Choi T H, Tseng S C
Ocular Surface and Tear Center, Department of Ophthalmology, Bascom Palmer Eye Institute, Miami, Florida, USA.
Cornea. 2001 Mar;20(2):197-204. doi: 10.1097/00003226-200103000-00019.
To examine the role of epithelial cells in inducing the differentiation of keratocytes into myofibroblasts and to determine whether this effect may be inhibited by amniotic membrane matrix.
In vivo, a 9-mm diameter, partial-thickness corneal flap was created in 12 rabbit eyes (6 rabbits), which were equally subdivided into three groups. The first group was implanted with one layer of a 6-mm diameter human amniotic membrane, from which the epithelium had been removed by dispase. The second group received an implantation of dispase-treated amniotic membrane with cultured rabbit corneal epithelial cells. The third group received the same implantation as the second group except that the cultured corneal epithelial cells were sandwiched between two layers of membrane. All corneas were removed 2 weeks later and were subjected to Masson trichrome staining and immunofluorescence staining with monoclonal antibodies to alpha-smooth muscle (alpha-SM) actin for myofibroblasts and cytokeratins for epithelial cells. In vitro collagen gels impregnated with different types of human ocular surface fibroblasts were seeded with or without rabbit corneal epithelial cells before testing for gel contraction.
Positive staining of alpha-SM actin was noted only in keratocytes adjacent to corneal epithelial cells at the incision site and those grown on the basement membrane side of the amniotic membrane. Negative staining was noted when epithelial cells were removed by dispase or when cultured corneal epithelial cells were sandwiched between two layers of membrane. Gel contraction by fibroblasts was significantly promoted when epithelial cells were seeded on the gel. In the latter situation, positive staining of alpha-SM actin was noted in fibroblasts subjacent to epithelial cells but not in those impregnated in the gel.
Epithelial cells are capable of inducing the differentiation of adjacent fibroblasts into myofibroblasts; such an induction requires a close epithelial-mesenchymal contact. Amniotic membrane alone does not induce this effect and can help block such induction by epithelial cells.
研究上皮细胞在诱导角膜细胞分化为肌成纤维细胞中的作用，并确定羊膜基质是否能抑制这种作用。
在体内，于12只兔眼（6只兔子）制作直径9mm的部分厚度角膜瓣，将其平均分为三组。第一组植入一层直径6mm、已用dispase去除上皮的人羊膜。第二组植入经dispase处理的羊膜并接种培养的兔角膜上皮细胞。第三组植入与第二组相同，但培养的角膜上皮细胞夹在两层羊膜之间。2周后取出所有角膜，进行Masson三色染色及用抗α-平滑肌（α-SM）肌动蛋白单克隆抗体对肌成纤维细胞和抗细胞角蛋白对上皮细胞进行免疫荧光染色。在体外，在测试凝胶收缩前，将不同类型的人眼表成纤维细胞接种于含或不含兔角膜上皮细胞的胶原凝胶中。
仅在切口部位与角膜上皮细胞相邻的角膜细胞以及在羊膜基底膜侧生长的角膜细胞中观察到α-SM肌动蛋白阳性染色。当用dispase去除上皮细胞或培养的角膜上皮细胞夹在两层羊膜之间时，观察到阴性染色。当在上皮细胞接种于凝胶时，成纤维细胞引起的凝胶收缩明显增强。在后一种情况下，在上皮细胞下方的成纤维细胞中观察到α-SM肌动蛋白阳性染色，但在凝胶中包埋的成纤维细胞中未观察到。
上皮细胞能够诱导相邻的成纤维细胞分化为肌成纤维细胞；这种诱导需要上皮-间充质紧密接触。单独的羊膜不会诱导这种作用，并且可以帮助阻断上皮细胞的这种诱导作用。
