Thymosin ß4-Enhancing Therapeutic Efficacy of Human Adipose-Derived Stem Cells in Mouse Ischemic Hindlimb Model.

ABSTRACT

Thymosin ß4 (Tß4) 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 Tß4 and human adipose-derived stem cells (hASCs) in a mouse ischemic hindlimb model were investigated. We observed that exogenous treatment with Tß4 enhanced endogenous TMSB4X mRNA expression and promoted morphological changes (increased cell length) in hASCs. Interestingly, Tß4 induced the active state of hASCs by up-regulating intracellular signaling pathways including the PI3K/AKT/mTOR and MAPK/ERK pathways. Treatment with Tß4 significantly increased cell migration and sprouting from microbeads. Moreover, additional treatment with Tß4 promoted the endothelial differentiation potential of hASCs by up-regulating various angiogenic genes. To evaluate the in vivo effects of the Tß4-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 Tß4 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 Tß4 could be effective in enhancing endothelial differentiation and vascularization for treating hindlimb ischemia.