About 3,000 individuals in the United States are awaiting a donor heart; worldwide, 22 million individuals are living with heart failure. A bioartificial heart is a theoretical alternative to transplantation or mechanical left ventricular support. Generating a bioartificial heart requires engineering of cardiac architecture, appropriate cellular constituents and pump function. We decellularized hearts by coronary perfusion with detergents, preserved the underlying extracellular matrix, and produced an acellular, perfusable vascular architecture, competent acellular valves and intact chamber geometry. To mimic cardiac cell composition, we reseeded these constructs with cardiac or endothelial cells. To establish function, we maintained eight constructs for up to 28 d by coronary perfusion in a bioreactor that simulated cardiac physiology. By day 4, we observed macroscopic contractions. By day 8, under physiological load and electrical stimulation, constructs could generate pump function (equivalent to about 2% of adult or 25% of 16-week fetal heart function) in a modified working heart preparation.

Background Human cardiac progenitor cells (hCPCs) may promote myocardial regeneration in adult ischemic myocardium. The regenerative capacity of hCPCs in young patients with nonischemic congenital heart defects for potential use in congenital heart defect repair warrants exploration. Methods and Results Human right atrial specimens were obtained during routine congenital cardiac surgery across 3 groups: neonates (age, <30 days), infants (age, 1 month to 2 years), and children (age, >2 to ≤13 years). C-kit+ hCPCs were 3-fold higher in neonates than in children >2 years of age. hCPC proliferation was greatest during the neonatal period as evidenced by c-kit+ Ki67+ expression but decreased with age. hCPC differentiation capacity was also greatest in neonatal right atrium as evidenced by c-kit+, NKX2–5+, NOTCH1+, and NUMB+ expression. Despite the age-dependent decline in resident hCPCs, we isolated and expanded right atrium–derived CPCs from all patients (n = 103) across all ages and diagnoses using the cardiosphere method. Intact cardiospheres contained a mix of heart-derived cell subpopulations that included cardiac progenitor cells expressing c-kit+, Islet-1, and supporting cells. The number of c-kit+–expressing cells was highest in human cardiosphere-derived cells (hCDCs) grown from neonatal and infant right atrium. Furthermore, hCDCs could differentiate into diverse cardiovascular lineages by in vitro differentiation assays. Transplanted hCDCs promoted greater myocardial regeneration and functional improvement in infarcted myocardium than transplanted cardiac fibroblasts. Conclusions Resident hCPCs are most abundant in the neonatal period and rapidly decrease over time. hCDCs can be reproducibly isolated and expanded from young human myocardial samples regardless of age or diagnosis. hCPCs are functional and have potential in congenital cardiac repair.

Background Human stem cells (CSCs) promote myocardial regeneration in adult ischemic myocardium. The regenerative capacity of CSCs in the very young patients with non-ischemic congenital heart defects has not been explored. We hypothesized that isolated neonatal-derived CSCs may have a higher regenerative ability than adult-derived CSCs and might address the structural deficiencies of congenital heart disease. Methods and Results Human specimens were obtained during routine cardiac surgical procedures from right atrial appendage tissue discarded from two age groups: neonates and adults patients. We developed a reproducible isolation method that generated cardiosphere derived cells (CDCs), regardless of starting tissue weight or age. Neonatal-derived CDCs demonstrated increased number of cardiac progenitor cells expressing c-kit+, flk-1 and Islet-1 by flow cytometry and immunofluorescence. When transplanted into infarcted myocardium, neonatal-derived CDCs had a significantly higher ability to preserve myocardial function, prevent adverse remodeling and enhance blood vessel preservation and/or formation when compared to adult CDCs. Lastly, neonatal-derived CDCs were more cardiomyogenic than adult CDCs when co-cultured with neonatal cardiomyocytes and displayed enhanced angiogenic function compared to adult CDCs. Conclusions Neonatal-derived CDCs have a strong regenerative ability when compared to adult-derived CDCs that may depend on angiogenic cytokines and an increase prevalence of stem cells. This has important implications in the potential use of CDCs in future clinical trials.