Abstract
Abstract: :
Purpose: Corneal graft survival depends critically on the quality of endothelium. In this study, we aimed to evaluate corneal endothelium in mice at different times after transplantation and to correlate endothelial integrity with corneal graft survival and infiltration of macrophages. Methods: Endothelial monolayer and macrophages infiltration of syngeneic and allogeneic (H-2b to H-2d) murine corneal grafts was evaluated using anti-actin and anti-F4/80 immunohistochemistry and quantitative image analysis of corneal whole-mounts by confocal microscopy. Grafts were assessed at different times (day 0 – 60) after transplantation and percentage of graft endothelium correlated with the degree of corneal opacity, the major determinant of graft rejection. Corneas from untreated mice served as controls. Results: The endothelial monolayer remained at all time-points intact (90% coverage) in control, excised non-transplanted (donor), and syngeneic transplanted corneas. In contrast, endothelium in allografts showed great variation in coverage (0 to 98%). In the immediate post-graft phase (1 to 48 hours), the endothelium remained intact over at least 65% of the allograft, whereas at later times (day 30, 60) maximal endothelial coverage was 45%. Clear grafts always retained at least 48% of the donor endothelium. Opaque grafts either had almost complete loss of endothelium or retained almost total coverage of endothelium. Macrophages were present in allografts with intact endothelium or with endothelial loss. Macrophages were also present in syngeneic corneas but in lesser numbers. Conclusions: In allografts, there is progressive loss of endothelium but the grade of corneal graft opacity does not consistently correlate with percentage of remaining endothelium. Both the duration post transplantation (>8 weeks) and the opacity grade should be considered when assessing corneal graft rejection in this model. Macrophages in allografts appear in larger numbers, suggesting that there is preferential activation compared to syngeneic grafts.
Keywords: cornea: endothelium • transplantation • microscopy: confocal/tunneling