Abstract
Abstract: :
Purpose: All guinea pig corneas xenografted into eyes of BALB/c mice become opaque and are rejected within 8 - 12 days. We wished to determine whether the opacity that develops in these corneal xenografts arises directly from loss of corneal endothelial (CE) cells. Methods: Guinea pig corneas were grafted orthotopically to eyes of BALB/c mice. Rejecting grafts were evaluated clinically and scored on a 0 - 5+ opacity scale and grafts representing each score interval were removed, stained with propidium iodide and anti-ZO-1 antibody, and evaluated by confocal microscopy for density of intact corneal EC and inflammatory cells adherent to the posterior endothelial surface. Results: Setting the density of CE cells on ungrafted guinea pig corneas at 100%, the density of CE cells on grafted guinea pig corneas varied from 0 to 75%. Corneal grafts with opacity 2 + displayed CE density from 50 to 75%; by contrast corneal grafts scored 3+ and 4+ possessed lower density of CE (20-25%). Rejected guinea pig corneas are scored 5+, and the CE density in these grafts was 0%. The number of CE cells was difficult to evaluate on corneal grafts with opacity 0-1+ (evaluated at 1-3 days after surgery) because of reduced expression of ZO-1 which marks the borders of endothelial cells. Inflammatory cells were present on the posterior surface of all xenografts scored 2 - 5+, but their numbers did not correlate with the degree of opacity. Conclusions: Clarity of guinea pig cornea xenografts does not bear a linear relationship with persistence of CE cells on the graft, nor with the number of inflammatory cells adherent to the posterior corneal surface. Thus, we propose that the extent of corneal xenograft opacity correlates either with CE cell dysfunction, or with changes in the stroma that scatter light.
Keywords: transplantation • cornea: endothelium