Abstract
In this study, we investigated age-related effects on muscle progenitor cells (MPCs) with respect to cell growth, recombinant protein expression, and engineered muscle histology and contractility. An in vitro analysis included: examining cell growth through a proliferation assay and recombinant protein expression. In addition, we genetically modified the cells to express Vascular Endothelial Growth Factor (VEGF) to stimulate neovascularization. After expansion of the MPCs, 5x106 cells were mixed with collagen and were injected subcutaneously into mice. After 2, 4, and 6 weeks, the engineered muscle samples were harvested, analyzed by immunohistochemistry, by organ bath studies, and by VEGF western blot. Cell expansion was successfully performed with MPCs derived from animals in all 3 age groups. It was evident that the growth rate of cells from younger mice was greater than that of mature mice, which was also greater than older mice. However, MPCs from all three age groups showed equal DNA transfection and infection efficiency. The in vivo study demonstrated that it is possible to create functional muscle tissues from MPCs of all ages. However engineered muscles from older mice showed decreased muscle formation, volume and function. Recombinant VEGF expression induced neovascularization and increased muscle volumes. This study demonstrates an apparent age-related decline in the ability of MPCs to create an engineered muscle tissue in vivo. However, it is possible to engineer muscle tissues with MPCs derived from all mouse ages. Finally, augmentation of neovascularization can increase muscle mass and strength of contractility of engineered muscle tissues.
Published Version
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