This is the first of three reviews of technical literature examining the fact and fancy of aging skin. The three topics are cutaneous blood flow, cutaneous biochemistry and skin thickness.
Changes in cutaneous blood perfusion with age, if present, could have profound effects on skin physiology, including alterations in concentration gradients for percutaneous penetration of compounds, alterations in diffusion of glucose and other nutrients to the epidermis, and implications for wound healing. While a decrease in blood flow to the skin is often an assumed effect of aging, little direct evidence-based knowledge exists.
This article reviews the research and attempts to provide a foundation for future study. Distinctions are not always easily made between intrinsic physiologic aging and extrinsic aging due to photo-exposure, wind, relative humidity and other environmental factors. Distinctions that can be made will be reported here.
This review results from a literature search on age-related changes in cutaneous blood perfusion conducted in PubMed, Em-Base, Science Citation Index and the UCSF dermatological library’s collection of books on the topic of aging skin. The review includes brief descriptions of commonly used quantitative methods and a discussion of research data.
Cutaneous blood perfusion has been quantitatively studied in vitro as well as in vivo. In vitro histologic methods include the study of frozen sections stained with alkaline phosphatase for microscopic analysis. However, this technique is older and gives only a two-dimensional view, tending to yield overestimates of actual cutaneous perfusion.1 A more recent immunohistochemical method studies specimens of skin stained for the CD31 antigen, the platelet endothelial cell adhesion molecule.