Long-term effects of bone marrow mononuclear cell transplantation on left ventricular function and remodeling in rats

This study was performed to evaluate the long-term effect on left ventricular function and remodeling in a rat model of bone marrow cell transplantation (BMT) into acute infarcted myocardium. After myocardial infarction was induced in inbred Lewis rats by left anterior descending artery ligation, the ischemic area was directly injected with saline, peripheral blood mononuclear cells (PB-MNCs) or bone marrow mononuclear cells (BM-MNCs). Cardiac function and structure were evaluated by echocardiography before the operation, and on day 1 and 2 months post-infarct. The collagen content, the number of vessels and the vasculogenesis were examined by histology and immunohistochemistry. We found at 2 months post-infarct, BMT significantly improved cardiac systolic function and recovered diastolic function. Transplantation of BM-MNCs, but not PB-MNCs, reversed remodeling and reduced collagen density. Vessel counts showed greater angiogenesis occurred in the animals transplanted with BM-MNCs. Furthermore, a vascular endothelial cell-specific marker was detected in the transplanted bone marrow cells. Our data suggest that BM-MNC transplantation results in long-term improvement in left ventricular function-especially diastolic function- and remodeling, possibly related with the reduction of the amount of the collagen and enhancement of neovascularization.