Background: Vascular endothelial growth factor (VEGF) is a promising reagent for inducing myocardial angiogenesis. Skeletal myoblast transplantation has been shown to improve cardiac function in chronic heart failure models by regenerating muscle. We hypothesized that transplantation of VEGF-expressing myoblasts could effectively treat acute myocardial infarction by providing VEGF-induced cardioprotection through vasodilatation in the early phase, followed by angiogenesis effects in salvaging ischemic host myocardium combined with the functional benefits of newly formed, skeletal myoblast-derived muscle in the later phase.
Methods and results: Primary rat skeletal myoblasts were transfected with the human VEGF(165) gene using hemagglutinating virus of Japan-liposome with >95% transfection efficiency. Four million of these myoblasts (VEGF group), control-transfected myoblasts (control group), or medium only (medium group) was injected into syngeneic rat hearts 1 hour after left coronary artery occlusion. Myocardial VEGF-expression increased for 2 weeks in the VEGF group, resulting in enhanced angiogenesis without the formation of tumors. Grafted myoblasts had differentiated into multinucleated myotubes within host myocardium. Infarct size (33.3+/-1.4%, 38.1+/-1.4%, and 43.7+/-1.6% for VEGF, control, and medium groups, respectively; P=0.0005) was significantly reduced with VEGF treatment, and cardiac function improved in the VEGF group (maximum dP/dt: 4072.0+/-93.6, 3772.5+/-101.1, and 3482.5+/-90.6 mm Hg/s in the 3 groups, respectively; P=0.0011; minimum dP/dt: -504.2+/-68.5, -2311.3+/-57.0, and -2124.0+/-57.9 mm Hg/s, respectively; P=0.0008).
Conclusions: This combined strategy of cell transplantation with gene therapy could be of importance for the treatment of acute myocardial infarction.