Abstract
Transplanted mesenchymal stem cells (MSC) release soluble factors that contribute to cardiac repair and vascular regeneration. We hypothesized that overexpression of GATA-4 enhances the MSC secretome, thereby increasing cell survival and promoting postinfarction cardiac angiogenesis. MSCs harvested from male rat bone marrow were transduced with GATA-4 (MSC(GATA-4)) using the murine stem cell virus retroviral expression system; control cells were either nontransduced (MSC(bas)) or transduced with empty vector (MSC(Null)). Compared with these control cells, MSC(GATA-4) were shown by immunofluorescence, real-time PCR, and Western blotting to have higher expression of GATA-4. An increased expression of angiogenic factors in MSC(GATA-4) and higher MSC resistance against hypoxia were observed. Human umbilical vein endothelial cells (HUVEC) treated with MSC(GATA-4) conditioned medium exhibited increased formation of capillary-like structures and promoted migration, compared with HUVECs treated with MSC(Null) conditioned medium. MSC(GATA-4) were injected into the peri-infarct region in an acute myocardial infarction model in Sprague-Dawley rats developed by ligation of the left anterior descending coronary artery. Survival of MSC(GATA-4), determined by Sry expression, was increased at 4 days postengraftment. MSC(GATA-4)-treated animals showed significantly improved cardiac function as assessed by echocardiography. Furthermore, fluorescent microsphere and histological studies revealed increased blood flow and blood vessel density and reduced infarction size in MSC(GATA-4)-treated animals. We conclude that GATA-4 overexpression in MSCs increased both MSC survival and angiogenic potential in ischemic myocardium and may therefore represent a novel and efficient therapeutic approach for postinfarct remodeling.