Wound healing and aging.

From these observations and others not described in the article, it is clear that there are age-dependent differences in wound healing. Classically, observers have divided the response to injury into three large phases: inflammatory, proliferative, and remodeling. As indicated elsewhere in this volume, the inflammatory response is decreased with age, and undoubtedly this bears on some of the alterations in healing. The proliferative phase traditionally includes cell migration, proliferation, and maturation, all of which are changed with age. Remodeling encompasses the tertiary binding of collagen molecules, which is also altered with age. Although all of these stages of wound healing differ with age, the changes are qualitative. Events begin later, proceed more slowly, and often do not reach the same level. However, there are neither new events nor an absence of expected events. This is clearly evident by the ease with which the most radical elective surgical wounds heal in the elderly patient. The ability of the aged to heal so well illustrates, therefore, not that their healing processes are equal to those of the young, but rather that our healing capacity is far in excess of what is needed.