Cardiac progenitor cells (CPCs) are being developed as a promising treatment for heart failure. Although clinical trials have predominantly used donor cardiac biopsies to derive CPCs, a better solution could be to use previously cryopreserved human heart tissue. This would enable timely and convenient access to healthy and young heart samples for CPC production. However, few studies have attempted to isolate CPCs from previously cryopreserved heart tissue. In this study, we isolated CPCs from eight nondiseased human heart samples previously cryopreserved as part of the Sydney Heart Bank. Resulting cells were strongly positive for known fibroblast (DDR2, Vimentin), mesenchymal/CPC (PDGFRα, CD90) markers, and for pluripotency genes (SOX2, NANOG, MYC, KLF4), whereas being negative for the pan-hematopoietic marker (CD45). Outgrowth cells from aged hearts had decreased proliferative and self-renewing capacity that correlated with shorter telomere lengths compared with cells from young hearts. No telomerase activity was detected in any cells isolated. Colony-forming assays and fluorescence-activated cell sorting were used to enrich PDGFRα+/CD90+/CD31- CPCs. Multipotent potential was confirmed using in vitro differentiation assays with smooth muscle (MYH11+), endothelial cell (vWF+), and cardiomyocyte-like (cTnT+, α-actinin+) cell formation. Single cell assays demonstrated clonogenicity of PDGFRα+ CPCs with maintenance of prolonged self-renewing capacity (>2 months), and pluripotency gene expression at both early and late culture passages. Our results demonstrate that multipotent PDGFRα+ CPCs can be harvested and expanded from previously banked cryopreserved human heart samples. These data support cardiac tissue banking as a strategy for improved access to CPCs for future clinical therapies.
Keywords: cardiac progenitor cells; frozen tissue; human heart; multipotent; stem cells.