THE EFFECTS OF AGING ON CUTANEOUS WOUND-HEALING IN MAMMALS

The dogma that cutaneous wound healing is impaired as a function of ag e is largely unsubstantiated. This can be attributed to poor experimen tal design of human studies, the lack of subject characterisation with the exclusion of disease processes, and the study of inappropriate an imal models. Structural and functional changes in skin with age have b een reported, such as a decrease in dermal thickness, decline in colla gen content, a subtle alteration in the glycosaminoglycan profile, and a loss of elasticity, but these reports are subject to the above crit icisms in addition to the often-neglected requirement for site specifi city. Wound repair can be thought of as a culmination of three major o verlapping phases: inflammation, proliferation and remodelling. The in flammatory process has not been studied systematically with respect to age, and despite a reported decline in cellular function and number, there is a confounding increase in the production of specific cytokine s involved in the process of repair. The proliferative phase is associ ated with a loss of cellular responsiveness to specific cytokines with a decline in motility and proliferation; however caution in interpret ing these findings is important as, for example, the definition of 'ag eing' is used rather loosely with the result that neonatal versus youn g adult cells are compared instead of young versus old adults. During remodelling, fibronectin and collagen production may increase with age , as may wound contraction; the deposition of elastin has not been ass essed and the resulting mechanical properties of the scar are controve rsial, not least because human in vivo studies have been ignored. The absence of a critical review on the effects of advancing age on would healing has conspired to permit the perpetuation of the belief that we ll defined tenets exist. This review aims to redress this imbalance an d to highlight the need for well designed research into an increasingl y important field.