Intravitreal Neovascular Tissue of Proliferative Diabetic Retinopathy: An Immunohistochemical Study

Abstract

Intravitreal neovascular tissue in 8 cases of proliferative diabetic retinopathy was investigated using immunohistochemical techniques. All 8 cases yielded positive immuno reactivity for type II collagen (vitreous collagen). The intravitreal neovascular tissue was classified into two groups (A or B), depending upon the distribution of type II collagen. In group A (3 cases), blood vessels were entirely surrounded by vitreous collagen, and in group B (5 cases), the vessels proliferated on one side of a mass of vitreous collagen. Type I and III collagens were distributed diffusely within the extracellular space of the tissue, whereas type IV collagen and fibronectin (FN) formed a basement membrane-like foundation for the newly formed vessels. Glial fibrillary acidic protein (GFAP)-immunoreactive cells were not clearly detected in any of the cases. Neovascular tissue typically proliferated on the posterior vitreous surface (as found in group B), but was also found to penetrate the vitreous gel (as found in group A). As neovascular tissue proliferation proceeded, types I, III and IV collagens and FN were produced. Glial cells (GFAP-positive cells) were not essential for neovascular tissue formation.

Epiretinal Membrane of Proliferative Diabetic Retinopathy: An Immunohistochemical Study

“…It is note worthy that these glial cells formed a monolayer on the ERMs and were unrelated to the new vessels. We found previously that diabet ic intravitreous neovascular tissue did not contain glial cells [19], while it has been reported that GFAP-positive cells are present in the ERMs of diabetic retinopathy [13,20,21] and other diseases [22][23][24], These results suggest that glial cells may not necessarily play an important role in the development of neo vascularization in PDR.…”

“…In con trast, as we have recently reported [19], dia betic intravitreous neovascular tissue consists solely of vascular networks with some extra cellular matrix. Type II collagen is an essential component of not only diabetic intravitreous neovascular tissue [19] but also diabetic ERMs, as shown here. It is interesting that glial cells were found in the ERMs but were not related to new vessels in the tissue.…”

Basement membrane abnormalities in human eyes with diabetic retinopathy.

“…Preretinal membrane ECM has been shown to contain Types I, 11,111, and V collagen, tenascin, decorin, thrombospondin, fibronectin, with Type iV collagen, vitronectin, and laminin in microvessel BMs (Casaroli Marano et al, 1995;Hagedoni et al, 1993;Hosoda et al, 1992;Weller et al, 1992;Immonen et al, 1991;Scheiffarth et al, 1988;. In our study, most of the above components and, in addition, perlecan, bamacan, Types VI, VIII, XII, and XIV collagen were found in preretinal membranes (Figures 3a and 4; Table 1).…”

Opticin Exerts Its Anti-angiogenic Activity by Regulating Extracellular Matrix Adhesiveness

“…First, they provide a scaffold for the vascular invasion into the vitreous (8, 12); consequently, vitreous collagen always is present in preretinal neovascular complexes (13). Second, collagen stimulates angiogenesis through sustained signaling via the α 1 β 1 and α 2 β 1 integrins expressed on endothelial cells (ECs), leading to an initial and critical change in cell shape, contractility, and polymerization and arrangement of cytoskeletal actin into stress fibers (14–16).…”