RESUMEN
Objective To observe the effects of mesenchymal stem cells (BMSCs) on the expression of Bcl2 and Bax in atrophied muscles.Methods Immature rats (80～ 100 g) were anesthetized to collect marrow from their femurs and tibias.BMSCs were isolated from the marrow,cultured and purified using the whole bone marrow adherence method.Their right hindlimbs were immobilized fiom the thigh to the paw with the knee in extension and the ankle in plantar flexion.After the modeling,24 of the male rats were divided into a sham-operation group,a BMSC group and a phosphate buffer solution (PBS) group,each of 8.The BMSC and PBS groups were injected with either approximately 106 BMSCs or an equal volume of PBS into the belly of the soleus muscle after they had been immobilized for 48 hours,while the control group did not undergo any treatment except for the injection of PBS.All of the rats were sacrificed for analysis after 14 days.Results The BMSCs were mainly spindle cells,showing radial colony arrangement.They grew vigorously and could passage in a continuous and stable manner over 10 passages.At the 4th passage the BMSCs were positive for CD44 (95.84％) and CD90 (96.00％),but negative for CD34 and CD45.Western blotting assay demonstrated that the expression of Bax protein as measured in grey-scale value (0.41±0.08)in the BMSC group was significantly lower than in the PBS group (0.63±0.10),but significantly higher than in the control group (0.14±0.11) on average.The expression of Bcl-2 (0.47±0.14) was also significantly higher in the BMSC group than in the PBS group (0.22-± 0.13),but significantly lower than in the control group (0.81 ± 0.06).Conclusion Bone marrow mesenchymal stem cells can upregulate the expression of anti-apoptotic Bcl-2 protein and downregulate that of the apoptotic Bax protein when injected early into the belly of a muscle in an immobilized limb.