Identification of cell types in human diseased corneas

Activated myofibroblasts and macrophages are often found in corneal wound models. The current study was performed to determine whether human diseased corneas that had active tissue remodeling and enzyme activities also possessed myofibroblasts, macrophages, major histocompatibility complex class II cells, and/or CD-68-positive cells.

Normal, keratoconus, keratoconus with hydrops, bullous keratopathy, map-dot-fingerprint dystrophy, failed grafts, and acid burn/neovascularized corneas were collected, frozen in OCT, sectioned, and stained with antibodies to alpha smooth muscle actin (myofibroblast marker), CD14 (macrophage marker), CD68 (lysosomal membrane marker), and HLA-DR (major histocompatibility complex class II cells). Selective histochemical stains identified lysosomal enzymes.

Normal and map-dot-fingerprint dystrophy corneas lacked antibody and enzyme staining. Keratoconus corneas were positive for CD68, HLA-DR, and lysosomal enzymes but were negative for CD14 and smooth muscle actin. Bullous keratopathy corneas had CD68-, CD14-, and HLA-DR-positive cells, relatively normal enzyme levels, and were smooth muscle actin-negative. Failed graft corneas had significant numbers of CD68-, CD14-, and HLA-DR-positive cells and increased acid phosphatase, but these corneas were smooth muscle actin-negative. Ulcerated and vascularized corneas had positive staining with all antibodies that were examined. Cultured stromal cells from normal corneas were CD68-positive, CD14-negative, and alpha smooth muscle actin-negative, and they produced lysosomal enzymes.

The current study demonstrates that increased presence of lysosomal enzymes, corneal remodeling, and fibrosis can occur in the absence of myofibroblasts and/or macrophages.