Little C W, Castillo B, DiLoreto D A, Cox C, Wyatt J, del Cerro C, del Cerro M
Department of Neurobiology, University of Rochester School of Medicine, NY 14642, USA.
Invest Ophthalmol Vis Sci. 1996 Jan;37(1):204-11.
The Royal College of Surgeons (RCS) rat suffers from a well-characterized, early-onset, and relentless form of photoreceptor cell degeneration. It has been shown that allografts of retinal pigment epithelial cells from normal perinatal rats have rescue effects in this condition. In preparation for human application, the authors determined whether human fetal retinal pigment epithelium (RPE) grafts have a photoreceptor rescue effect in RCS dystrophic rat retinas.
Sheets of RPE from human fetal eyes (10 to 16 weeks gestational age) were isolated according to the authors' recently described method. Fragments of the RPE sheets were transplanted to the subretinal space within the superior hemisphere. Transplants were performed within the superior equatorial region of five dystrophic RCS rats, one eye per animal. A similar volume of vehicle was injected into the subretinal space of five age-matched control rats, again one eye per rat. All rats were immunosuppressed with daily injections of cyclosporine. Using light microscopy, photoreceptor cell nuclear profiles of superior equatorial (SE) and inferior equatorial (IE) regions of transplanted and sham-injected control animals were counted.
Four weeks after transplantation, a dramatic rescue effect was observed. Microscopically, presumptive donor RPE cells were seen as single pigmented cells and as cell clusters in the subretinal space. An outer nuclear layer three to four profiles thick was present in the area of the RPE transplant but was nearly absent in the rest of the retina, as well as in the retinas of control rats. The number of photoreceptor nuclear profiles per 100 microns was 34.7 +/- 2.2 (mean +/- SEM) in the SE region of transplanted rats and 3.5 +/- 1.4 in the same region of sham-injected rats. There were 3.0 +/- 1.0 photoreceptor nuclear profiles in the IE region of transplanted rats and 3.5 +/- 1.2 in the IE region of sham-injected eyes. No evidence of graft rejection was seen.
This study provides the first indication that transplanted human fetal RPE cells are able to rescue photoreceptor cells in a model of hereditary retinal degeneration.
皇家外科学院（RCS）大鼠患有一种特征明确、早发性且持续进展的光感受器细胞变性。研究表明，正常围产期大鼠的视网膜色素上皮细胞同种异体移植对此种情况具有挽救作用。为人类应用做准备，作者确定人胎儿视网膜色素上皮（RPE）移植在RCS营养不良大鼠视网膜中是否具有光感受器挽救作用。
根据作者最近描述的方法，从人胎儿眼（妊娠10至16周）分离出RPE片层。将RPE片层碎片移植到上半球的视网膜下间隙。在五只营养不良的RCS大鼠的赤道上区域进行移植，每只动物一只眼。将相同体积的赋形剂注入五只年龄匹配的对照大鼠的视网膜下间隙，同样每只大鼠一只眼。所有大鼠每日注射环孢素进行免疫抑制。使用光学显微镜，对移植和假注射对照动物的赤道上（SE）和赤道下（IE）区域的光感受器细胞核轮廓进行计数。
移植后四周，观察到显著的挽救作用。显微镜下，推测的供体RPE细胞在视网膜下间隙中表现为单个色素沉着细胞和细胞簇。RPE移植区域存在三到四层厚的外核层，但视网膜其余部分以及对照大鼠的视网膜中几乎没有。移植大鼠SE区域每100微米的光感受器细胞核轮廓数为34.7±2.2（平均值±标准误），假注射大鼠同一区域为3.5±1.4。移植大鼠IE区域有3.0±1.0个光感受器细胞核轮廓，假注射眼的IE区域为3.5±1.2。未观察到移植排斥的证据。
本研究首次表明，移植的人胎儿RPE细胞能够在遗传性视网膜变性模型中挽救光感受器细胞。
