Abstract
Abstract: :
Purpose: To evaluate the effect of vitreous samples obtained from patients with human proliferative vitreoretinopathy (PVR) on morphology of retinal pigment epithelial cell induced collagen contraction combined with anti PDGF antibody. Methods: Human RPE cells were incubated on type II collagen gels mixed with vitreous taken from 14 patients. Anti PDGF antibody was added to one well of each duplicate pair. Positive and negative controls were similarly treated. Contracted gels were fixed at regular intervals (12, 24, 48, 96 hrs). Samples were fixed with glutaraldehyde, osmium tetroxide and stained with uranyl. Transmission electron microscopy was performed on all the samples. Results: Collagen gels mixed with vitreous samples contracted significantly in comparison to controls as well as gels mixed with anti PDGF antibody. EM examination of RPE revealed polarization of nucleus, loss of melanin, increased RER activity, increased actin concentration and fibroblastic transformation. In contrast RPE cell morphology was well preserved in samples with anti PDGF antibody. Quantitative analysis of differential morphology was statistically significant. (P<0.01) Conclusion: Contraction of fibroblastic RPE cells that have gained access to the vitreous is postulated to be the mechanism for development of PVR. PDGF in vitreous aspirates stimulates proliferation of RPE derived fibroblasts and promotes collagen contraction. Our data confirm that anti PDGF antibody is effective in inhibiting the transformation of RPE from epithelial form to mesenchymal form as evident by density of actin levels on electron microscopy. Therapeutic agents that neutralize the effect of PDGF may be helpful in preventing the development of PVR.
Keywords: 524 proliferative vitreoretinopathy • 567 retinal pigment epithelium • 629 vitreous