Concurrent Isolation of 3 Distinct Cardiac Stem Cell Populations From a Single Human Heart Biopsy

Rationale: The relative actions and synergism between distinct myocardial-derived stem cell populations remain obscure. Ongoing debates on optimal cell population(s) for treatment of heart failure prompted implementation of a protocol for isolation of multiple stem cell populations from a single myocardial tissue sample to develop new insights for achieving myocardial regeneration. Objective: Establish a robust cardiac stem cell isolation and culture protocol to consistently generate 3 distinct stem cell populations from a single human heart biopsy. Methods and Results: Isolation of 3 endogenous cardiac stem cell populations was performed from human heart samples routinely discarded during implantation of a left ventricular assist device. Tissue explants were mechanically minced into 1 mm(3) pieces to minimize time exposure to collagenase digestion and preserve cell viability. Centrifugation removes large cardiomyocytes and tissue debris producing a single cell suspension that is sorted using magnetic-activated cell sorting technology. Initial sorting is based on tyrosine-protein kinase Kit (c-Kit) expression that enriches for 2 c-Kit(+) cell populations yielding a mixture of cardiac progenitor cells and endothelial progenitor cells. Flowthrough c-Kit(-) mesenchymal stem cells are positively selected by surface expression of markers CD90 and CD105. After 1 week of culture, the c-Kit(+) population is further enriched by selection for a CD133(+) endothelial progenitor cell population. Persistence of respective cell surface markers in vitro is confirmed both by flow cytometry and immunocytochemistry. Conclusions: Three distinct cardiac cell populations with individualized phenotypic properties consistent with cardiac progenitor cells, endothelial progenitor cells, and mesenchymal stem cells can be successfully concurrently isolated and expanded from a single tissue sample derived from human heart failure patients.