Overexpression of β-NGF promotes differentiation of bone marrow mesenchymal stem cells into neurons through regulation of AKT and MAPK pathway

Bone marrow stromal stem cells (BMSCs) are fibroblastic in shape and capable of self-renewal and have the potential for multi-directional differentiation. Nerve growth factor (NGF), a homodimeric polypeptide, plays an important role in the nervous system by supporting the survival and growth of neural cells, regulating cell growth, promoting differentiation into neuron, and neuron migration. Adenoviral vectors are DNA viruses that contain 36 kb of double-stranded DNA allowing for transmission of the genes to the host nucleus but not inserting them into the host chromosome. The present study aimed to investigate the induction efficiency and differentiation of neural cells from BMSCs by beta-NGF gene transfection with recombinant adenoviral vector (Ad-beta-NGF) in vitro. The results of immunochemical assay confirmed the induced cells as neuron cells. Moreover, flow cytometric analysis, Annexin-V-FITC/PI, and BrdU assay revealed that chemical inducer beta-mercaptoethanol (beta-met) triggered apoptosis of BMSCs, as evidenced by inhibition of DNA fragmentation, nuclear condensation, translocation of phospholipid phosphatidylserine, and activation of caspase-3. Furthermore, the results of western blotting showed that beta-met suppressed AKT signaling pathway and regulated the MAPKs during differentiation of BMSCs. In contrast, Ad-beta-NGF effectively induced the differentiation of BMSCs without causing any cytopathic phenomenon and apoptotic cell death. Moreover, Ad-beta-NGF recovered the expression level of phosphorylated AKT and MAPKs in cells exposed to chemical reagents. Taken together, these results suggest that beta-NGF gene transfection promotes the differentiation of BMSCs into neurons through regulation of AKT and MAPKs signaling pathways.