Background: Human adult c-kit+ cardiac stem cells (CSCs) alleviates post-myocardial infarction left ventricle dysfunction in animal models and a Phase I clinical study. The regenerative capacity of CSCs in the very young patients with non-ischemic congenital heart defects has not been explored, even in the most surgically challenging Hypoplastic Left Heart Syndrome (HLHS) patients. We hypothesized that isolated neonatal-derived ckit+ CSCs have higher regenerative abilities than adult-derived CSCs and might address the anatomical deficiency of HLHS myocardium.
Methods and Results: Human specimens were obtained during routine cardiac surgical procedures from right atrial appendage tissue discarded from 2 age groups: neonates and adults patients. We developed a reproducible isolation method that generated c-kit+ cells using immune-activated magnetic bead selection, regardless of the initial weight or age. More than 85% ckit+ cells were isolated from both groups and these cells were negative for tryptase, collagen, CD45, CD34 and CD31. Single cell proliferation assay showed neonatal ckit+ cells are significantly more proliferative compare to adult ckit+ cells. Neonatal c-kit+ cells showed significantly higher telomere length (p=0.0286) compare to Adult. The neonatal-derived c-kit+ cells secreted higher levels of VEGF-A, ANG, and SDF-1α when compared to adult-derived c-kit+ cells. When transplanted into infarcted myocardium, neonatal-derived c-kit+ cells had a significantly higher ability to preserve myocardial function, prevent adverse remodeling, and enhance blood vessel preservation when compared to adult-derived c-kit+ CSCs. . Treatment with Neonatal-derived ckit+ cells also augmented the preservation/formation of neovessels (isolectin B4) and arterioles (α-SMA) compared to adult-derived ckit+ cells
Conclusions: Neonatal-derived c-kit+ cells have a strong regenerative ability when compared with adult-derived c-kit+ cells that may depend on angiogenic cytokines. This has important implications in the potential use of CSCs in future HLHS clinical trials.