Hair Loss

Exp Dermatol. 2008;17:793

The C3H/HeJ mouse and DEBR rat models for alopecia areata…

Jing Sun, M.D., et eal

The C3H/HeJ inbred mouse strain and the Dundee Experimental Bald Rat (DEBR) strain spontaneously develop hair loss due to adult onset alopecia areata (AA), a cell mediated disease directed against actively growing hair follicles. The low frequency of AA and the inability to predict the stage of AA as it evolves in the naturally occuring C3H/HeJ model of AA can be converted into a highly predictable system by grafting full thickness skin from AA affected mice to normal haired mice of the same strain. The rat DEBR model develops spontaneous AA at a higher frequency than in the mouse model but they are more expensive to use in drug studies due to their larger size. Regardless of the shortcomings of either model, these rodent models can be used succesfully to screen novel or approved drugs for efficacy to treat human AA. Since the pathogenesis of AA follows the canonical lymphocytic co-stimulatory cascade in the mouse AA model, it can be used to screen compounds potentially useful to treat a variety of cell mediated diseases. Efficacy of various agents can easily be screened by simply observing the presence, rate, and cosmetic acceptability of hair regrowth. More sophisticated assays can refine how the drugs induce hair regrowth and evaluate the underlying pathogenesis of AA. Some drugs commonly used to treat human AA patients work equally as well in both rodent models validating their usefulness as models for drug efficacy and safety for human AA.

Keywords: alopecia areata, hair loss treatment, animal model, review, diphenylcyclopropenone, squaric acid dibutyl esterase,

Alopecia areata targets hair follicles in the actively growing (anagen) phase of the hair cycle. It is often associated with other systemic cell mediated diseases (2)…..Human AA involves patchy hair loss from any hair-bearing region of the body that may progress to total body hair loss. AA may wax or wane on different sites, or the same site, or frequently it will spontaneously resolve with no treatment. AA most commonly affects the scalp but other body regions may also be affected. Extensive or total hair loss involving the scalp is termed alopecia totalis. AA affecting sites in addition to the bald scalp is termed AT/AU or alopecia universalis (AU) if the entire body is affected. This spontaneous, patchy, potentially reversible, non-scarring, hair loss has been the focus of medical research for over 100 years. Only recently however, with access to many new biomedical and molecular tools, have efforts been made to clarify the pathogenesis, and treatment of hair loss due to alopecia areata.