胶质细胞源性神经营养因子联合转化生长因子β1体外诱导大鼠脊髓源性神经干细胞的分化

背景:胶质细胞源性神经营养因子与转化生长因子β1同属于转化生长因子β超家族,两者在哺乳动物中枢与外周神经系统发育、分化及细胞周期的调节中扮演重要角色。目的:观察胶质细胞源性神经营养因子联合转化生长因子β1体外诱导脊髓源性神经干细胞的分化,并与单一因子诱导培养液比较。设计:对照观察。单位:南方医科大学附属深圳医院中心实验室。材料:选用10只清洁级孕16d的SD大鼠,由华中科大同济医学院动物中心提供。主要试剂及材料:DMEM/F12,B27(GIBCO);碱性成纤维细胞生长因子,EGF,胶质细胞源性神经营养因子,转化生长因子-β1(PeproTech);胎牛血清(Hyclone);神经巢蛋白(nestin)多抗(武汉博士德);胶质纤维酸性蛋白(GFAP)多抗,神经丝蛋白(NF-200)单抗(Sigma)。方法:实验于2005-10/2006-09在南方医科大学附属深圳医院中心实验室完成。无菌条件下分离大鼠胚胎,进行脊髓源性神经干细胞的分离培养。实验分①基础培养基组:含青霉素、链霉素、两性霉素B及体积分数为0.02 B27添加液的DMEM/F12。原代培养1周后,获取体外稳定增殖的鼠脊髓源性神经干细胞克隆。②对照组:在基础培养基中加入体积分数为0.1的胎牛血清。③碱性成纤维细胞生长因子组。④转化生长因子β1组。⑤胶质细胞源性神经营养因子 转化生长因子β1组。换用诱导培养基,即分别在基础培养基中加入20μg/L碱性成纤维细胞生长因子、2μg/L转化生长因子β1、10μg/L胶质细胞源性神经营养因子 2μg/L转化生长因子β1。①光镜观察在不同因子诱导情况下脊髓源性神经干细胞的分化情况。②免疫细胞化学染色标记检测神经元与星状胶质细胞的表达。③通过荧光激发流式细胞仪分选技术对分化细胞计数,检测不同诱导环境下神经干细胞分化为神经元及星状胶质细胞的阳性百分率。主要观察指标:①各组细胞分化的形态学特点。②各组神经干细胞免疫组织化学检测结果。③各组神经干细胞分化为神经元及星状胶质细胞的阳性百分率。结果:①细胞分化形态:分化早期可见神经球贴壁,大量细胞向四周爬出,1周后迁徙的大部分细胞完全贴壁,完成分化过程。在细胞密度较低区域可辨认出神经元样细胞、星状胶质样细胞、寡突胶质样细胞。②免疫组织化学检测结果:对照组、转化生长因子β1组存在大量胶质纤维酸性蛋白染色阳性的星状胶质细胞;而碱性成纤维细胞生长因子组及胶质细胞源性神经营养因子 转化生长因子β1组分化的神经元细胞数量较多,神经丝蛋白染色阳性。③神经元及星状胶质细胞的阳性百分比:诱导1周后,胶质细胞源性神经营养因子 转化生长因子β1组神经元阳性百分比高于血清对照组、碱性成纤维细胞生长因子组及转化生长因子β1组(χ2=24.15,19.56,25.32,P<0.05～0.01),星状胶质细胞阳性百分比低于血清对照组及转化生长因子β1组(χ2=24.45,23.79,P<0.01)。结论:体外胶质细胞源性神经营养因子与转化生长因子β1的联合诱导有利于脊髓源性神经干细胞向神经元的分化,说明两者具有协同作用。

Glial cell-derived neurotrophic factors combined with transforming growth factor-beta 1 for in vitro differentiation of neural stem cells from rat spinal cord

BACKGROUND: Glial cell-derived neurotrophic factor (GDNF) and transforming growth factor-beta 1 (TGF-β1)co-subordinate to TGF-β family. Both of them play very important roles in the development and differentiation of central and peripheral nervous system, and regulation of cell cycle in mammals.OBJECTIVE: To observe the differentiation of spinal cord-derived neural stem cells(NSCs) induced by GDNF combined with TGF-β1, and make a comparison of differentiation results with GDNF or TGF-β1 culture fluid.DESIGN: Controlled observation.SETTING: Central Laboratory, Shenzhen Hospital Affiliated to Southern Medical University.MATERIALS: Ten SD rats of clean grade, which were at conception for 16 days, were provided by the Experimental Animal Center, Tongji Medical College, Huazhong University of Science and Technplogy. Main reagents and materials:DMEM/F12,B27(GIBCO); basic fibroblast growth factor (bFGF), GDNF; TGF-β1(PeproTech);fetal bovine serum (FBS,Hyclone); nestin multiple antibody (Boster, Wuhan); glial fibrillary acidic protein (GFAP) multiple antibody; neurofilament protein (NF-200) monoclonal antibody (Sigma).METHODS: This experiment was carried out in the Central Laboratory, Shenzhen Hospital Affiliated to Southern Medcial University between October 2005 and September 2006. Under the aseptic condition, rat fetus was isolated for isolation and culture of spinal cord-derived neural stem cells. In this study, five groups were divided: basal medium group, control group, bFGF group, TGF-β1 group, GDNF+ TGF-β1 group. In the basal medium group, DMEM/F12 containing penicillin,streptomycin, amphotericin (AMPH) B and 0.02 volume fraction of B27 annex solution. At 1 week after primary culture, rat spinal cord-derived NSC clones proliferated in vitro stably were harvested. In the control group, 0.1 volume fraction of FBS was added into basal medium. In the later three groups, induced medium was exchanged, i.e. 20 μg/L bFGF, 2 μg/L TGF-β1, and 10 μg/L GDNF+2 μg/L TGF-β1 were added into the basal medium, respectively. ①The differentiation of spinal cord-derived NSCs induced by different factors were observed under the optical microscope. ②The expressions of neurons and astrocytes were detected by immunocytochemical staining labeling. ③ The differentiated cells were counted by sorting technique by means of fluorescence excitation flow cytometer, and the percentage of NSCs differentiating into neurons and astrocytes were detected under the different induction environments.MAIN OUTCOME MEASURES: ① Morphological feature of cell differentiation in each group. ② Immunohistochemical detection of NSCs in each group. ③ The percentage of NSCs differentiating into neurons and astrocytes in each group.RESULTS: ① Cell morphology during differentiation: At the early stage of differentiation, lots of cells creeped to all the directions, and one week later, most of the migrated cells adhered to the wall entirely. Neuron-like cells, astrocyte-like cells and oligodendrocyte-like cells could be identified in the low-density cell region. ②Immunohistochemical detection results: A lot of GFAP- positive astrocytes were found in the control group and TGF-β1 group; Many differentiated neurons and NF-200 staining positive were found in the bFGF group and GDNF+ TGF-β1 group. ③Percentage of stained neuron and astrocyte: at one week of induction, the percentage of stained neurons was higher in the GDNF+ TGF-β1 group than in the control group, bFGF group and TGF-β1 group (x2=24.15,19.56,25.32,P ＜ 0.05-0.01), and the percentage of stained astrocytes was lower in the GDNF+ TGF-β1 group than in the control group, bFGF group and TGF-β1 group (x2=24.45,23.79,P ＜ 0.01 ).CONCLUSION: The combined in vitro induction of GDNF and TGF-β1 contributes to the neuronal differentiation of spinal cord-derived NSCs, indicating that both of them have synergistic effect.