Abstract 12089: Human Umbilical Cord Blood Cells Secrete Growth Factors and Cytokines that Inhibit Hypoxic-induced Apoptosis in Human Coronary Artery Endothelial Cells and Cardiac Myocytes by Activation of the Survival Proteins Akt and Bcl-2
We have demonstrated in acute myocardial infarctions that Human Umbilical Cord Blood Mononuclear Cells (HUCBC), which contain hematopoietic, endothelial and mesenchymal stem cells, reduce infarction size by >50% and preserve LV contractility. We hypothesized that the beneficial effects are due to HUCBC secretion of biologic factors that activate survival proteins in cardiac endothelial cells and myocytes. We determined by protein microarrays (N=10 exp.) the growth factors and anti-inflammatory cytokines secreted by HUCBC into culture media during 12-24 hours of 1% O2. We then determined by Western blots (N=10 exp.) the effects of cell free media from hypoxic conditioned HUCBC (HU-CM) on the activation of the cell survival proteins Akt and Bcl-2 in human coronary artery endothelial cells and cardiac myocytes in culture during 24 hrs of 1% O2. We also determined in 8 separate exps. endothelial and myocyte apoptosis by caspase 3 and Annexin-V determinations. HUCBC secreted angiopeptin 1 and 2, fractalkine, hepatocyte growth factor, insulin-like growth factor, vascular endothelial cell growth factor, interluekin-4, and tissue inhibitor of metalloproteinase during normoxia and increased secretion of each of these factors by 100 to >10,000% in concentrations from 30 to 60,000 pg/mL during 1% O2 (p<0.001). HU-CM increased Akt phosphorylation/ activation by > 60% and Bcl-2 expression by >25% in endothelial cells and myocytes subjected to 24 hrs of 1% O2 in comparison with cells treated without HU-CM in 1% O2 where p-Akt and Bcl-2 decreased (p<0.01). HU-CM also significantly decreased caspase 3 expression and decreased hypoxic-induced endothelial cell and cardiac myocyte apoptosis by >30% in comparison with cells cultured without HU-CM (p<0.01). Inhibition of Akt activation in endothelial cells and myocytes by the sensitive and specific inhibitor API-1 during 24 hr of hypoxia in 5 separate experiments nearly completely prevented HU-CM reduction of caspase 3 expression and apoptosis. We conclude that HUCBC secrete growth factors and anti-inflammatory cytokines during hypoxia that activate Akt and Bcl-2 in cardiac endothelial cells and myocytes that significantly limit apoptosis. In this manner, HUCBC can limit acute myocardial infarction size.
- © 2012 by American Heart Association, Inc.