Immunohistochemical study of angiogenesis and proliferative activity in epiretinal membranes.

Formation of epiretinal membranes (ERMs) is a serious complication of retinal diseases, the most important being proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). In this study, our goal was to (i) calculate the microvessel density (MVD), (ii) evaluate vascular endothelial growth factor (VEGF) expression and (iii) correlate angiogenesis with the proliferative activity as expressed by the expression of Ki67 marker, in both membrane types. We performed immunohistochemistry in 14 PVR and eight PDR membranes, using antibodies against CD34, VEGF, Ki67 and glial fibrillary acidic protein. PDR membranes presented higher average count of microvessels compared with PVR membranes (p = 0.0015). No differences were observed concerning VEGF expression (p = 0.1). The expression of Ki67 was not correlated with microvessel number or VEGF expression. Our study confirms the presence of vascularisation in PDR membranes, as well as the presence of VEGF even in avascular PVR membranes, suggesting that immunoreactivity for VEGF may not be accompanied by angiogenesis.