Sensitive Quantitative In Vivo Assay for Evaluating the Effects of Biomolecules on Hair Growth and Coloring Using Direct Microinjections into Mouse Whisker Follicles

The study developed a new method, the "whisker follicle microinjection assay", to evaluate the effects of biomolecules on hair growth and coloring using mouse whisker follicles. The researchers injected molecules directly into one side of the whisker follicles and measured the length and color intensity of the regrown whiskers. The chemicals minoxidil and ruxolitinib, and the protein RSPO1, promoted hair growth, with minoxidil's effect detectable at a concentration as low as 0.001%. The chemical deoxyarbutin inhibited melanin production, and the protein Nbl1 was identified as a new hair-growth inhibitor. This assay provides a sensitive and quantitative method to evaluate the effects of chemicals and proteins on hair growth and coloring.