Coulson-Thomas Vivien Jane, Caterson Bruce, Kao Winston W-Y
Department of Ophthalmology, College of Medicine, Edith J. Crawley Vision Research Center, University of Cincinnati, Cincinnati, Ohio, USA.
Stem Cells. 2013 Oct;31(10):2116-26. doi: 10.1002/stem.1481.
Mucopolysaccharidosis (MPS) are a family of related disorders caused by a mutation in one of the lysosomal exoglycosidases which leads to the accumulation of glycosaminoglycans (GAGs). MPS VII, caused by a mutation in β-glucuronidase, manifests hepatomegaly, skeletal dysplasia, short stature, corneal clouding, and developmental delay. Current treatment regimens for MPS are not effective for treating corneal clouding and impaired mental development. We hypothesized that human umbilical mesenchymal stem cells (UMSCs) transplanted into the corneal stroma could participate in the catabolism of GAGs providing a means of cell therapy for MPS. For such treatment, human UMSCs were intrastromally transplanted into corneas of MPS VII mice. UMSC transplantation restored the dendritic and hexagonal morphology of host keratocytes and endothelial cells, respectively, and in vivo confocal microscopy (HRT-II) revealed reduced corneal haze. Immunohistochemistry using antibodies against heparan sulfate and chondroitin sulfate chains as well as lysosomal-associated membrane protein 2 revealed a decrease in GAG content and both lysosomal number and size in the treated corneas. Labeling UMSC intracellular compartments prior to transplantation revealed the distribution of UMSC vesicles throughout the corneal stroma and endothelium. An in vitro coculture assay between skin fibroblasts isolated from MPS VII mice and UMSC demonstrated that neutral vesicles released by the UMSC are taken up by the fibroblasts and proceed to fuse with the acidic lysosomes. Therefore, transplanted UMSCs participate both in extracellular GAG turnover and enable host keratocytes to catabolize accumulated GAG products, suggesting that UMSC could be a novel alternative for treating corneal defects associated with MPS and other congenital metabolic disorders.
黏多糖贮积症（MPS）是一类相关疾病，由溶酶体外切糖苷酶之一的突变引起，导致糖胺聚糖（GAGs）蓄积。由β-葡萄糖醛酸酶突变引起的MPS VII表现为肝肿大、骨骼发育异常、身材矮小、角膜混浊和发育迟缓。目前MPS的治疗方案对治疗角膜混浊和智力发育受损无效。我们推测，移植到角膜基质中的人脐带间充质干细胞（UMSCs）可参与GAGs的分解代谢，为MPS提供一种细胞治疗手段。为此，将人UMSCs基质内移植到MPS VII小鼠的角膜中。UMSC移植分别恢复了宿主角膜细胞和内皮细胞的树突状和六边形形态，体内共聚焦显微镜检查（HRT-II）显示角膜混浊减轻。使用抗硫酸乙酰肝素和硫酸软骨素链以及溶酶体相关膜蛋白2的抗体进行免疫组织化学分析显示，治疗后的角膜中GAG含量以及溶酶体数量和大小均减少。移植前标记UMSC细胞内区室显示UMSC囊泡在整个角膜基质和内皮中的分布。从MPS VII小鼠分离的皮肤成纤维细胞与UMSC之间的体外共培养试验表明，UMSC释放的中性囊泡被成纤维细胞摄取并与酸性溶酶体融合。因此，移植的UMSCs既参与细胞外GAG周转，又使宿主角膜细胞能够分解代谢蓄积的GAG产物，这表明UMSC可能是治疗与MPS和其他先天性代谢紊乱相关的角膜缺陷的一种新的替代方法。
