人胚胎干细胞来源的视网膜色素上皮细胞超微结构观察方法的优化

摘要

背景 视网膜色素上皮(RPE)细胞的正常超微结构是其执行正常生理功能的解剖基础,目前用透射电子显微镜(TEM)检测RPE细胞的超微结构时常用细胞沉淀法,但经过胰蛋白酶消化的细胞会破坏原有的细胞生长状态,无法真实地反映出体外培养的RPE细胞的超微结构. 目的 探索一种能够简单、真实地反映体外培养的入胚胎干细胞(hESC)来源的RPE细胞超微结构的方法. 方法 将hESC经自然分化法诱导为hESC来源的RPE(hESC-RPE)细胞,采用免疫荧光法检测hESC-RPE细胞特异性蛋白小眼畸形相关转录因子(MITF)和人类配对盒基因6(PAX6)的表达.将hESC-RPE细胞种植于Transwell小室上进行培养,待细胞形成细胞片后通过TEM进行超微结构的观察,并与细胞沉淀法制备的hESC-RPE细胞标本的超微结构和90日龄Long Evans大鼠体内RPE细胞的超微结构进行比较. 结果 hESC-RPE细胞MITF和PAX6表达阳性.TEM下可见大鼠体内RPE细胞正常的超微结构,包括顶端微绒毛、极性分布的RPE细胞色素颗粒和细胞核、细胞基底膜和细胞间紧密连接.细胞片法TEM下可见Transwell小室上细胞片中hESC-RPE细胞形成了类似于大鼠体内RPE细胞的超微结构,但细胞顶端微绒毛较短,而细胞沉淀法观察到hESC-RPE细胞的细胞质中散在分布的色素颗粒、非极性的细胞核和少量的微绒毛.结论 TEM观察细胞超微结构时细胞片法不经过细胞的消化过程,保留了hESC-RPE细胞的正常结构,能简单、真实地反映体外培养RPE细胞的超微结构.%Background Normal ultrastructure is the anatomical basis of retinal pigment epithelial(RPE) cells to perform normal physiological function.At present the precipitation method is often used to detect the ultrastructure of RPE cells with transmission electron microscopy(TEM).Objective The aim of this study was to explore a simple and feasible approach to examine the ultrastructure of human embryonic stem cell-derived retinal pigment epithelial (hESC-RPE) cells.Methods hESCs were induced and differentiated into RPE cells by the spontaneous differentiation method,and the expressions of microphthalmia associated transcription factor MITF and paired-box gene 6 (PAX6),specific protein of RPE cells,in the cells were detected by immunofluorescence assay.hESC-RPE cells were inoculated into Transwell filter,and the ultrastructure of the cell sheet was examined under the TEM.Then the ultrastructure of the cell sheet specimens was compared with those of hESC-RPE cells from cell precipitation and RPE cell specimens of 90-day-old Long Evans rats.Results MITF and PAX6 were positively expressed in hESC-RPE cells.The normal ultrastructure were visible in the RPE cells of rats under the TEM,including apical microvilli,polarized melanin granules,cellular nucleus,basement membrane and intercellular junctions,and the ultrastructure of hESC-RPE cell sheet on Transwell was similar to the RPE cells in rats.However,only scatter melanin granules,nonpolar nucleus and scanty microvilli were observed under the TEM in the hESC-RPE cells by cell precipitation method.Conclusions Without digestion process,hESC-RPE cell sheet on Transwell can retain the normal ultrastructure of hESC-RPE cells under the TEM,with a more simple and reliable advantage.