Abstract P418: Transcriptomic And Genomic DNA Accessibility Dynamics During Differentiation Of Induced Pluripotent Stem Cells Derived Smooth Muscle Cells And Acquisition Of Contractile Phenotype

Abstract

Introduction: Smooth muscle cells (SMCs) capacity to phenotype switching between proliferative and quiescent (contractile) is a widely studied mechanism in cardiovascular disease. Primary SMCs tend to lose many physiological features in culture, which makes the study of their contractile function challenging. Recently, an optimized protocol of induced pluripotent stem cells (iPSCs) differentiation into contractile SMCs was described. Here we aimed at defining the transcriptomic and open chromatin dynamics during the acquisition of SMCs phenotypes. Methods: We differentiated 4 human iPSC lines (2 males, 2 females) towards either contractile (Repsox induced) or synthetic (PDGF-BB/TGF-β induced) SMC phenotypes using a 24-days protocol. We performed RNA-Seq and assay for transposase accessible chromatin (ATAC)-Seq at 5 time points of differentiation. We analyzed gene expression profiles and compared them to existing dataset of human aorta by principle component analyses (PCA) and gene set enrichment analyses using GO terms. Results: iPSCs derived SMCs showed expected morphology and positive expression of SMC markers. Synthetic SMCs (SSMCs) exhibited greater capacity of proliferation, migration and lower calcium release capacity, compared to contractile SMCs (CSMCs). RNA-Seq results showed that multiple genes involved in the contractile function of arteries, including myosin light chain kinase (MYLK) and angiotensin type 1 receptor ( AGTR1 ) genes were highly expressed in CSMCs compared to SSMCs. Overall, CSMCs conserved SMC properties beyond 24 days and their gene expression profile clustered near human aorta. During late differentiation stages, CSMCs showed an upregulation of genes involved in cardiovascular system development, whereas genes involved in cell stress were upregulated in SSMCs. Conclusions: We describe global genomic profiles of iPSCs derived CSMCs that presented comparable gene expression profiles to mature artery tissue. Combination with upcoming DNA accessibility maps is expected to allow the functional exploration of genetic risk variation involved in several arterial diseases involving the impairment of the SMCs contractile function.