不同胎龄大鼠神经干细胞体外诱导向多巴胺能神经元分化的比较

背景:胚胎来源干细胞的分化潜能不仅受到诱导条件影响,也受来源胚胎胚龄的影响.目的:实验拟观察不同胎龄大鼠中脑神经干细胞体外诱导向多巴胺能神经元分化能力.设计:随机对照观察.单位:中山大学附属第一医院神经外科.材料:实验于2007-03/2007-09在中山大学附属第一医院实验室完成.成年孕SD大鼠30只,体质量350～400 g,由中山大学动物实验中心提供.许可证号码为SCXK(粤)2007-0034.实验过程中对动物处置符合动温桌硌П曜?DMEM/F12无血清培养液、B27添加剂、表皮生长因子、碱性成纤维细胞生长因子、体积分数为0.1的胎牛血清为英国Gibco公司产晶;白细胞介素1α,白细胞介素11、胶质细胞源性神经营养因子购自美国R&D公司:白血病抑制因子购自英国PEPROTECH公司:酪氨酸羟化酶抗体购自美国Santa Cruz公司;巢蛋白抗体、微管相关蛋白2抗体及胶质纤维酸性蛋白抗体为美国CHEMICON公司产品.方法:①分别于大鼠孕10,12,14,16,18天摸球法随机选取6只,麻醉后处死孕鼠,无菌条件下剖腹取胚胎,分离中脑腹侧脑组织进行神经干细胞培养.在含表皮生长因子及碱性成纤维细胞生长因子的无血清培养液中分别培养不同胎龄大鼠脑神经干细胞,经传代扩增后,在含白细胞介素1α、白细胞介素11、白血病抑制因子、胶质细胞源性神经营养因子的诱导分化液中向多巴胺能神经元分化.②诱导分化6 d后观察分化细胞生长情况并进行免疫细胞化学鉴定:酪氨酸羟化酶染色标记后通过流式细胞仪检测分化的多巴胺能神经元比率.主要观察指标:①不同胎龄大鼠神经干细胞诱导分化后生长情况及免疫细胞化学鉴定结果.②神经干细胞诱导分化后酪氨酸羟化酶染色阳性细胞的比率.结果:①孕10,12,14,16,18 d胚胎大鼠中脑神经干细胞球在诱导分化液中贴壁生长,球内细胞从球体中央逐渐向外呈放射状生长,分化6天的细胞多数有1～2个长突起或有多个短突起.神经球经巢蛋白免疫细胞化学染色,大部分细胞胞浆染色呈阳性.②孕10,12,14,16,18 d胚胎大鼠中脑神经干细胞在诱导分化液中培养6 d后.流式细胞仪检测其诱导分化成酪氨酸羟化酶阳性细胞的比率分别为(10.3±2.5)%,(21.6±3.4)%,(16.7±2.8)%,(14.2±3.2)%,(8.9±1.8)%,各组间比较差异均有显著性意义(P<0.05),其中孕12 d大鼠中脑神经干细胞诱导分化成多巴胺能神经元比例最高.结论:不同胎龄大鼠中脑的神经干细胞体外诱导向多巴胺能神经元分化的能力不同,以孕12 d诱导分化成多巴胺能神经元比例最高.

Dopaminergic neuronal differentiation of neural stem cells in rats at different gestational ages

BACKGROUND: Differentiation inducing factors and gestational age influence the differentiation potential of embryonic neuralstem cells.OBJECTIVE: This study was designed to observe the differentiation potential of rat mesencephalic neural stem cells at differentgestational ages towards dopaminergic neurons.DESIGN: A randomized controlled observation.SETTING: Department of Neurosurgery, First Affiliated Hospital of Sun Yat-sen University, Guangzhou City, GuangdongProvince, China.MATERIALS: This study was performed at the Laboratory of the First Affiliated Hospital of Sun Yat-sen University between Marchand September 2007. Thirty adult gestational SD rats, weighing 350 400 g, were provided by the Laboratory Animal Center of SunYat-sen University (Permission No. 2007-0034). The protocol was performed in accordance with ethical guidelines stated in Guide forthe use and care of laboratory animals, approved by the Committee on the Care and Use of Laboratory Animals of the Institute ofLaboratory Animal Resources Commission on Life Sciences, National Research Council, China (1985). DMEM/F12 serum-free medium,B27 additives, epidermal growth factor, basic fibmblast growth factor, and fetal bovine serum (volume fraction:0, 1) were purchased fromGibco Company, British; Interleukin lα, interleukin 11, and glial cell-derived neurotrophic factors were purchased from R&D Company,USA; In addition, leukaemia inhibitory factor (Perpotech, British), tyrosine hydroxylase(Santa Cruz, USA), nidogen antibody,microtubule-associated protein 2 antibody, and glial fibrillary acidic protein antibody(Chemicon, USA) were also used.METHODS: Six rats were randomly selected at each time point (on days 10,12,14,16, and 18 after gestation). After anesthesia, therats were sacrificed. Under the aseptic condition, fetal rat was harvested. Rat mesencephalic ventral brain tissue was isolated forculture of neural stem cells. Different gestational ages of rat brain-derived neural stem cells were separately cultured in theserum-free medium containing epidermal growth factors and basic fibroblast growth factors. After passage and amplification, theneural stem cells were induced to differentiate towards dopaminergic neurons in the medium containing interleukin lu, interleukin11, leukaemia inhibitory factors, glial cell-derived leukaemia inhibitory factors. On day 6 after induction and differentiation, thedopaminergic neurons were observed and identified by immunocytochemistry. After labeled by tyrosine hydroxylase, thedifferentiated dopaminergic neuron proportion was detected by a flow cytometer.MAIN OUTCOME MEASURES: The growth state of differentiated rat neural stem cells at different gestational ages and theimmunocytochemistry results. The tyrosine hydroxylase staining-positive neural stem cell proportion after induction anddifferentiation.RESULTS: Rat mesencephalic neural stem cell spheres on days 10,12, 14, 16, and 18 after gestation adhesively grew in thedifferentiation-inducing medium. The neural stem cells in the spheres gradually grew in radial tendency. On day 6 afterdifferentiation, most of the neural stem cells exhibited 1-2 long processes or several short processes. After nidogenimmunocytochemical staining, most of neural stem cells exhibited cytoplasm-positive. After culture for 6 days in the differentiationinducing medium, rat mesencephalic neural stem cells at gestational 10,12, 14, 16, and 18 days were detected by a flow cytometer.Results demonstrated that the proportion of tyrosine hydroxylase-positive cells was (10.3±2.5)%, (21.6±3.4)%, (16.7±2.8)%,(14.2±3.2)%, and (8.9±1.8)%, respectively. There was a significant difference in the proportion of tyrosine hydroxylase-positivecells among the cells at different gestational days (P < 0.05). Rat neural stem cells at gestational 12 days could be induced todifferentiate into dopaminergic neurons at the highest proportion.CONCLUSION: Mesencephalic neural stem cells of rats at different gestational days have different capabilities to differentiatetowards dopaminergic neurons. The proportion of dopaminergic neurons is the highest when mesencephalic neural stem cells ofrats at gestational 12 days.