EFFECT OF Akt1 GENE TRANSFECTION ON HYPOXIA TOLERANCE OF BONE MARROW MESENCHYMAL STEM CELLS

OBJECTIVE: To investigate whether Akt1 gene transfection mediated by recombinant lentivirus (LVs) in the bone marrow mesenchymal stem cells (BMSCs) could enhance the ability of hypoxia tolerance so as to provide a theoretical basis for improving the effectiveness of stem cells transplantation. METHODS: LVs was used as transfection vector, enhanced green fluorescent protein (EGFP) was used as markers to construct the pLVX-EGFP-3FLAG virus vector carrying the Akt1 gene. The 3rd generation BMSCs from 3-5 weeks old Sprague Dawley rats were transfected with pLVX-EGFP virus solution as group B and with pLVX-EGFP-3PLAG virus solution as group C; and untransfected BMSCs served as control group (group A). At 2-3 days after transfection, the expression of green fluorescent was observed by fluorescence microscope; and at 48 hours after transfection, Western blot method was used to detect the expression of Akt1 protein in groups B and C. BMSCs of groups B and C were given hypoxia intervention with 94% N₂, 1% O₂, and 5% CO₂ for 0, 3, 6, 9, and 12 hours (group B1 and group C1). The flow cytometry was used to analyze the cell apoptosis rate and cell death rate, and the MTT method to analyze the cell proliferation, and Western blot to detect the expression of apoptosis related gene Caspase-3. RESULTS: After transfection, obvious green fluorescence was observed in BMSCs under fluorescence microscopy in groups B and C, the transfection efficiency was about 60%. Akt1 expression of group C was significantly higher than that of group B (t = 17.525, P = 0.013). The apoptosis rate and cell death rate of group B1 increased gradually with time, and difference was significant (P < 0.05). In group C1, the apoptosis rate and cell death rate decreased temporarily at 3 hours after hypoxia intervention, then increased gradually, and difference was significant (P < 0.05). The apoptosis rate and cell death rate of group C1 were significantly lower than those of group B1 at each time point (P < 0.05) except at 0 hour. MTT assay showed tat absorbance (A) values of groups B and C were significantly higher than those of groups B1 and C1 at each time point (P < 0.05); the A value of group B was significantly lower than that of group C at each time point (P < 0.05). The A value of group B1 was significantly lower than that of group Cl at 6, 9, and 12 hours after hypoxia intervention (P < 0.05). Western blot results showed that the Caspase-3 expression of group C1 significantly reduced when compared with group B1 at each time point (P < 0.05). CONCLUSION: Akt1 gene transfection mediated by recombinant LVs could significantly improve hypoxia tolerance of BMSCs by inhibiting the apoptosis, which could provide new ideas for improving the effectiveness of stem cells transplantation.