J Invest Dermatol.2004;122:7

Topical estrogen accelerates hair regrowth in mice after chemotherapy-induced alopecia..
Ohnemus U,et al.

Estrogen receptor ligands are important modulators of skin physiology and are involved in the control of normal hair regrowth. Here, we have studied the effects of topically applied 17-beta-estradiol on pathologic hair follicle cycling as seen during chemotherapy-induced hair loss, one of the major unresolved problems of clinical oncology. For this study we employed a well-established murine model that mimics chemotherapy-induced hair loss in humans. For precisely quantifying the area of hair loss and hair regrowth in this model in vivo, we developed a simple planimetric assayWe show that topical 17-beta-estradiol significantly alters the cycling response of murine follicles to cyclophosphamide, whereas the estrogen antagonist ICI 182.780 exerted no such effects. Initially, topical 17-beta-estradiol enhanced chemotherapy-induced hairloss significantly by forcing the follicles into the dystrophic catagen response pathway to hair follicle damage, whereas follicles treated by ICI 182.780 or vehicle shifted into the dystrophic anagen response pathway. Consequently, the regrowth of normally pigmented hair shafts after chemotherapy-induced alopecia was significantly accelerated in the 17-beta-estradiol treated group. Our data encourage one to explore topical estrogens as a potential stimulant for hair re-growth after chemotherapy-induced hair loss.