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Effect of platelet‐derived growth factor on rabbit corneal wound healing

Human recombinant platelet‐derived growth factor was evaluated with the use of wound healing models in New Zealand albino rabbits. The efficacy of the platelet‐derived growth factor dimers, AA, AB, and BB, was determined in corneal reepithelialization and anterior keratectomy models which examined the healing response in the presence or absence of the basement membrane. All dimers increased the rate of wound healing in both models at 100 µg/ml when compared with control; however, the platelet‐derived growth factor‐BB isoform showed the most dramatic increase in both studies. The strength of the healing stroma after incision was evaluated by means of a tensile strength model. Histologic evaluation of the stromal wound area after 9 days of healing showed a marked increase in the number of keratocytes within the wound bed of the corneas treated with platelet‐derived growth factor‐BB when compared with control corneas. In addition, at 9 days, the epithelial plug was still present in the control corneas but had been extruded to the surface by the granulation tissue in the platelet‐derived growth factor‐BB—treated corneas. These results are indicative of a more advanced stage of healing in treated versus control wounds at 9 days after the operation. A 30% increase in corneal tensile strength versus control was noted after 21 days of healing. Finally, in an in vitro gel contraction assay, platelet‐derived growth factor exhibited a dose‐dependent effect on the contraction of fibroblasts for doses ranging from 0.01 to 10 ng/ml. These results indicate that platelet‐derived growth factor is active in the corneal wound healing process.