Role of Thymosin β 4 on Skeletal Myoblast Migration, Proliferation, and Survival

Massive cell death associated with poor donor cell survival was a limiting factor in the success of myoblast transfer therapy (MTT). The current study is aimed to determine the effects of thymosin &β 4 on human skeletal myoblast (hSkM) migration, proliferation and survival under hypoxia. hSkM was cultured in basal medium (BM, M199 medium with 10% fetal bovine serum) supplemented with various concentrations of thymosin &β 4. Supernatant was collected to test the toxicity of thymosin &β 4 towards hSkM. Cell number was quantified using CyQuant cell proliferation assay kit. Cell viability was determined by calculating the lactate dehydrogenase (LDH) in the supernatant. hSkM migration was determined using cell culture insert. No significant toxicity of thymosin &β 4 towards hSkM was found when thymosin &β 4 was increased up to 600ng/ml. Thymosin &β increased hSkM proliferation rate by 35.4+13.4% at 600ng/ml. It enhanced hSkM viability (cell injury =10.9±1.7%) as compared with control (cell injury = 24.6%, p < 0.05) under hypoxia (5% CO2+ 94% N2+1% O2) for 48 hours (hrs). Increased migration rate (164.5+15/well, p<0.05 vs control) was achieved with thymosin &β 4 at 100ng/ml concentration. Thymosin &β 4 increased the activities of PI3K and AKT, and reduced the activities of caspases 3 and 8. We conclude that thymosin &β 4 increased hSkM migration and proliferation. It enhanced hSkM viability under hypoxia, providing a new strategy to improve hSkM survival in MTT. Furthermore, recent patents on thymosin &β 4 and skeletal myoblasts as therapeutic agents will be discussed.