研究人员从老鼠的胚胎中提取出了干细胞，并在实验室培育出的人造视网膜帮助下，将这些胚胎干细胞培育成了感光细胞。这一过程使得视杆细胞能发育出复杂的三维结构，而三维结构对于视杆细胞能正确“工作”非常重要。

    随后，他们将大约 20 万个人造视杆细胞移植进患夜盲症的老鼠视网膜内，这些老鼠的视网膜内缺乏这种可以在低光环境下提供视力的视杆细胞，结果新细胞完全同复杂的视网膜组织结合在一起。

    视网膜存在两种感光细胞：视锥细胞与视杆细胞，失去感光细胞是造成大量退行性疾病病患视力下降的“罪魁祸首”。研究人员表示，经过多年研究，科学家们已经能很好地处理干细胞，并诱导它们发育成不同类型的成体细胞和组织。但迄今为止，视网膜的复杂结构一直被证明很难在实验室中再生。而这项最新技术很好地模拟了细胞正常的发育过程，这意味着科学家能在正确的发育阶段将细胞挑选出来并进行纯化，以确保移植成功。

    此项最新研究的突破在于证明可以将由胚胎干细胞获得的感光细胞植入成年老鼠眼部， 这一研究为人类临床试验奠定了基础，有望使成千上万名由于丧失感光细胞而罹患退行性眼病的患者重见光明。

    推荐原文阅读：

    Nat Biotechnol. 2013 Aug;31(8):741-7. doi: 10.1038/nbt.2643. Epub 2013 Jul 21.

    Photoreceptor precursors derived from three-dimensional embryonic stem cell cultures integrate and maturewithin adult degenerate retina.

    Gonzalez-Cordero A, West EL, Pearson RA, Duran Y, Carvalho LS, Chu CJ, Naeem A, Blackford SJ, Georgiadis A, Lakowski J, Hubank M, Smith AJ, Bainbridge JW, Sowden JC, Ali RR.

    SourceDepartment of Genetics, UCL Institute of Ophthalmology, London, UK.

    Abstract

    Irreversible blindness caused by loss of photoreceptors may be amenable to cell therapy. We previously demonstrated retinal repair and restoration of vision through transplantation of photoreceptor precursors obtained from postnatal retinas into visually impaired adult mice. Considerable progress has been made in differentiating embryonic stem cells (ESCs) in vitro toward photoreceptor lineages. However, the capability of ESC-derivedphotoreceptors to integrate after transplantation has not been demonstrated unequivocally. Here, to isolate photoreceptor precursors fit for transplantation, we adapted a recently reported three-dimensional (3D) differentiation protocol that generates neuroretina from mouse ESCs. We show that rod precursors derived by this protocol and selected via a GFP reporter under the control of a Rhodopsin promoter integrate within degenerateretinas of adult mice and mature into outer segment-bearing photoreceptors. Notably, ESC-derived precursors at a developmental stage similar to postnatal days 4-8 integrate more efficiently compared with cells at other stages. This study shows conclusively that ESCs can provide a source of photoreceptors for retinal cell transplantation.