无动物源性成分培养体系快速诱导人胚胎干细胞向视网膜色素上皮细胞的分化

Rapid differentiation of human ESCs into RPE cells by defined xeno-free culture system

背景 随着视网膜色素上皮（RPE）细胞视网膜下腔移植治疗年龄相关性黄斑变性（AMD）研究的开展,需要优化无动物源性成分（xeno-free）培养体系快速定向诱导人胚胎干细胞（hESCs）向RPE细胞分化以满足日渐增长的科研及临床需要. 目的 建立xeno-free培养体系,优化快速诱导hESCs向RPE细胞分化的方法. 方法 将hESCs克隆团接种至Vitronectin XFTM,在培养液中加入50 ng/ml noggin、10 ng/ml DKK-1以及10 ng/ml胰岛素样生长因子-1（IGF-1）培养2d,第2～4天将培养液中noggin质量浓度减至10 ng/ml,并加入5 ng/ml碱性成纤维细胞生长因子（bFGF）,第4～6天移除培养液中的noggin和bFGF,第8～14天培养液中加入1 μmol/L CHIR99021.倒置显微镜下观察ESCs在分化为RPE细胞过程中的形态变化,免疫荧光染色检测细胞内特异性抗原的表达以对分化细胞进行鉴定,实时荧光定量PCR （qRT-PCR）法检测细胞分化过程中RPE细胞特异性蛋白mRNA的相对表达变化量.结果 分化培养第14天,部分细胞呈多角形并呈现铺路石样排列,且细胞内可见色素颗粒;培养第35天,诱导分化的细胞内表达RPE细胞特异性抗原Mitf及RPE65;培养至第60天,细胞内富含黑色素颗粒且呈规则六边形.与诱导分化前比较,诱导分化第7天和第14天hES-RPE细胞中Mitf mRNA的表达量分别增加了（3.43±2.77）倍和（8.91±2.83）倍,而RPE65 mRNA的表达量分别增加了（14.60±3.94）倍和（87.16±9.32）倍,分化第7天和第14天细胞中的Mitf mRNA和RPE65mRNA的相对表达量均明显高于分化前,差异均有统计学意义（均P＜0.05）. 结论 hESCs可在含尼克酰胺、DKK-1、noggin、IGF-1和CHIR99021的xeno-free优化培养体系中快速分化为RPE细胞.

Background Subretinal transplantation of retinal pigment epithelium （RPE） cells for the treatment of age-related macular degeneration （AMD） have accelerated the drive to develop xeno-free cultivation system that support the rapid differentiation of human embryonic stem cells （hESCs） into ES-RPE cells.Objective This study was to report a modified xeno-free culture system and method for accelerating derivation of hESCs to differentiate into RPE cells.Methods This study was approved by Ethic Committee of Zhongshan Ophthalmic Center.HESC H1 line was cloned and cuhured in Vitronectin XFTM-coated 6-well dish with xenogenetic-free medium.Cells were cultured in 50 ng/ml noggin,10 ng/ml DKK-1 and 10 ng/ml insulin like growth factor-1 （IGF-1） medium for 2 days,and then the concentration of noggin was decreased to 10 ng/ml and 5 ng/ml basic fibroblast growth factor （bFGF） and cultured for the following 2 days.Sequentially,noggin and bFGF were removed and cultured for 2 days.Finally,1 μmol/L CHIR99021 was added in medium for 6 days.Morphological changes in the progress of ESCs differentiation into RPE were observed by Living Cell Imaging System.The expression of Mitf and RPE65,RPE cellsspecific markers,in the cells were detected by immunofluorescence technique,and the relative expression levels of RPE cells-specific marker mRNA were assayed using real time fluorescent quantitation PCR.Results Polygonalshape monolayer cells which contained pigments were initially observed at day 14 after cultured with the cobblestonelike arrangement.Mitf and RPE65 were strongly expressed in the hES-derived RPE cells 35 days after induced,showing red fluorescence,and the cells presented hexagonal shape at cultured day 60 with numerous pigment granules in cytoplasm.Compared with before differentiation,the expression levels of Mitf mRNA in hES-RPE cells increased by （3.43±2.77） folds and （8.91 ± 2.83） folds,and the expression levels of RPE65 mRNA increased by （14.60 ± 3.94） folds and （87.16 ±9.32） folds at day 7 and day 14 after differentiation,respectively （all at P〈0.05）.Conclusions A defined xeno-free culture system is successfully established by adding niacinamide,DKK-l,noggin,IGF-1 and CHIR99021 in xeno-free medium,and this system can accelerate the derivation and differentiation of hESCs into RPE-like cells.