Abstract 212: Hydrogen Peroxide Acutely Stimulates Cardiogenic Gene Expression in Cardiac Progenitor Cells
Following acute myocardial infarction, billions of myocytes are lost to cell death. The damage is regional and lost cells are replaced with a collagen scar. One potential therapy to delay or prevent progression into heart failure is regeneration of the damaged myocardium through cell therapy with cardiac progenitor cells (CPC). Reactive oxygen species, specifically hydrogen peroxide, elicit varying responses from different stem/progenitor cells. In the present studies, we sought to determine the effect of acute H2O2 treatment on CPC survival and differentiation. CPCs were isolated and cultured with leukemia inhibitory factor (LIF) to retain their stem-like qualities. CPCs were allowed to differentiate in the absence of LIF for up to 5 days + H2O2. H2O2 (100μM) significantly increased expression of the smooth muscle marker, alpha smooth muscle actin (αSM) by Day 2 as compared to time-matched controls (Ctl: 1.8+1.3 vs 100 μM: 8.5+1.1; p<0.001; N=3). We also observed a trend for an increase in smooth muscle 22 alpha (SM 22α) gene expression by Day 2. Interestingly, by Day 5 the stimulatory effect of 100 μM H2O2 treatment on α SM and SM 22α was reversed and significantly decreased compared to Day 2 (D5: α SM: 0.43+0.05, SM 22α: 0.41+0.2 vs. D2: SM 22α: 10.58+2.3; p<0.01; N=3-4). Evaluation of the endothelial marker VEGFR-2 (Flk-1) showed a trend for an increase in gene expression by Day 2 following 100 μM H2O2 treatment compared to the time-matched control. We also observed an anti-apoptotic effect on CPCs following serum removal, in which 2 days of 100μM H2O2 pretreatment lead to approximately a 55% decrease in cell death compared to untreated CPCs (Ctl: 19.1+2.4 vs 100 μM: 10.5+1.7; p<0.05; N=3-4). The protective effect of the H2O2 pretreatment could be attributed to an increase in anti-oxidative enzymatic capacity in CPCs. There was a trend for an increase in catalase gene expression. In conclusion, our results showed that acute H2O2 preconditioning exerted a stimulatory effect on smooth muscle gene expression and an anti-apoptotic effect compared to time-matched Control CPCs. Furthermore, acute H2O2 preconditioning may aid in directing CPC differentiation towards a vascular phenotype and angiogenesis in the infarcted myocardium, which may prevent or delay heart failure.
- © 2012 by American Heart Association, Inc.