Abstract 18196: Heme Oxygenase-1 Induction Protects Human Embryonic-derived Cardiomyocytes against Hypoxia/Reoxygenation Injury and Improves Cell Survival and Angiogenesis in vivo
Introduction: Cardiomyocytes derived from human embryonic stem cells (huESC-CMs) have the potential to remuscularize myocardial infarcts. However, few cells survive the early post-implant period. Heme oxygenase-1 (HO-1) has both cytoprotective and pro-angiogenic effects that might ameliorate this situation. We hypothesized that induction of HO-1 in huESC-CMs could improve the survival and vascularization of cellular grafts in ischemic infarct beds.
Methods: HuESC-CMs were differentiated from embryonic stem cells using defined protocols, then cultured for 24 hours with or without 25μM cobalt protoporphyrin (CoPP), a transcriptional activator of HO-1. For in vitro hypoxia/reoxygenation injury, cells were exposed to hypoxia for 16 hours, then 24 hours reoxygenation. Surviving cells were counted, HO-1 protein measured by western blot, and cellular oxidative stress gauged by CM-H2DCFDA dye and flow cytometry. For in vivo experiments, 1x107 CoPP-treated or untreated huESC-CMs were injected into infarcted rat hearts immediately after acute coronary ligation. At 1 week, cell survival was assessed by qPCR for the human Alu gene (n=5/group). Graft size and vascularization were quantified on histology using antibodies to human-specific myosin heavy chain and CD31 (n=6/group).
Results: Treating huESC-CMs with CoPP before hypoxic injury increased HO-1 protein by 54% (P<0.05), reduced reactive oxygen species 5-fold, and increased viable cell numbers by 112% vs. untreated cells (P<0.01). After in vivo implantation, infarcted hearts receiving CoPP-treated (vs. untreated) cells evidenced higher human DNA levels (P<0.001); 157% larger grafts encompassing 7.4% of total LV area (P<0.05; Fig. 1); and a 147% increase in blood-perfused human endothelial capillary density (P<0.05).
Conclusions: Pharmacologic induction of the pro-survival factor HO-1 in huESC-CMs reduces cellular oxidative stress and improves graft survival and perfusion in infarcted hearts.
- Regenerative medicine stem cells
- Stem cell therapy
- Oxidative stress
- Inhibitor of apoptosis
- Endothelial progenitor cell
- © 2010 by American Heart Association, Inc.