Wnt/β-Catenin Stimulation and Laminins Support Cardiovascular Cell Progenitor Expansion from Human Fetal Cardiac Mesenchymal Stromal Cells

• Cells with progenitor properties can be expanded from human fetal cardiac MSCs
• Specific LNs support expansion and differentiation of cardiac MSCs
• The fetal cardiac MSCs express ISL1, PDGFR-α, and NKX2.5
• Subpopulations express the progenitor markers KDR, SSEA-1, c-KIT, and TBX18

SummaryThe intrinsic regenerative capacity of human fetal cardiac mesenchymal stromal cells (MSCs) has not been fully characterized. Here we demonstrate that we can expand cells with characteristics of cardiovascular progenitor cells from the MSC population of human fetal hearts. Cells cultured on cardiac muscle laminin (LN)-based substrata in combination with stimulation of the canonical Wnt/β-catenin pathway showed increased gene expression of ISL1, OCT4, KDR, and NKX2.5. The majority of cells stained positive for PDGFR-α, ISL1, and NKX2.5, and subpopulations also expressed the progenitor markers TBX18, KDR, c-KIT, and SSEA-1. Upon culture of the cardiac MSCs in differentiation media and on relevant LNs, portions of the cells differentiated into spontaneously beating cardiomyocytes, and endothelial and smooth muscle-like cells. Our protocol for large-scale culture of human fetal cardiac MSCs enables future exploration of the regenerative functions of these cells in the context of myocardial injury in vitro and in vivo.

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