Abstract 65: Latrophilin-2 is a Specific Cell-surface Marker for Cardiac Progenitor Cells and Specifies Cardiac Lineage Commitment and Development

Abstract

Backgrounds: The identification of a lineage-specific marker plays a pivotal role in understanding developmental process and is utilized to isolate a certain cell type with high purity for the therapeutic purpose. We here report a new cardiac-specific marker, and demonstrate its functional significance in the cardiac development. Methods and Results: When mouse pluripotent stem cells (ES and iPS cells) were stimulated with BMP4, Activin A, bFGF and VEGF, they differentiated into cardiac cells. To screen cell-surface expressing molecules on cardiac progenitor cells compared to undifferentiated mouse iPS and ES cells, we isolated Flk1+/PDGFRa+ cells at differentiation day 4 and performed microarray analysis. Among candidates, we identified a new G protein-coupled receptor, Latrophilin-2 (LPHN2) whose signaling pathway and its effect on cardiac differentiation is unknown. In sorting experiments under cardiac differentiation condition, LPHN2+ cells derived from pluripotent stem cells strongly expressed cardiac-related genes (Mesp1, Nkx2.5, aMHC and cTnT) and exclusively gave rise to beating cardiomyocytes, as compared with LPHN2- cells. LPHN2-/- mice revealed embryonically lethal and huge defects in cardiac development. Interestingly, LPHN2+/- heterozygotes were alive and fertile. For the purpose of cardiac regeneration, we transplanted iPS-derived LPHN2+ cells into the infarcted heart of adult mice. LPHN2+ cells differentiated into cardiomyocytes, and systolic function of left ventricle was improved and infarct size was reduced. We confirmed LPHN2 expression on human iPS and ES cell-derived cardiac progenitor cells and human heart. Conclusions: We demonstrate that LPHN2 is a functionally significant and cell-surface expressing marker for both mouse and human cardiac progenitor and cardiomyocytes. Our findings provide a valuable tool for isolating cardiac lineage cells from pluripotent stem cells and an insight into cardiac development and regeneration.