| Background Proliferative vitreoretinaopathy(PVR) after rhegmatogenous retinal detachment is a series of cellular events that include dedifferention, migration, proliferation,and production of extracellular matrix(ECM), followed by membrane formation and traction along surfaces of the detached retina resulting in failure of surgical retinal reattachmenL Retinal pigment epithelial cells(PRE) are major proliferative cells in PVR, Furthermore, the imbalance of growth factors.such as platelet-derived growth factor(PDGF) in eye is also play an important role in PVR. a-Smooth muscle actin(a-SMA) is one of the components of cytoskeleton , located in cell plasma of different types of cell, It is essential for the normal growth, maturation, differentiation, intergrity and function of its cells. It is related to migration and traction of cells, which contribute to the contraction of periretinal membrane. But the relationship between a -SMA and the degree of PVR is still unknown, and if PDGF stimutes the expression of a -SMA in RPE has not been reported.Purposes (1) To study the expression of Alpha-Smooth Muscle Actin( a -SMA) in the periretinal membrane(PRM) of PVR.(2) To investigate the effects of PDGF on the proliferation and migration of cultured human RPE, and if PDGF can increase the expression of a -SMA in RPE.Methods (1) 14 specimens of PRM were obtained during vitrectomies ofpatients suffered from different grades of PVR . " -SMA expression in PRM were detected by immunohistochemical staining, and quantitative analysis was performed by image process of immunofluorescence. (2) Cultured RPE of the 4-6th passage were devided into two groups DMEM(Delbecco's modified Eagle's medium) and 20g.L-1FCS+DMEM(2%DMEM) with or without PDGF (0.1 ~ l00ug- L-1). RPE proliferation was mesured by colorimetric assay for cellular growth and survivalfJVTlT assay), and Migration was assessed by using an in vitro wound healing model in which a small area of a confluent monolayer of hRPE was denuded with a razor blade.the cultures were subsequently incubated with medium, migration was measured after 12, 24, 36, 48 h as the number of cells that had entered the denuded area. (3) u -SMA expression in RPE were detected by immunohistochemical staining, and quantitative analysis was performed by image process of immunofluorescence.RESULTS (i)?SMA expression was detected in all 14 PRMs. The distributions of n -SMA were present in the cytoplasma, and accordance with the direction of stress fibers.. " -SMA expression was stronger in PVR/D than in PVR/C.(2) Proliferation: PDGF stimulated the proliferation of hRPE. The maximum proliferation rate of RPE was 153% at 10ug- L-1 in DMEM and 174% at 50-l00ug-L-1 in 2% DMEM. ?Migration: PDGF also stimulated hRPE migration in a dose and time-dependent manner. At 50~l00ug-L-1 , the maxium migration rate were 510% and 640% in DMEM and 2%DMEM. (4) The total fluorescent qualitity of u -SMA were 21.36 and 17.23 at 50ug-L-1 in 2% DMEM and DMEM, respectively, and 10.08 at Opg-L1 in DMEM. PDGF increased the expression of a -SMA in a dose- dependent manner.CONCLUTIONS (1) Expression of a -SMA was a common feature of PRM, and the expression correlated with severity of PVR and the process of membrane traction. ?PDGF can stimulate hRPE proliferation and migration, PDGF also increases the expression of u -SMA of RPE.The presence of serum can increase this effects, suggesting that PDGF may play an important role in thedevelopment of PVR...
|
PDF Full Text Request