Abstract 17802: Ips Cells -derived Cardiac Progenitors Induce Dramatic Cardiac Regeneration and Improve Function by Cxcr4 Signaling Pathway in Infarcted Myocardium

Abstract

Background: The participation of endogenous cardiac stem/progenitor cells is limited in restoring cardiac structure and function in the ischemic myocardium which is further aggravated by poor survival and propagation of transplanted stem cells of different origin in the infarcted heart. The goal of this study was to explore the survival and engraftability of newly discovered induced pluripotent stem cells (IPS) in the myocardium following infarction (MI). Methods and Results: Integration free iPS were generated from myoblasts and characterized. Cardiac progenitors (CPs) were created by treatment with a small molecule. CPs proliferation was assessed by BrdU labeling; Differentiation by both RT-PCR and immunofluorescent staining for cardiac markers Nkx2.5, actinin, and -MHC. Gene expression profiling was performed using Affymetrix array. In vivo studies were carried out by injecting CPs or nontreated IPS (3x105), into mouse model of permanent LAD. Echocardiography, histological parameters, TUNEL assay and capillary vessel density were measured 6 weeks post transplantation. Treatment of IPS with a small molecule upregulated Nkx2.5 and maintained up to 4 weeks (p<0.01 vs nontreated IPS). Expression of actinin and -MHC was also detectable at 3 weeks. Increased proliferative activity (p<0.01) evaluated by cell proliferation and Brdu assay was observed. Significant CPs survival and reduced apoptosis were noticed in the small molecule treated iPSC compared to nontreated and/or saline group. Enhanced ejection fraction and fractional shortening (p< 0.05) was observed 6 weeks post transplantation. Interestingly there was 2-3 fold upregulation of chemokines including CCL7, CXCR2, CXCR5. miR Microarray analysis showed upregulation of cardiac specific mir-133,762. Western blot analysis showed increased phospho-Akt levels as compared to nontreated IPSC (p<0.01). Survival and differentiation properties of CPs were abolished by concomitant treatment of IPS with CXR4 blocker (p<0.05). Conclusion: This study provides a novel strategy for generating CPs and their enhanced survival, engraftment and differentiation with the treatment of cardiogenic small molecule post transplantation in the infarcted myocardium through CXCR4 signaling pathway.