AGING IS ASSOCIATED WITH REDUCED DEPOSITION OF SPECIFIC EXTRACELLULAR-MATRIX COMPONENTS, UP-REGULATION OF ANGIOGENESIS, AND AN ALTERED INFLAMMATORY RESPONSE IN A MURINE INCISIONAL WOUND-HEALING MODEL

The concept that aging impairs wound healing is largely unsubstantiate d, the literature being contradictory because of poor experimental des ign and a failure to adequately characterize animal models, This study tested the hypothesis that aging retards the rate of wound repair usi ng standardized cutaneous incisional wounds in a well-characterized ag ing mouse colony. Against the background of age-related changes in nor mal dermal composition, marked differences in healing were observed, I mmunostaining for fibronectin was decreased in the wounds of the old m ice, with a delay in the inflammatory response, re-epithelialization, and the appearance of extracellular matrix components, Heparan sulfate and blood vessel staining were both unexpectedly increased in the wou nds of the old animals at late time points. Despite an overall decreas e in collagen I and III deposition in the wounds of old mice, the derm al organization was surprisingly similar to that of normal dermal bask et-weave collagen architecture. By contrast, young animals developed a bnormal, dense scars. Intriguingly, some of these age-related changes in scar quality and inflammatory cell profile are similar to those see n in fetal wound healing. The rate of healing in young animals appears to be increased at the expense of the scar quality, perhaps resulting from an altered inflammatory response.