PROTEOGLYCAN DISTRIBUTION DURING HEALING OF CORNEAL STROMAL WOUNDS INCHICK

Proteoglycan distribution during corneal stromal healing in growing co rneas of young chicks were histologically and immunohistochemically an alysed. Single linear incisions to produce partial-thickness wounds we re made in the corneas of 5 day old chicks. The corneas were harvested at different times after wounding and processed for either histochemi cal analyses using periodic acid-Schiffs reaction (PAS) or for indirec t immunofluorescence analyses of lumican, keratocan, keratan sulfate, perlecan and laminin. Linear corneal stromal incisions were completely covered by migrated stratified epithelium by day 2 post wounding and resulted in a gaping wound with a thinner stroma. New stromal scar tis sue formed between the epithelium and the original stroma that resulte d in partial restoration of stromal thickness. During the first two to three weeks of healing, the stromal tissue filling the depression for med from the gaping wound, was hypercellular and PAS positive, indicat ing significantly higher levels of glycoprotein content but no new Bow man's membrane was formed. By four weeks, the scar tissue occupied a 2 -3 mm wide region. Immunofluorescence analyses indicated that other ma jor differences in the healing and normally growing stroma were the in creased synthesis and deposition of perlecan and laminin. No differenc es were evident in the immunfluorescence for keratocan or keratan sulf ate in the scar tissue, but the scar tissue did contain markedly decre ased levels of lumican. Thus, the regulation of proteoglycan and glyco protein synthesis is altered in the keratocytes that are recruited to the wounded regions in the growing corneal stroma of post-hatched youn g chicks. While synthesis and deposition of adhesive molecules includi ng laminin and perlecan are elevated, the synthesis of one of the kera tan sulfate proteoglycans, lumican, is reduced in the scar tissue as c ompared to the normally growing stroma. (C) 1998 Academic Press.