Effect of leukocytes on corneal cellular proliferation and wound healing

PURPOSE. To establish whether fucoidin, by blocking the adhesion of leukocy tes on the limbal vascular endothelium, prevents extravasation of the cells from the blood stream into the limbal stroma and the wounded area after co rneal injury. Successful leukocyte blocking enabled investigation of the in fluence of leukocytes on corneal cellular proliferation after corneal wound ing. METHODS. Thirty-two New Zealand White rabbits were used. Photorefractive ke ratectomy (PRK) and a standardized alkali corneal wound were used as models in two sets of experiments. In half of the injured rabbits fucoidin was us ed to prevent leukocytes from leaving the local vessels. The efficiency of the blocking technique was evaluated by counting the number of leukocytes i n the limbal and wounded corneal areas. Proliferating cell nuclear antigen (PCNA) was used as a marker for proliferative activity. RESULTS. The infiltration of leukocytes into the limbus and the cornea afte r PRK and alkali injuries can be blocked by fucoidin. The healing rate of c orneal epithelium after alkali burn was retarded in the absence of leukocyt es. PCNA expression was enhanced in the presence of leukocytes. Fucoidin pe r se had no influence on corneal cell proliferation and wound healing. CONCLUSIONS. Polymorphonuclear leukocytes (PMNs) can be prevented from ente ring the cornea in vivo by fucoidin after PRK and after alkali burn. The co rneal epithelial healing rate is delayed in the absence of PMNs in vivo, an d PCNA expression increases in the presence of leukocytes.