CRISPR Activation of Endogenous Genes Reprograms Fibroblasts into Cardiovascular Progenitor Cells for Myocardial Infarction Therapy.

Fibroblasts can be reprogrammed into cardiovascular progenitor cells (CPCs) using transgenic approaches, although the underlying mechanism remains unclear. We determined whether activation of endogenous genes such as Gata4, Nkx2.5, and Tbx5 can rapidly establish autoregulatory loops and initiate CPC generation in adult extracardiac fibroblasts using a CRISPR activation system. The induced fibroblasts (>80%) showed phenotypic changes as indicated by an Nkx2.5 cardiac enhancer reporter. The progenitor characteristics were confirmed by colony formation and expression of cardiovascular genes. Cardiac sphere induction segregated the early and late reprogrammed cells that can generate functional cardio-myocytes and vascular cells in vitro. Therefore, they were termed CRISPR- induced CPCs (ciCPCs). Transcriptomic analwere important to accelerate CPC formation during the early reprogramming stage. The CRISPR system opened the silenced chromatin locus, thereby allowing transcriptional factors to access their own promoters and eventually forming a positive feedback loop. The regenerative potential of ciCPCs was assessed after implantation in mouse myocardial infarction lar cells in vivo but also significantly improved contractile funcnew cell source for regenerative therapeutics.