Brain-Derived Neurotrophic Factor Over-expressing Neural Stem Cells Promote Neuronal Survival And Cytoskeletal Protein Expression In TBI

Objective:Traumatic brain injury(TBI)is the brain injuries resulted from trauma,accordingly causing the neurons loss or death,leading to loss of related neurological function and even death of the neurons.With the developments of medicine at present,some progress has been made in the treatment of brain injury.However,the treatment and recovery of the related neurological function of the injured person are still a worldwide problem.Our previous study showed that transplantation of over-expressing brain-derived neurotrophic factor(BDNF)modified neural stem cells(NSCs)promoted the motor function of injured rats and the survival of injured peripheral nerve cells.This study further explores the underlying mechanisms of BDNF over-expressing neural stem cells(BDNF/NSCs)promoting the survival of injured areas and peripheral nerve cells and the mechanism of BDNF/NSCs transplantation promoting the recovery of motor function in rats,accordingly providing a theoretical basis for the treatment of TBI and recovery of nerve function.Methods:The stable BDNF/NSCs and NSCs obtained previously by our research group were subcultured,and then transplanted in the modified Feeney TBI model,respectively.Two groups were randomly assigned 72 hours after modeling:NSCs group and BDNF/NSCs group,the cell suspension of BDNF/NSCs and NSCs(2×10~7 cells/mL)were injected into in damage area,respectively,Then we extracted the transplanted areas and their surrounding areas in the first week,the second week,the third week and the fourth week after transplantion for relevant experimental study,respectively.In addition,we also performed PHK26 fluorescent labeling on the transplanted neural stem cells,and detected the proteins related to the skeleton,thesynapses and the oxidative stress regulation by immunohistochemistry,immunofluorescence and Western blotting.Results:We found that the levels of related proteins in the transplanted BDNF/NSCs group all significantly increased at all the time points after transplantation compared with the transplanted NSCs group.Definitely,In the transplanted BDNF/NSCs group,the proteins related to the skeleton(NF200,MAP2,Actin,CaM)were significantly increased,the expression of PSD-95 were significantly increased and the NF-kappaB,Trk B,Ras,p-Erk1/2,Nrf2and Trx were also significantly increased at different time points.Conclusion:This study was successfully constructed the Traumatic brain injury(TBI)model by transplanted BDNF/NSCs and NSCs to the corresponding BDNF/NSCs and NSCs group.Sequentially,We verified that the transplantion of BDNF-modified stem cells had been implicated in the promotion of the survival,growth and differentiation of injured stem cells,and the promotion of that were associated with the skeleton-related proteins.Furthermore,the promotion of BDNF on the expression of skeleton-related proteins and may be associated with the Wnt/?-catenin signaling pathway.In addition,we further studied the mechanism of BDNF promoting neurological function recovery after injury.The results showed that BDNF acted on the downstream Ras-Erk1/2 proteins through the BDNF/TrkB pathway,activating the anti-oxidative stress pathway Nrf2 and promoting the expression of Trx gene,thereby inhibiting oxidative stress,regulating the expression of synapsin,maintaining the synaptic plasticity between neurons,and promoting the recovery of related neurological functions.