Evaluation of Stem Cell Components in Retrocorneal Membranes

The purpose of this study was to elucidate the origin and cellular composition of retrocorneal membranes (RCMs) associated with chemical burns using immunohistochemical staining for primitive cell markers. Six cases of RCMs were collected during penetrating keratoplasty. We examined RCMs with hematoxylin and eosin (H&E), periodic acid-Schiff (PAS) staining and immunohistochemical analysis using monoclonal antibodies against hematopoietic stem cells (CD34, CD133, c-kit), mesenchymal stem cells (beta-1-integrin, TGF-beta, vimentin, hSTRO-1), fibroblasts (FGF-beta, alpha-smooth muscle actin), and corneal endothelial cells (type IV collagen, CD133, VEGF, VEGFR1). Histologic analysis of RCMs revealed an organized assembly of spindle-shaped cells, pigment-laden cells, and thin collagenous matrix structures. RCMs were positive for markers of mesenchymal stem cells including beta-1-integrin, TGF-beta, vimentin, and hSTRO-1. Fibroblast markers were also positive, including FGF-beta and alpha-smooth muscle actin (SMA). In contrast, immunohistochemical staining was negative for hematopoietic stem cell markers including CD34, CD133 and c-kit as well as corneal endothelial cell markers such as type IV collagen, CD133 except VEGF and VEGFR1. Pigment-laden cells did not stain with any antibodies. The results of this study suggest that RCMs consist of a thin collagen matrix and fibroblast-like cells and may be a possible neogenetic structure produced from a lineage of bone marrow-derived mesenchymal stem cells.

Argon Laser Photocoagulation Combined With Subconjunctival and Intravitreal Bevacizumab Injections for a Retrocorneal Neovascular Membrane

PURPOSE: To report a case of retrocorneal membrane effectively treated with focal argon laser photocoagulation combined with subconjunctival and intravitreal bevacizumab injections. CASE SUMMARY: A 69-year-old female presented with persistent ocular pain and decreased visual acuity of the right eye following a complicated extracapsular cataract extraction performed nine months earliet. On examination, there was a neovascular retrocorneal membrane covering the superior one-third of the cornea with a sutured wound along the limbus. Following unresponsive conservative treatment, we performed focal argon laser photocoagulation followed by subconjunctival and intravitreal bevacizumab injections (1.25 mg). Two weeks later, markedly regressed neovascularization was noted. Additional argon laser photocoagulation, subconjunctival and intravitreal bavacizumab were performed six weeks later. Four months after the last treatment, the neovascular component substantially decreased and fibrous scar tissue replaced the neovascularization. The retrocorneal membrane showed no progression.