PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: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.
Authors: Ruchira Singh; M Joseph Phillips; David Kuai; Jackelyn Meyer; Jessica M Martin; Molly A Smith; Enio T Perez; Wei Shen; Kyle A Wallace; Elizabeth E Capowski; Lynda S Wright; David M Gamm Journal: Invest Ophthalmol Vis Sci Date: 2013-10-17 Impact factor: 4.799
Authors: Jong Min Kim; Hoyoung Lee; Jae Pil Shin; Jeeyun Ahn; Je Moon Yoo; Su Jeong Song; Sang Jin Kim; Se Woong Kang Journal: Korean J Ophthalmol Date: 2017-08-26
Authors: J V Glenn; H Mahaffy; S Dasari; M Oliver; M Chen; M E Boulton; H Xu; W J Curry; Alan W Stitt Journal: Graefes Arch Clin Exp Ophthalmol Date: 2011-11-13 Impact factor: 3.117
Authors: Nikolina Jovancevic; Soumaya Khalfaoui; Markus Weinrich; Daniel Weidinger; Annika Simon; Benjamin Kalbe; Marcus Kernt; Anselm Kampik; Günter Gisselmann; Lian Gelis; Hanns Hatt Journal: Front Physiol Date: 2017-11-30 Impact factor: 4.566