Intravenous injection of human umbilical cord blood mesenchymal stem cells affecting the level of nerve growth factors in rats with traumatic brain injury

Objective To investigate the effect of transplantation of human umbilical cord blood mesenchymal stem cells (CB-MSCs) on the levels of NGF and BDNF in rats with traumatic brain injury (TBI) and explore its possible mechanism of cerebral protection. Methods Ninety healthy male SD rats were equally randomized into sham-operated group, injury control group and treatment group.TBI models in the injury control group and treatment group were induced by the improved device of Feeney weight-dropping; the rats in the treatment group were injected Brdu-labeled 3×106 CB-MSCs solved in 1ml PBS by rat-tail vein, while the rats in the sham-operated group and the injury control group were injected the equal volume of PBS solution. No immunosuppressive agents were used in all the rats.HE staining, immunohistochemistry, in-situ hybridization were employed, respectively, to detect the morphological changes, Brdu positive cells, expressions of BDNF and NGF on the 3rd, 7th, 14th, 21st and 28th d of injection. Results Only a very small number of nerve cells were BDNF and/or NGF positive in the sham-operated group. Substantial BDNF and/or NGF positive cells in the injury control group were noted in the surrounding brain damaged area following traumatic brain injury, which peaked at their levels on about 14 d of injection (the A value of NGF=8.35±1.07, that of BDNF=9.01±1.74), following by a gradual decline; however, significant difference was still noted as compared with that in the sham-operated group (P＜0.05). BDNF and/or NGF-positive cells significantly increased in the treatment group, especially in the surrounding brain injured areas; their levels peaked on the 14th d of injection,following by a gradual decline on the 21st and 28th d, but they were still higher than those in the injury control group and sham-operated group at each time points (P＜0.05). Conclusion Transplantation of CB-MSCs can increase the secretion of BDNF and NGF in rats with TBI, improve the local micro-damage environment and promote the repair of neurons. Key words: Mesenchymal stem cell transplantation; Craniocerebral trauma; Nerve growth factor; Brain-derived neurotrophic factor