Comparison of Ruxolitinib and a Collagen-Targeted PTH-Based Hair Cycle Stimulant on Hair Follicle Counts and Hair Growth in the C3H/HeJ Engrafted Mouse Model of Alopecia Areata

The study compared the effects of a single subcutaneous injection of parathyroid hormone-collagen binding domain (PTH-CBD) with daily oral administration of the Janus kinase (JAK) inhibitor ruxolitinib on hair follicle counts and hair regrowth in C3H/HeJ mice over 8 weeks. The results showed that PTH-CBD treated mice had an increased number of anagen hair follicles (p<0.05) and improved hair regrowth compared to those treated with ruxolitinib, despite similar immune cell infiltrate. The study also found increased beta-catenin production in hair follicles of PTH-CBD-treated mice. The data suggests that a single dose of PTH-CBD can promote similar hair regrowth to that of daily oral ruxolitinib, potentially by increasing beta-catenin production and stimulating anagen transition of hair follicles.