视网膜干细胞移植任重而道远

Retinal stem cell transplantation:hope and challenges

进行性视网膜感光细胞的死亡是许多视网膜变性疾病的共同特征。现有的治疗方法不能恢复已经丧失的视功能。视网膜干细胞移植研究的不断深入在为视网膜变性患者带来希望的同时也面临一些严峻挑战:如何获得理想的视网膜干细胞?如何诱导视网膜干细胞分化成视杆及视锥细胞?如何诱导移植的细胞与受体细胞形成功能性突触连接?感光细胞丧失的早期,内部的视网膜神经通路是完整的,新的感光细胞只需与双极细胞形成突触连接就能恢复完整的视网膜神经通路。而感光细胞替换通常比其它神经元更直接更容易。因为感光细胞是感觉神经元,只在一个方向上与双极细胞-水平细胞形成连接。另外,视网膜特殊的层状结构决定了视网膜外层的感光细胞层是视网膜干细胞移植最理想的位置。视网膜干细胞研究的进展、视网膜变性疾病的特征及视网膜的特殊结构让我们有理由相信,干细胞移植的成功将首先来自视网膜感光细胞移植。

A feature common to retinal degenerative diseases is irreversible photoreceptor loss. All current treatments can only slow or at most prevent disease progression but cannot restore visual function. Exciting advances in the field of retinal stem cells have brought much hope to patients with retinal degenerative diseases. But critical challenges, such as how to obtain ideal retinal stem cells, how to induce retinal stem cells to differentiate into photoreceptor cells, how to induce grafted cells to functionally reconnect with host retina, are existing. Theoretically photoreceptor replacement is more feasible than any other retinal neurons because it is a sensory neu- ron connected in only one direction to the horizontal-bipolar cells. In addition, the photoreceptor layer of the outer retina is ideally suit- ed to stem cell transplantation due to the optimal combination of ease of surgical access, combined with an ability to observe grafted ceils directly through the clear ocular media. With growing advances in the field of retinal stem cells, combined with the features of retinal degenerative diseases and special retinal architecture, we can certainly look forward to the success of retinal stem cell transplantation first from photoreceptor replacement.