Immunohistochemical analysis of unsutured and sutured corneal wound healing

Abstract

In the unsutured partial thickness penetrating wounds of the cornea, the epithelium migrates over the wounded stromal surface prior to the onset of stromal regeneration. To determine the possible affects of the epithelial ingrowth on the organization of the stromal scar tissues, the healing of unsutured and sutured wounds was compared immunohistochemically. Immunostaining patterns for fibronectin, types III, VI and VII collagen, keratan sulfate proteoglycan (KSPG), and intermediate filament-associated protein (IFAP 130) in fibroblasts, were analyzed in unsutured and adjacent sutured keratotomy wounds in monkeys, at 2–9 weeks after surgery. At 2–4 weeks, fibronectin, type III and type VI collagen showed a lamellar interweaving pattern across unsutured wounds that was absent in sutured wounds. Type VII collagen was detected along the entire depth of regenerated stroma in unsutured wounds, but not in sutured wounds indicating that the epithelium had formerly been present in the regenerated stroma in unsutured wounds. Fibroblasts in both types of wounds expressed IFAP 130, but staining was more pronounced in sutured wounds. At 5–9 weeks, cellular re-activation, as judged from the expression for IFAP 130, was concomitant with a loss of lamellar interweaving with fibronectin, type III and type VI collagen across unsutured wounds, and proceeded in a posterior to anterior direction. In contrast, in sutured wounds, lamellar interweaving was established in anterior to posterior direction. At all postoperative times, unsutured and sutured wounds showed minimal staining for KSPG in the anterior scar. The distribution patterns of fibronectin, type III and type VI collagen and IFAP 130 suggested that unsutured wounds obtain a more advanced wound repair compared to sutured wounds during the early stages of healing which is followed by ineffective wound remodeling from the posterior to anterior regions. In sutured wounds, effective wound repair may be established from the anterior to posterior regions, after a relatively long period of a disorganized state of the scar tissues. These observations suggest that the temporary presence of an epithelial plug within an unsutured wound and/or wound gaping induce a different stromal healing response from that in the sutured wounds, that results in an eventual ineffective wound repair.

Key Words:

• cornea
• wound healing
• collagen
• glycosamino-glycan
• radial keratotomy
• immunohistochemistry
• monkey