Abstract 1448: Transplantation of Microspheres and Fibroblasts after Myocardial Infarction Improves Left Ventricular Function in a Rat Model Based on Inflammatory Processes
Myocardial infarction followed by congestive heart failure is still prevalent in developed countries. As a novel and promising therapeutic strategy for heart failure application of different cell types is the subject of increasing research interest. In this study we investigated the effect of several transplanted cell types and microspheres (uniform polystyrene microspheres, 10 μm diameter) on myocardial function after myocardial infarction. Human fibroblasts (1 x 106, n=8), macrophages (1 x 106, n=8), microspheres (1 x 106, n=8) and medium (n=10) were injected directly into border zones of infarcted myocardium of rats, that had undergone ligation of the left anterior descending artery 4 weeks before. Eight weeks after transplantation isolated heart studies (Langendorff) revealed a significant improvement of left ventricular function after injection of fibroblasts and microspheres (LVDP fibroblasts: 129 ± 32,86 mmHg, LVDP microspheres: 119,2 ± 24,1 mmHg) in contrast to injection of macrophages or medium alone (LVDP medium: 67 ± 22,6 mmHg, LVDP macrophages: 75,9 ± 24,8 mmHg, p<0,05). Rare BrdU positive signals could be detected in infarcted areas after transplantation of fibroblasts. Microspheres could be detected with high frequency by autofluorescence. There were no detectable signals after transplantation of macrophages. Further histologic results showed significantly more apoptotic cells in infarcted areas in macrophage (328,6 ± 37,4 cells/mm2) and medium (338,7 ± 16,52 cells/mm2; p<0,05)-treated hearts in contrast to microsphere (233,2 ± 16,82 cells/mm2) and fibrobast (232,2 ± 19,14 cells/mm2)- injected hearts. The density of CD 31 positive vessels did not differ between the 4 groups studied. These results demonstrate, that neovascularisation is not a prerequisite to improved cardiac function after cell based therapy. The significantly increased number of macrophages in infarcted areas after fibroblast and microsphere injection (fibroblasts: 94,72 ± 7,08 cells/mm2, microspheres: 82,22 ± 3,02 cells/mm2, macrophages: 56,02 ± 9,93 cells/mm2, medium: 46,35 ± 9,03 cells/mm2, p<0,05) suggests that the underlying mechanism of augmented left ventricular function might be based on inflammatory processes.