Effect of brain traumatic tissue extract on the survival and differentiation of neural stem cells

Objective To simulate the chemical microenvironment after traumatic brain injury (TBI) and to investigate the effect of this microenvironment on the survival and differentiation of neural stem cells (NSCs). Methods The brain tissue homogenate of TBI rat model was harvested to simulate the chemical microenvironment after TBI. The primary NSCs of rat model were isolated and extraction, and then identified the phenotype characteristics with immunofluorescence staining. The experiments were divided into control group, normal brain tissue extract group (BTE group) and traumatic brain injury tissue extract group (TBITE group). The cell growth and morphological changes of each group were observed dynamically. The expression of apoptosis related protein, which includes Bax, Bcl-2, caspase-3 and cleaved caspase-3, were detected by Western Blot 24 h after experiments. The proliferation of NSCs was detected by MTT assay and Western Blot after 3 days. The differentiation level of NSCs to neurons was detected by immunofluorescence staining after 7 days. Results The results of Western Blot showed that compared with the control group, there was no significant change of apoptosis in the BTE group, while the apoptosis in the BTE group was significantly increased, showed a increase of expression levels of Bax (F=18.06, P<0.01) and Cleaved caspase-3 (F=23.86, P<0.01), and a decrease of that of Bcl-2 (F=22.95, P<0.01). The results of MTT assay showed that compared with the BTE group, the proliferation of NSCs in the TBITE group was decreased (F=41.99, P<0.01). The immunofluorescence staining showed that compared with the control group, the neuronal differentiation rate was increased in the BTE group. Further, compared with the BTE group, the neuronal differentiation rate in the TBITE group was decreased (F=66.93, P<0.01). Conclusion The injury microenvironment after TBI can significantly inhibit the survival and differentiation of NSCs, which provides a theoretical basis for clarifying the mechanism of endogenous nerve regeneration after TBI. Key words: Traumatic brain injury; Chemical microenvironment; Neural stem cells; Brain tissue extract