Local injection of IFN-gamma reduces the number of myofibroblasts and the collagen content in palatal wounds

Wound contraction and scar formation after cleft palate surgery impair maxi llary growth and dentoalveolar development. Since myofibroblast numbers and scar formation are reduced by interferon-gamma (IFN-gamma) in the hearing of dermal wounds, the hypothesis was tested that local administration of IF N-gamma reduces the numbers of myofibroblasts and the elevated amount of co llagen during palatal mucoperiosteal wound healing. Standardized mucoperios teal excision wounds were made in the palatal mucoperiosteum of young rats. Either IFN-gamma or vehicle alone (sham group) was repeatedly injected int o the wound site between 4 and 29 days post-wounding. The results were comp ared with unmanipulated control wounds. Samples of wound tissue were prepar ed for biochemical and microscopic analysis. The hydroxyproline, sulfated g lycosaminoglycan and DNA contents of the wound tissues were analyzed bioche mically. The degree of re-epithelialization, tissue thickness, the numbers of myofibroblasts, and the amounts of elastin and collagen types I and III were evaluated on histological sections. Injection of vehicle alone affecte d almost all healing parameters, compared with the controls, and delayed th e wound-healing process. IFN-gamma stimulated re-epithelialization and decr eased the numbers of myofibroblasts when compared with vehicle-treated woun ds. It also decreased the hydroxyproline and glycosaminoglycan contents of 60-day-old wound tissue, but the histological characteristics of scar tissu e persisted. Therefore, IFN-gamma is able to reduce the numbers of myofibro blasts and the collagen content of scar tissue after palatal wound healing. It may be a promising pharmaceutical agent for the reduction of wound cont raction and scarring after cleft palate surgery.