Braun M, Kage A, Heimann K, Schraermeyer U
Department of Vitreoretinal Surgery, University of Cologne, Germany.
Graefes Arch Clin Exp Ophthalmol. 1999 Jan;237(1):67-71. doi: 10.1007/s004170050196.
Many successful pigment epithelium transplantation studies involving pink-eyed Royal College of Surgeons (RCS) dystrophic rats showed highly pigmented transplanted cells forming a double layer with slightly pigmented cells, attached to Bruch's membrane. Since it is not clear whether transplanted pigmented cells can displace retinal pigment epithelial (RPE) host cells from Bruch's membrane, we suggested that RPE cells of RCS dystrophic rats can phagocytize melanin granules, possibly derived from perished transplanted cells.
In a series of three experiments, RPE cells of nine pink-eyed, 2 1/2-month-old RCS dystrophic rats were isolated by trypsinization and mechanical dissection and cultivated in Dulbecco's modified Eagles' medium. These cells were then fed with melanin granules, isolated from bovine RPE cells, double-trypsinized after phagocytosis and viewed by light and electron microscopy. We also transplanted iris pigment epithelial (IPE) cells of 20-day-old Long-Evans rats into the subretinal space of pink-eyed RCS dystrophic rats of the same age, shown in light-microscopic photography after 42 days.
Living RPE cells were heavily pigmented after feeding with isolated melanin granules in all three experiments as viewed by light microscopy. In addition, we identified melanin granules phagocytized by dystrophic RPE cells in electron microscopy. After transplantation of pigmented IPE cells into the subretinal space of pink-eyed RCS dystrophic rats' eyes, a layer of slightly pigmented cells was seen on Bruch's membrane below the transplanted IPE cells, shown in light microscopy.
We have shown by phagocytosis assay that dystrophic RPE cells can take up melanin granules in vitro. Our results assume that pigmented cells in transplantation studies, found as a monolayer, attached to Bruch's membrane, cannot automatically be identified as transplanted cells. Instead, the possibility of perished transplanted cells serving as melanin donors for RPE host cells must be taken into consideration.
许多涉及红眼皇家外科学院（RCS）营养不良大鼠的成功色素上皮移植研究表明，高度色素沉着的移植细胞与色素沉着较轻的细胞形成双层，附着于布鲁赫膜。由于尚不清楚移植的色素沉着细胞是否能将视网膜色素上皮（RPE）宿主细胞从布鲁赫膜上置换下来，我们推测RCS营养不良大鼠的RPE细胞可以吞噬黑色素颗粒，这些颗粒可能来自死亡的移植细胞。
在一系列三个实验中，通过胰蛋白酶消化和机械解剖分离出9只2个半月大的红眼RCS营养不良大鼠的RPE细胞，并在杜尔贝科改良伊格尔培养基中培养。然后用从牛RPE细胞中分离出的黑色素颗粒喂养这些细胞，吞噬后进行双重胰蛋白酶消化，并通过光学显微镜和电子显微镜观察。我们还将20日龄长 Evans 大鼠的虹膜色素上皮（IPE）细胞移植到同年龄的红眼RCS营养不良大鼠的视网膜下间隙，42天后进行光学显微镜摄影。
在所有三个实验中，光学显微镜观察显示，用分离出的黑色素颗粒喂养后，存活的RPE细胞色素沉着严重。此外，我们在电子显微镜下鉴定出营养不良的RPE细胞吞噬的黑色素颗粒。将色素沉着的IPE细胞移植到红眼RCS营养不良大鼠眼睛的视网膜下间隙后，在移植的IPE细胞下方的布鲁赫膜上可见一层色素沉着较轻的细胞，光学显微镜显示。
我们通过吞噬试验表明，营养不良的RPE细胞在体外可以摄取黑色素颗粒。我们的结果表明，在移植研究中发现的作为单层附着于布鲁赫膜的色素沉着细胞，不能自动被鉴定为移植细胞。相反，必须考虑死亡的移植细胞作为RPE宿主细胞黑色素供体的可能性。
