人脂肪间充质干细胞向视网膜色素上皮样细胞的诱导分化及其在体应用研究

Study on human adipose mesenchymal stem cells differentiating into retinal pigment epithelial-like cells and its in vivo application

背景 目前,干细胞疗法治疗视网膜变性疾病是眼科研究的热点之一.研究已证实骨髓间充质干细胞（MSCs）可以体外诱导分化为视网膜色素上皮（RPE）样细胞,但由于取材困难,临床应用受到了一定的限制.人脂肪间充质干细胞（ADSCs）与MSCs有类似的特性且容易获取,但人ADSCs能够诱导分化为RPE细胞的研究尚不多见. 目的 评估人ADSCs向RPE样细胞诱导分化的可行性及其在体应用的安全性.方法 将体外培养的第3代人ADSCs接种于6孔板进行培养,12h后于实验组培养液中加入100 ng/ml表皮生长因子（EGF）、50 μmol/L牛磺酸和5×10-7 mol/L视黄酸进行诱导,常规培养的细胞作为对照组.采用RPE细胞标志物Pan细胞角蛋白（Pan-CK）单克隆抗体进行免疫荧光检测,对诱导的细胞进行鉴定,采用细胞膜示踪剂PKH26标记法示踪诱导细胞,将诱导后的RPE样细胞悬液lμl注入6只BALB/c裸鼠的右眼玻璃体腔,另6只裸鼠玻璃体内注射等容量PBS.于注射后1个月摘取实验动物右眼眼球,各组中3只眼球用于组织病理学检查,在光学显微镜下观察玻璃体视网膜的形态学改变,另3只眼球在透射电子显微镜下观察玻璃体视网膜超微结构的改变,评估诱导细胞在体应用的安全性. 结果 体外培养的第3代人ADSCs呈细长多角形,生长良好.对照组细胞Pan-CK表达缺失,而诱导细胞的细胞膜Pan-CK表达阳性,呈红色荧光.诱导的细胞经PKH26标记后细胞膜呈红色荧光.诱导的细胞悬液于裸鼠玻璃体内注射后1个月,光学显微镜下可见诱导细胞位于视网膜表面,视网膜各层组织结构排列清晰;透射电子显微镜下可见视网膜神经节细胞（RGCs）细胞膜完整,线粒体结构正常,染色质均匀. 结论 人ADSCs体外诱导后可分化为RPE样细胞,PKH26可对诱导后细胞进行细胞示踪,分化的细胞玻璃体腔注射后短期内未发现视网膜的不良反应。

Background Stem cell transplantation represents a promising treatment option for patients suffering from degenerative disorders.Accumulating evidences indicate that mesenchymal stem cells （MSCs） are able to differentiate into retinal pigment epithelial （RPE）-like cells.However,MSCs are difficult to obtain.Human adipose mesenchymal stem cells （ADSCs） are proved to have similar properties to MSCs,but relevant study is less.Objective This study was to assess the feasibility of human ADSCs differentiating into RPE-like cells and the safety of its application in vivo.Methods The third generation of human ADSCs were incubated into 6-well plate,and 100 ng/ml epithelial growth factor,50 μ mol/L taurine and 5×10-7 mol/L retinoic acid were added into the medium 12 hours after cultured to induce the cells,and conventional cultured cells were used as the control group.Induced cells were traced with PKH26,and Pan-cytoke ratin （Pan-CK） monoclonal antibody was used to identify the cells under the fluorescence microscope.Induced RPE-like cell suspension of 1 μl was intravetreally injected in the right eyes of 6 BALB/c mice,and equal volume of PBS was used in the same way in another 6 mice.The animals were sacrificed 1 month after injection,and the retinal morphology was examined by histopathology under the optical microscope.The ultrastructure of retinal ganglion cells （RGCs） was examined by the transmission electron microscope.The use and care of the animals complied with Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission.Results Cultured human ADSCs grew well with the slender polygone shape.Cell membranes showed the red fluorescence for PKH26 after induced.In addition,Pan-CK was expressed in the cell membranes with the red fluorescence in the induced cells,but the response was absent in the control cells.One month after intravitreal injection,induced cells located on the retinal surface,and the retinal morphology was clear under the optical microscope.No abnormality in RGCs was seen under the transmission electron microscope.Conclusions Human ADSCs can differentiate into RPE-like cells after induction.PKH26 can mark induced cells well.There is no adverse effect of induced cells on retina after intravitreal injection in a short-term duration in mice.