Immunohistochemical methods to evaluate vitreoretinal scaring

Abstract

Abstract Purpose Formation of scarlike epiretinal membranes (ERMs) constitutes potentially the end stage of evolution of proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy (PDR) and idiopathic vitreoretinopathy. Among various cellular populations, ERMs contain cells with contractile features typical of myofibroblasts. Myofibroblasts have been described in granulation tissue during wound healing and in practically all fibrocontractive diseases, in which they participate in the generation of isometric tension and in the synthesis of extracellular matrix components; these phenomena are in turn responsible for granulation tissue remodeling and retraction. The main marker of the myofibroblastic phenotype is the expression of alpha‐SMA. The transforming growth factor‐beta1 and the ED‐A splice variant of cellular fibronectin, an extracellular matrix component, are key players of the complex process of myofibroblast differentiation. Methods Proteins were detected by means of immunohistochemical staining on paraffin sections from formol fixed tissues and double immunofluorescence staining on whole tissues. Samples were observed by using classical light and confocal microscopes. Results The presence of alpha‐SM actin‐positive myofibroblasts was associated with the expression of TGF‐beta1, TGF‐beta receptor II, and ED‐A FN in all types of ERMs studied. Conclusion The results furnish new data on the mechanism of alpha‐SM actin stimulation in fibroblasts in a human pathologic setting.