Smith-Thomas L, Haycock J W, Metcalfe R, Boulton M, Ellis S, Rennie I G, Richardson P S, Palmer I, Parsons M A, Mac Neil S
University Department of Medicine, Clinical Sciences Centre, Northern General Hospital, Sheffield, UK.
Curr Eye Res. 1998 Aug;17(8):813-22.
The aim of this study is to explore the role of intracellular calcium in the mechanism of co-regulation of retinal pigment epithelial cells (RPE) by vitreous fluid and platelet mitogens, in order to evaluate the use of calcium modulating drugs in preventing RPE cell proliferation and contraction of fibrocellular membranes.
Monolayers of human RPE cells were loaded with Fura-2-AM and examined in a fluorimeter for changes in intracellular free calcium in response to platelet mitogens (PDGFAB or TGFbeta1) and vitreous fluid (containing vitreous substrate proteins), both alone or in combination. The effect of the calcium antagonists TMB8 and verapamil and the calmodulin antagonists J8 and tamoxifen were then examined on RPE cell proliferation and pigmentation, both in the presence and absence of vitreous substrate and platelet mitogens.
We report that co-exposure of RPE cells to platelet mitogens and vitreous fluid produces an increase in intracellular free calcium of greater duration than that with either PDG-FAB, TGFbeta1 or vitreous fluid alone. Calcium and calmodulin antagonists significantly reduce RPE cell proliferation in both the presence and absence of vitreous substrate and platelet mitogens. Calcium antagonists also stimulate the accumulation of autofluorescent granules within RPE cells.
Calcium signalling plays a role in the co-regulation of RPE cells by vitreous substrate and platelet mitogens. Drugs that lower intracellular calcium or inhibit calmodulin may offer an additional approach to preventing the hyperproliferation of RPE cells in PVR.
本研究旨在探讨细胞内钙在玻璃体液和血小板促细胞分裂剂共同调节视网膜色素上皮细胞（RPE）机制中的作用，以评估钙调节药物在预防RPE细胞增殖和纤维细胞膜收缩方面的应用。
用人RPE细胞单层加载Fura-2-AM，并在荧光计中检测其对血小板促细胞分裂剂（PDGFAB或TGFβ1）和玻璃体液（含玻璃体液基质蛋白）单独或联合作用时细胞内游离钙的变化。然后检测钙拮抗剂TMB8和维拉帕米以及钙调蛋白拮抗剂J8和他莫昔芬在有或无玻璃体液基质和血小板促细胞分裂剂存在时对RPE细胞增殖和色素沉着的影响。
我们报告，RPE细胞同时暴露于血小板促细胞分裂剂和玻璃体液时，细胞内游离钙的增加持续时间比单独使用PDG-FAB、TGFβ1或玻璃体液时更长。在有或无玻璃体液基质和血小板促细胞分裂剂存在时，钙和钙调蛋白拮抗剂均能显著降低RPE细胞增殖。钙拮抗剂还能刺激RPE细胞内自发荧光颗粒的积累。
钙信号在玻璃体液基质和血小板促细胞分裂剂对RPE细胞的共同调节中起作用。降低细胞内钙或抑制钙调蛋白的药物可能为预防增殖性玻璃体视网膜病变（PVR）中RPE细胞的过度增殖提供一种额外的方法。
