Hair loss and skin appearance can have a profound effect on individuals' psychological well-being and quality of life. Anti-aging products represent a high percentage of skin and hair care product sales in the U.S. and abroad, and sales are expected to rise in many Western markets having an aging demographic. (Lennard, “Hair Care Growth Thinning for Near Term,” Global Cosmetics Industry Magazine, May 2009.) Consumers seek these products to counteract age-related changes to epithelial biology that lead to skin imperfections (e.g., loss of elasticity, discoloration, dryness, and rough surface texture) and hair loss and thinning.
Thinning hair and significant hair loss, i.e., “baldness,” is regarded in many cultures as less attractive. Hair growth is a cyclical process consisting of a growth stage (anagen), a regression stage (catagen), and a quiescent stage (telogen). During anagen, the hair bulb within the follicle penetrates the dermis and contacts the dermal papilla, triggering division of hair matrix keratinocytes. The new keratinocytes dehydrate and condense to form the hair shaft, which is pushed through the epidermis by newly dividing keratinocytes in the hair root. Hair growth ends in the catagen phase. The hair bulb separates from the dermal papilla, retracts from the dermis, and the follicle shrinks in size. In telogen, the hair remains attached to the follicle but, due to its shallow position in the epidermis, can easily be released from the skin. Normally, the follicle transitions back into anagen phase, during which the hair is pushed out of the follicle by hair newly formed by dividing keratinocytes. Disruption of the hair growth cycle leads to thinning and baldness. On the scalp, hair follicles shrink and shed terminal (long, pigmented) hair. The lost hair is either not replaced by new hair or is replaced by vellus (thin, short, non-pigmented) hair, resulting in the appearance of baldness.
The most common pharmacotherapeutics currently used to treat hair loss are minoxidil and 5-alpha reductase inhibitors, such as finasteride. The precise mechanism by which minoxidil reduces hair loss is unknown, and there is a significant percentage of patients that do not respond to therapy. (Lack of efficacy of finasteride in postmenopausal women with androgenetic alopecia, Journal of the American Academy of Dermatology, 43 (5), 768-776 (2000).) While finasteride has been shown to slow hair loss in men, the drug is associated with several side effects, including gynecomastia and sexual dysfunction. Both minoxidil and anti-androgens can require several weeks to impact hair count, and must be continued indefinitely on a daily basis to maintain effectiveness.
Traditional methods to measure efficacy include the counting of the number of hair fibers in a given area from a photograph (e.g. 1 cm2). Additional analysis of the same physical site on the scalp from images taken at two separate time points (i.e. 48 hours apart) can reveal the growth phase of the individual hairs (i.e. anagen or telogen). It is generally understood that this there is a correlation in such data and its relationship to the loss and retention of hairs on the head.
Thus, there exists a need for materials and methods for reducing or delaying the effects of age on epithelial biology, particularly with respect to hair loss and/or hair retention.