In an in vitro migration study, fibroblasts preferentially migrated towards the Ctrl-CMs. Human fibroblast treatment with DdF-CM exosomes (DdF-Exo) resulted in reduced expression of fibrotic markers than Ctrl-CM exosomes (Ctrl-Exo) treatment. miRNA analysis in exosomes showed that the anti-inflammatory miR-26a is upregulated and the inflammatory miRNA101 is downregulated in DdF-Exo. Overexpression of miR-101 mimic in DdF-Exo abrogated the anti-fibrotic potential property of DdF-Exo. Our results clearly demonstrate that DdF-CMs has anti-fibrotic potential. Transplanting DdF-CMs attracted reduced myofibroblast to the engraft site and Ctrl-CMs transplantation induce fibrosis through the expression of exosomal miR-101.