A topical parathyroid hormone/parathyroid hormone-related peptide receptor antagonist stimulates hair growth in mice.

One of the biggest hurdles in developing peptides for the treatment of hair growth disorders is that there has been no effective method of delivering them topically. Murine hair growth can be stimulated with ip injections of the PTH/PTHrP receptor antagonist, PTH (7-34). We sought to determine whether we could deliver PTH (7-34) topically and achieve stimulation of hair growth. We prepared a topical cream by mixing PTH (7-34) into a liposome vehicle (Novasome A). We applied the cream daily to the backs of 5-wk-old female SKH-1 hairless mice for 1 wk. After the 1 wk of treatment, there was marked stimulation of hair growth in the SKH-1 hairless mice. Relative to controls, mice treated with PTH (7-34) had 216% longer hairs (P < 0.001), 40% more visible hairs (P < 0.001), and 43% more hair follicles stained with 5-bromo-2'-deoxyuridine (P < 0.01). A unique aspect of skin is the possibility to directly target it via topical treatment. Our study is the first to report the hair-stimulating effect of a PTH/PTHrP receptor antagonist topically applied to skin in vivo. Thus, we introduce a novel paradigm to develop topical PTH analogs for treating disorders of hair growth.