Thymosin beta 4-Enhancing Therapeutic Efficacy of Human Adipose-Derived Stem Cells in Mouse Ischemic Hindlimb Model

Abstract

Thymosin beta 4 (T beta 4) is a G-actin sequestering protein that contributes to diverse cellular activities, such as migration and angiogenesis. In this study, the beneficial effects of combined cell therapy with T beta 4 and human adipose-derived stem cells (hASCs) in a mouse ischemic hindlimb model were investigated. We observed that exogenous treatment with T beta 4 enhanced endogenous TMSB4X mRNA expression and promoted morphological changes (increased cell length) in hASCs. Interestingly, T beta 4 induced the active state of hASCs by up-regulating intracellular signaling pathways including the PI3K/AKT/mTOR and MAPK/ERK pathways. Treatment with T beta 4 significantly increased cell migration and sprouting from microbeads. Moreover, additional treatment with T beta 4 promoted the endothelial differentiation potential of hASCs by up-regulating various angiogenic genes. To evaluate the in vivo effects of the T beta 4-hASCs combination on vessel recruitment, dorsal window chambers were transplanted, and the co-treated mice were found to have a significantly increased number of microvessel branches. Transplantation of hASCs in combination with T beta 4 was found to improve blood flow and attenuate limb or foot loss post-ischemia compared to transplantation with hASCs alone. Taken together, the therapeutic application of hASCs combined with T beta 4 could be effective in enhancing endothelial differentiation and vascularization for treating hindlimb ischemia.