Research on Retinal Transplantation of Neural Progenitors

用钩针诱导成年大鼠视网膜机械性损伤。一个细胞悬浮液(包含90,000个神经干细胞)被缓慢注入玻璃体间隙。移植后1周、2周和4周取材进行免疫组织化学染色，机械损伤后移植的干细胞最早在移植后1周进入宿主视网膜。免疫组织化学研究显示，一周后，超过一半的移植细胞表达神经前体细胞的标志物Nestin，但不表达其他标志物。4周后，部分移植细胞出现微管相关蛋白(MAP)2AB、MAP5和胶质纤维酸性蛋白(GFAP)免疫反应，提示向神经细胞和星形胶质细胞分化的进程。然而，它们对HPC-1、Calbindin和视紫红质没有免疫反应，表明它们没有分化为成熟的视网膜神经元。免疫电子显微镜显示移植物和宿主细胞之间形成了突触样结构，通过机械损伤的操作，移植的干细胞可以整合并随后分化为神经元和神经胶质细胞，包括形成突触样结构。

Mechanical injury was induced in the adult rat retina by a hooked needle. A cell suspension (containing 90,000 neural stem cells) was slowly injected into the vitreous space. The specimens were processed for immunohistochemical studies at one, two and four weeks after the transplantation.After the mechanical injury, incorporation of the grafted stem cells in the host retinas was found as early as one week after transplantation. lmmunohistochemical studies showed that, at one week, more than half of the grafted cells expressed nestin, a marker for neural precursor cells, but not other markers. At four weeks, some grafted cells showed immunoreactivity for microtubule-associated protein (MAP) 2ab, MAP5, and glial fibrillary acidic protein (GFAP), suggesting progress in differentiation into cells of neuronal and astroglial lineages. However, they showed no immunoreactivity for HPC-1, calbindin and rhodopsin, suggesting that they did not differentiate into mature retinal neurons. lmmunoelectron microscopy revealed the formation of synapse-like structures between graft and host cells.By the manipulation of mechanical injury, the incorporation and subsequent differentiation of the grafted stem cells into neuronal and glial lineage, including the formation of synapse-like structures, can be achieved even in the adult rat retina.