Angiostatic effects of corticosteroid on wound healing of the rabbit ear.

Wound healing is a complex biologic process with initial inflammation, granulation tissue formation, and matrix remodeling. We observed the relation between angiostatic effects and corticosteroid administration time in the rabbit ear chamber. Angiogenesis in the chamber was studied using a microscope-television system. Two experiments were undertaken to represent the systemic and the topical administration of steroids. In experiment 1, 10 mg of triamcinolone acetonide was injected three times intramuscularly (on the day of implantation of the chamber, and the 7th and 14th day after implantation). Vascularization in this group was significantly delayed at the 7th, 14th, and 21st days but no difference from controls was observed in the size and density of vessels after its completion. In experiment 2, 3 mg of triamcinolone acetonide was injected once into the skin adjacent to the chamber on the 10th day after installment of chambers or on the day of installment. In the former group, new vascular growth was delayed until the 21st day after installment. The hemorrhagic zone had narrowed and vascular dilation was observed. In the latter group, endothelial budding was delayed and vascular constriction occurred. New vascular growth was severely delayed and granulation filling of the chamber was not completed. These results suggest not only that the topical administration had the stronger inhibitory effect on neovascularization than the systemic administration but that the effect differed depending on the stage of wound healing. In view of this effect of this steroid, we should pay careful attention to the time when steroids are administered to patients.