Abstract 5368: Igf +hgf Enhance Sca-1+/cd31− Cell Therapy in Hearts with Postinfarction Lv Remodeling
Insulin-like growth factor 1 (IGF-1) and hepatocyte growth factor (HGF) are two potent cell survival factors in response to hypoxia and oxidative stress. We have previously shown that transplantation of Sca-1+/CD31− cells can improve LV function in hearts with acute myocardial infarction (AMI) although the engraftment rate was low. We hypothesized that supplementation of IGF-1 and HGF at delivery of cellular therapy can enhance the beneficial effects of Sca-1+/CD31− cells in the injured heart by increasing engraftment rate and endogenous cardiac cell survival. Adenovirus nuclear LacZ-labeled Sca-1+/CD31− cells (1x106) were injected into the ischemic area after LAD ligation in BalbC mice. Recombinant mouse IGF-1+HGF (100ng) was added to the cell suspension prior to the injection. The LV function (ECHO) and in vivo myocardial bioenergetics (31P-NMR spectroscopy) were assessed 4 weeks after AMI and cell transplantation. Normal mice (Normal, n=6), and 2 control groups of LAD ligation (MI, n=6), and MI plus Sca-1+/CD31− cell transplantation (Cell, n=6), were compared to AMI mice with Sca-1+/CD31− cells transplantation plus IGF-1+HGF (Cell+IGF-1+HGF, n=6). Sca-1+/CD31−cells formed viable grafts and improved LV contractile function (EF: Control, 53.3+/−3.2; MI, 18.9+/−3.9; Cell, 29.1+/−5.1, p<0.05) and myocardial bioenergetics (PCr/ATP: Control, 2.13+/−0.09; MI, 1.21+/−0.09; Cell, 1.72+/−0.12; p<0.01). IGF+HGF significantly further enhanced the benefits of the cell transplantation as evidenced by significantly increased EF to 38.3+/−3.1% (p<0.05), which was accompanied by a higher cell engraftment rate (p<0.05). Using the in vitro co culture of Sca-1+/CD31− cells with HL-1 cells labeled by Vybrant CFDA SE cell tracer kit, we observed both IGF+HGF and Sca-1+/CD31− cells can inhibit TNFα and hypoxia induced HL-1 cell apoptosis (Control, 7+/−1%; TNFα, 24+/−1%; IGF+HGF+TNFα, 10+/−1%; n=6, P<0.001) and caspase 3 expression. These data demonstrate that IGF-1+HGF could serve as an adjuvant to cell transplantation for myocardial restoration.