Objective: To study the actions of platelet-derived growth factor (PDGF) in proliferative membrane formation of proliferative vitreoretinopathy (PVR) and whether there is the existence of PDGF secreting cells and target cells.
Methods: Seven epiretinal membranes (ERM) and 7 subretinal membranes (SRM) obtained from eyes undergoing pars plana vitrectomy for retinal detachment complicated by PVR were studied. A panel of polyclonal antibodies against PDGF-A and -B ligands, PDGF-alpha and -beta receptors, cytokeratin [the marker of retinal pigment epithelial (RPE) cell] and glial fibrillary acidic protein (the marker of glial cell) was used in immune electron microscopy to examine the expression of PDGF and PDGF receptors (PDGFR) in the membranes. The relationship of PDGF protein and the main cellular composition of ERM and SRM, retinal pigment epithelial and glial cells, was detected by using the double-labeling techniques of immune electron microscopy.
Results: Positive protein expression of PDGF-A located in the cytoplasm of some cells was detected in 7 ERMs and 5 of 7 SRMs. Positive protein expression of PDGF-B was detected in 7 ERMs and 5 of 6 SRMs, and it was located in the cytoplasm of some cells, especially in the secreting granules. RPE cells and glial cells were identified in ERMs and SRMs. PDGF receptors were not detected in the ERM and SRM in this research. Double-labeling of PDGF and cytokeratin showed that RPE cells were the secreting cells of PDGF. Similarly, double-labeling of PDGF and glial fibrillary acidic protein showed that glial cells were the secreting cells of PDGF.
Conclusions: PDGF can be secreted by the cells of ERM and SRM. PDGF plays an important role in the pathogenesis of PVR. RPE and glial cells are the secreting cells of PDGF. The results indicate that PDGF affects cellular behavior by autocrine or paracrine mode in the formation of PVR.