人脐血间充质干细胞治疗鼠创伤性脑损伤后BDNF的变化

Changes of BDNF after treatment of traumatic brain injury with human umbilical cord blood mesenchymal stem cells in rats

目的探讨人脐血间充质干细胞(HUCBMSCs)治疗鼠创伤性脑损伤的可能机制。方法将SD大鼠随机分为假伤组、对照组和治疗组,每组30只。体外培养HUCBMSCs,用5-溴脱氧尿核苷(Brdu)标记。制备创伤性脑损伤(TBI)模型,治疗组注入标记的HUCBMSCs。对照组和治疗组进行神经损伤严重程度评分(NSS),免疫组化法测定各组大鼠Brdu及脑源性神经营养因子(BDNF)蛋白的表达,原位杂交法测定BDNF mRNA的表达。结果①假伤组和对照组未见Brdu阳性细胞。治疗组见Brdu标记阳性细胞,且随时间延长Brdu标记细胞减少;②注射后7 d起,治疗组神经功能评分较损伤组改善;③假伤组有少量BDNF蛋白及mRNA阳性细胞。对照组和治疗组BDNF蛋白及mRNA表达升高,注射后14 d达高峰,之后逐渐下降,但高于假伤组。治疗组BDNF蛋白及mRNA阳性细胞表达高于相同时间点对照组。结论未用免疫抑制剂条件下,HUCBMSCs在大鼠脑内至少存活4周;经尾静脉注射的HUCBMSCs迁移至脑创伤灶周边区;注入HUCBMSCs后,神经损伤程度改善,BDNF蛋白及mR-NA表达增多,有利于损伤脑组织的修复。

Objective To study the potential mechanism for treatment of traumatic brain injury with human umbilical cord blood mesenchymal stem cells （HUCBMSCs） in rats. Methods HUCBMSCs were cultured in vitro and labled with 5-bromo-2-deoxyuridine（Brdu）. Sprague-Dawley（SD） rats which suffered from traumatic brain injuries were ran- domly divided into 3 groups （30 rats in each group） ： sham-operated group, control group and treatment group which was injected intravenously with the labled HUCBMSCs. The neurological severity score（NSS） were evaluated in con- trol group and treatment group. Additionally, brain-derived neurotrophic factor （BDNF） was determined at protein lev- el by immunohistochemistry and at mRNA level by in situ hybridization. Results ①There was no Brdu-labeled cells in sham-operated group and control group. However, Brdu-labeled cells gathered obviously in the damage surrounding are- a in treatment group and the labeled cells decreased gradually with the time prolonged; ②NSS was obviously improved in treatment group since day 7 after the adminstration of HUCBMSCs; ③There were only a minimal number of nervecells expressing BDNF in the sham-operated group. Both of control and treatment group showed remarkable increases of BDNF expression which reached a peak at day 14 after injection of HUCBMSCs and then declined gradually. However, BDNF expression increased significantly in treatment group, compared with control group at same time points. Contu- sion HUCBMSCs can survive for at least 4 weeks in brain tissues without application of immunosuppressants in rats. The intravenously injected HUCBMSCs which distribute in the damage surrounding area are more than in other areas. The current study indicates that the brain demage is improved after HUCBMSCs injection and the enhanced BDNF ex- pression benefits in the repair of demaged brain tissues.