Topical growth factors and wound contraction in the rat: Part I. Literature review and definition of the rat model.

The isolation and production of growth factors and the observation that a platelet extract will promote wound healing in chronic wounds has led to an interest in the study of growth factors and wound healing. We wished to study the effect of platelet-derived growth factor on wound contraction. However, because studies of growth factors and wound contraction are quite recent, we could find only two models described in the literature and neither seemed ideal. Both used small wounds, which are difficult to measure, anesthetics with slow induction and recovery and which are difficult to titrate, and no dressings, which permits the animals to lick the wounds and possibly introduce other growth factors. We therefore reviewed wound contraction models used for other studies. In particular, we reviewed the animal used, anesthetic, wound size and shape, dressing methods, scab treatment, and measurement and comparison techniques. We then combined features of many of them into a model that solves the problems listed and permits the study of topically applied growth factors and wound contraction. The composite model to be described uses a large, circular wound on the rat, halothane anesthesia, and flexible, Tubigrip dressings.