Abstract 16029: GSK-3β Overexpressing MSCs Enhance Angiogenesis through Vegfa Signaling Pathway
Overexpression of glycogen synthase kinase-3β (GSK-3β) in mesenchymal stem cells (MSCs) enhances the efficiency of cell based therapy (CBT) in the mouse model of myocardial infarction (MI) partially through stimulation of cardiomyocyte differentiation. Injection of MSCs overexpressing GSK-3β (GSK-3β-MSCs) also increased capillary density in the MI area compared to in mice injected with LacZ overexpressing MSCs (LacZ-MSCs, 4-fold, P<0.001). To identify paracrine factors involved in angiogenesis stimulated by GSK-3β-MSCs, mRNA was isolated from myocardium injected with GSK-3β-MSCs or LacZ-MSCs, and PCR array analysis was performed. Among 84 genes screened, subsequent RT-PCR analyses confirmed that fibroblast growth factor 1/2, Platelet factor 4, tumor necrosis factor and vascular endothelial growth factor A (Vegfa) were upregulated in the post-MI myocardium injected with GSK-3β-MSCs compared to that injected with LacZ-MSCs. GSK-3β directly upregulated Vegfa expression in MSCs in vitro, suggesting that the effect of GSK-3β is cell autonomous. In order to examine the role of Vegfa in mediating the therapeutic effect of GSK-3β-MSCs, Vegfa was downregulated with shRNA-Vegfa (GSK-3β-shVegfa-MSCs). Although all MI mice injected with GSK-3β-MSCs survived until 12 weeks, only 6 out of 10 mice injected with GSK-3β-shVegfa-MSCs survived. Capillary density was significantly greater in GSK-3β-MSCs-injected mice compared to GSK-3β-shVegfa-MSCs-injected mice. The size of MI was similarly reduced and systolic function, as evaluated by fractional shortening, was similarly improved in GSK-3β-MSCs and GSK-3β-shVegfa-MSCs injected mice compared to saline injected mice. However, myocyte cross sectional area in adjacent (267±9, 145±7μm2, P<0.001) and remote areas (230±10, 107±4μm2, P<0.001) was significantly greater and negative dP/dt (4300±300, 6400±200mmHg, p<0.001) was significantly smaller in GSK-3β-shVegfa-MSCs-injected mice compared to GSK-3β-MSCs-injected ones. These results suggest that, in CBT, stimulation of GSK-3β in MSCs induces angiogenesis and improves cardiac hypertrophy and diastolic function through paracrine mechanisms, and that the therapeutic benefit of GSK-3β-MSCs is in part mediated by Vegfa production in MSCs.
- © 2010 by American Heart Association, Inc.