Collagen gene expression and wound strength in normal and radiation-impaired wounds : a model of radiation-impaired wound healing

Poorly healing wounds result in significant morbidity postoperatively. Numerous attempts have been made to study wound healing in vivo to understand better the normal healing process and factors that impair healing. Animal models of wound healing have been developed to evaluate wound healing in a systematic and controlled setting. Incisional wounds are created in animals to mimic the surgical patient. They may then be evaluated by a variety of methods for degree of healing. To give insight into the mechanisms of wound healing impairment, we developed a model of impaired wound healing in guinea pigs using radiation applied to the skin surfaces only. Wound bursting strength, a direct measure of the force required to burst apart healing linear incisions, was measured. Collagen content, measured indirectly as collagen gene expression, was measured. Significant reductions in wound bursting strength were noted after radiation administration. Collagen gene expression was decreased in wounds 7 days after radiation, but recovered to control levels 14 days after irradiation. Our model enables the inclusion of irradiated and unirradiated skin flaps within the same animal, thus eliminating intra-animal variation when comparing impaired and normal wounds. Wound bursting strength analysis, combined with techniques aimed at elucidating changes at the molecular level, provides a useful tool for the study of factors that impair healing and potential treatments for resulting healing deficits.