Abstract 16646: Successful Expansion and Bioscaffolding of Clonogenic Cardiac Pericyte-Like Cells From Infants Affected by Congenital Heart Disease

Introduction: Current prostheses for correction of congenital heart disease (CHD) are unable to match the growth of an infant’s heart and deteriorate due to matrix degradation. Biological scaffolds integrated with progenitor cells able to grow and renew the prosthetic matrix may provide durable correction of CHD. We investigate the plasticity of cardiac pericyte-like cells obtained from CHD infants and their compatibility with a clinically certified prosthetic graft (CorMatrix). Methods&Results: CD34+ CD31- Pericytes (CPs) were immuno-sorted from myocardial specimen leftovers (n=13) of neonates and infants undergoing repairs of CHD. CPs were expanded and characterized for surface antigens, plasticity toward cardiovascular lineages, clonogenicity and ability to colonize a CorMatrix patch. We successfully expanded CPs in culture for several passages to reach a high number of cells (>20 million at P5). Flow cytometry of expanded cells at P4 (n=7) indicates a mesenchymal phenotype (CD105, CD44, CD90) but very low expression of endothelial and hematopoietic markers. Fluorescent microscopy of CP lines (n=6) show abundant expression of pericyte (NG2, vimentin, PDGFR-β) and stemness markers (Oct-4, SOX-2, Nanog). By single-cell sorting, we demonstrated the clonogenic capacity of CPs. When cultured with differentiation media, CPs failed to acquire mature endothelial proteins (VEGFR2, vWF, VE-Cadherin), while they acquired markers of synthetic VSMCs (α-SMA, Calponin, non-muscle myosin B, RBP1). Moreover, when grown under cardiomyocyte inductive conditions, CPs acquired TBX5, CACNA1C and Connexin43 at the transcriptional level. Finally, we succeed in growing CPs on a CorMatrix membrane. Fluorescent microscopy showed vimentin-positive CPs not only at the surface, but also within the patch, indicating ability to colonize, grow and form a cellularized scaffold. Conclusions: We show for the first time the possibility of expanding a clonogenic population of bona fide pericytes from hearts of CHD patients, differentiating them in cardiovascular cells, and growing them within extracellular matrices that are currently used in cardiac surgery. These data open new avenues for cellular functionalization of prosthetic material to correct CHD.