Comparison of cardiogenic potential of induced Pluripotent Stem Cells (iPSCs) generated from murine various tissues: the role of epigenetic memory in reprogramming
Authors: Qi Xiao , Wang Jiapeng , Kantor Taylor , Huang Wei , Cai Wenfeng , Liang Jialiang , Paul Christian , Freed Darren , Wang Yigang 
Published: November 2023

IntroductionCoronary artery disease (CAD), i.e. myocardial infarction and ischemic cardiomyopathy, is the global leading cause of death. Ischemia leads to loss of functional cardiomyocytes, which contributes to a variety of types of heart failure. Although conventional treatments including pharmacological therapy and coronary revascularization procedures exist, novel therapeutic approaches are still needed. The prospect of stem‐cell‐based therapies might have considerable therapeutic potential. Induced pluripotent stem cells (iPSCs) can be generated from a variety of somatic cells as a potential resource of replacement cells, making them ideal cellular models to provide a renewable source of cardiomyocytes for cell‐based therapy. However, an ideal cell type with superior cardiomyocyte (CM) potential has yet to be identified. Masseter muscle cells (MMC) characterized as Isl‐1+ cells, a genetic marker associated with stem and progenitor states, also contribute to various cardiovascular lineages and have similar embryological origins. We postulate the regenerative potential of masseter muscle cell lineages may yield valuable developmental and clinical insights in the identification of a cell source capable of enhanced cardiomyocyte differentiation and may be used in cell‐based therapy. This study aims to study the role of epigenetic memory in the cardiogenic potential of different lineages of iPSC.MethodsA variety of cell sources including masseter muscle cells (MMC), dermal fibroblasts (Fib), bone marrow mesenchymal cells (BMC), and Trunk skeletal muscle cells (TMC) from mouse were isolated. These cell sources were then transfected with Yamanaka's factors (Oct4, Sox2, c‐Myc, and Klf‐4) to generate four lineages of iPSCs. These four iPSC cell lineages were differentiated into iPSC‐CMs via 3‐D culture protocols and analyzed for differences in their differentiation potential as well as the efficiency of differentiation. Cardiomyocytes differentiation was analyzed by spontaneous contractions, immunostaining, flow cytometry test, and patch clamp. The epigenetic signatures of somatic cells, iPSCs, and derived Cardiomyocytes were analyzed by Real‐time PCR. Methylation study was used to evaluate epigenetic memory of four lineages of iPSCs.ResultsSpontaneous beating was observed in 80% colonies of MMC‐derived iPSC‐cardiomyocytes (MMC‐CM), which was significantly higher than other groups. Cardiac genes Isl‐1, Nkx2.5, and GATA4 were also significantly upregulated in MMC‐CM. MMC‐CM exerted robust cardiac functional phenotype, indicated by enhanced contractility and electrophysiological properties. Low methylation levels of the cardiac mesodermal gene (Isl‐1) in MMC and M‐iPSC were similar to neonatal cardiomyocytes and were maintained in MMC‐CM. Cardiac genes were epigenetically silenced in other somatic cells.ConclusioniPSCs derived from masseter muscle cell sources have better cardiogenic differentiation capabilities than other somatic cell sources. Epigenetic memory significantly contributes to the prominent cardiogenic potential of masseter‐derived iPSCs.Support or Funding InformationNational Institutes of Health grants (HL110740)