Histological and immunohistological investigations in human epiretinal membranes

Background: The exact mechanisms involved in the development of epiretinal membranes are still poorly understood. This study aimed to investigate human epiretinal membranes with the help of different histological and immunohistological methods in order to find new concepts for the development of these membranes. Methods: 79 epiretinal membranes of patients (28 male, 51 female) undergoing a pars plana vitrectomy were included in this study. The mean age of the patients was 67.3 +/- 12.1 years. Preoperative diagnosis was diabetic retinopathy (n = 57), panuveitis (n = 4), PVR-ablatio (n = 16) and Coats disease (n = 2). All epiretinal membranes were histological and immunohistological investigated (aquaporin and with smooth muscle actin [SMA]). Results: Within the investigated membranes very different cell and tissue structures were found. They varied from extracellular matrix-rich membranes to membranes with high cell density and proliferative activity (fibroblasts). In immunohistological studies highly differentiated vessel structures were identified (aquaporin-endothelial cells). A typical characterisation and comparison to clinical findings is demonstrated with the help of selected samples. Conclusions: Human epiretinal membranes vary in their histological structure according to their underlying disease. Histological and immunohistological investigations may help to characterise these membranes and to understand the complex origin mechanism of these structures. This provides the basis for further studies with potential antiangiogenic drugs.