体外无血清培养基条件下诱导人骨髓基质细胞为神经干细胞的特征

背景:体外诱导骨髓基质细胞向神经元样细胞分化的方法主要是应用抗氧化剂如β-巯基乙醇、全反式维甲酸、丹参等,这些诱导方法分化的主要是神经元样细胞,这种细胞是否具有神经元的功能有待进一步观察。目的:观察体外无血清培养基条件下人骨髓基质细胞向神经细胞分化的特点。设计:观察实验。单位:潮州市中心医院。材料:实验于2004-04/2005-12在潮州市中心医院完成。成人骨髓来源于3例骨折患者的股骨和胫骨骨髓,获得患者及其家属的同意及潮州市中心医院伦理委员会批准。重组人碱性成纤维细胞生长因子和重组人表皮生长因子为Sigma公司产品;鼠抗波形蛋白单克隆抗体、鼠抗S100单克隆抗体、鼠抗TrkC单克隆抗体、鼠抗髓鞘基础蛋白单克隆抗体、SP-9000试剂盒和即用型AEC为北京中山公司产品;鼠抗GFAP单克隆抗体、兔抗巢蛋白多克隆抗体、鼠抗神经元特异性烯醇化酶单克隆抗体和鼠抗神经微丝200单克隆抗体在武汉博士德公司购买;鼠抗βⅢ管蛋白单克隆抗体为Sigma公司产品。方法:在手术骨折内固定过程中获得成人骨髓,缓冲液冲洗后分离细胞,原代培养的细胞融合时传代培养,细胞种植在神经干细胞的N2培养基或B27培养基,同时加入20μg/L的碱性成纤维细胞生长因子及表皮生长因子,放入含体积分数0.05CO2的培养箱中37℃常规培养,相差显微镜下观察骨髓基质细胞在无血清培养基中的形态变化,培养2d后采用免疫细胞化学方法检测骨髓基质细胞的神经细胞相关标志物的表达。主要观察指标:骨髓基质细胞的形态变化及神经细胞相关标志物的表达。结果:①从成年人的骨髓中分离出骨髓基质细胞,在体外生长形态类似成纤维细胞,可以维持在未分化状态稳定增殖,体外扩增可超过10代。骨髓基质细胞在无血清神经干细胞的培养基中生长状态类似神经干细胞,可以形成典型的球状结构。②细胞球可表达神经干细胞的标志物波形蛋白和巢蛋白;细胞分化可以表达神经元的标志物神经微丝200、神经元特异性烯醇化酶、TrkC和βⅢ管蛋白;部分分化的细胞表达胶质纤维酸性蛋白和S100,说明细胞分化为星形胶质细胞。结论:骨髓基质细胞在神经干细胞的无血清的培养基中细胞的生长状态、表达的标志物和分化的细胞类型与神经干细胞类似。

In vitro differentiation of human bone marrow stromal cells into neural stem cells in serum-free medium

BACKGROUND:At present,the most frequently agents used for neural induction of bone marrow stromal cells(BMSCs)in vitro are anti-oxidants,such as beta-mercaptoethanol and all trans-retinoids.The majorities of induction from BMSCs are neuron-like cells in these protocols;however,whether it has neuronal function or not should be further studied.OBJECTIVE:TO investigate the differentiated characteristics of inducing human BMSCs into neural cells in serum-free medium.DESIGN:Observational study.SETTING:Chaozhou Central Hospital.MATERIALS:The experiment was carried out in the Chaozhou Central Hospital from April 2004 to December 2005.Adult bone marrows were derived from femoral and tibial bone marrow of three patients with fracture.All patients provided the confirmed consent and were approved by the Ethics Committee of Chaozhou Central Hospital.DMEMIF12 medium(1:1),fetal bovine serum (FBS), glutamine, N2 supplements and B27 Supplements were from GIBCO/BRL Company;recombinant basic fibroblast growth factor(bFGF)and recombinant epidermal growth factor(EGF)from Sigma Company;monoclonal antibody for vimentin(1:100),monoclonal antibody for myelin basic protein(MBP) (1:100),monoclonal antibody for S1 00(1:1 00),monoclonal antibody for neuron specific enolase(NSE)(1:1 00),and monoclonal antibody for neurofilament 200(NF200)(1:1 00)from Beijing Zhongshan Company;monoclonal antibody for glial fibrillary acidic protein (GFAP)(1:200)and polyclonal antibody for nestin(1:100)from Boster Company(Wuhan);mouse monoclonal antibody for beta-tubulin 3(1:1 000)from Sigma Company;SP-9000 kits and quick AEC from Beijing Zhongshan Company; culture dishes and flasks from Coming Company.METHODS:BMSCs from human bone marrow were cultured in serum-containing medium.When the primary culture was established, BMSCs were transferred into serum-free medium containing N2 or B27 supplement with 20 μg/L basic fibroblast growth factor(bFGF)and epidermal growth factor(EGF),and cells were cultured in an incubator containing C02of 0.05 volume fraction at 37℃. Morphological changes of BMSCs in serum-free medium were observed under phase contrast microscope. And two days after culture. Expression of relative markers of BMSCs was detected withimmunocytochemistry.MAIN OUTCOME MEASURES:Morphological changes of BMSCs and expression of relative markers of nerve cells.RESULTS:A population of BMSCs could be isolated from adult human bone marrow,and they were processed to obtain a fibroblast-like population and were expanded as undifferentiated cells in culture for more than 10 passages.indicating their proliferative capacity.They could form spheroid state when they were sub-cultured in serum-free media supplemented with bFGF and EGF.these cells could express the markers for neural stem cells such as vimentin and nestin;they could expressed neuron specific enolase(NSE),beta-tubulin 3,TrkC and neurofilament 200(NF200)when they were plated on dishes with serum-containing medium; some cells exhibited the phenotypes for astrocytes.expressing gilal fibrillary acidic protein(GFAP)and S100 protein.CONCLUSION:The morphology,protein expression and differentiation ability of BMSCs in serum-free medium was similar to those of neural stem cells.The data support the hypothesis that adult bone marrow contains stem cells capable of differentiating into neural cells,the serum-free media make BMSCs overcome their mesenchymal commitment,showing the phenotypes for neural stem cells.