Abstract 15510: Generation of the Cardiac Valve Lineage From Human Pluripotent Stem Cells

Abstract

Background: Heart valves are living structures whose sophisticated functions are mediated by a specialized population of valvular interstitial cells (VICs). Given their central role in valve homeostasis, VICs represent a promising cell population for studying valve diseases and developing novel therapies to treat them. Herein, we describe the generation of VIC-like cells from human pluripotent stem cells (hPSCs). Methods and Results: Using a previously established protocol, we first generated endocardial cells from cardiovascular mesoderm. Within this endocardial population, we identified a subset of cells — marked by the expression of PDGFRβ — that express valvular endocardial cell (VEC) markers and demonstrate VEC-like functional properties, namely the ability to generate calcium transients in response to ATP and the ability to undergo endothelial-to-mesenchymal transition (EndoMT). Through stage-specific manipulation of developmental signaling pathways, we established a protocol that promotes the development of VIC-like cells from these hPSC-derived VEC progenitors (Figure 1A). The cells thus generated transcriptionally matched primary human fetal VICs by scRNAseq. When embedded in a tissue-engineered scaffold, hPSC-VICs secreted collagen and glycosaminoglycans, and demonstrated compact tissue organization analogous to that of native valve leaflets (Figure 1B, C). Finally, we show that VICs generated from an hPSC line with a Noonan syndrome mutation displayed excessive endocardial cell proliferation, diminished EndoMT, and dysregulated pERK activity, recapitulating key aspects of the disease. Conclusions: Together, the findings presented in this report provide a reproducible method for the scaled generation of bona fide VICs from hPSCs. The generation of hPSC-VICs addresses an important gap in the field and provides a platform to study valvulogenesis and heart valve disease, as well as a novel avenue for heart valve tissue engineering.