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| Columbia University's Angela Christiano |
Inhibiting the Janus kinase family of enzymes with a topical formulation of approved drugs played a direct role in promoting abundant hair growth, according to a team of investigators at Columbia University.
Angela Christiano headed up the research team showing that JAK inhibitors could restore hair growth in different forms of hair loss, both in mouse and human hair follicles, when applied directly to the skin.
The two JAK inhibitors that showed promise are already approved by U.S. Food and Drug Administration; ruxolitinib is used currently for the treatment of blood diseases, and tofacitinib for rheumatoid arthritis.
Last year, Christiano's team showed that JAK inhibitors could switch off the signal that mounts a host immune response against its own hair follicles that causes eventual hair loss, restoring normal hair growth.
Initially this finding was through an oral administration of the JAK inhibitor. But when they tried a topical administration they saw an improvement in hair growth, suggesting a dual effect of an autoimmune block and a direct interaction of the drug with the hair follicles.
The researchers pinned the actions of the drugs to a reactivation of dormant follicles and since hair cells are known to cycle between a resting and growing phase, restoring all to the latter may improve overall hair growth. After 5 days of treatment, mice with either JAK inhibitor saw new hair growth within 10 days.
"There are very few compounds that can push hair follicles into their growth cycle so quickly," said Dr. Christiano. "Some topical agents induce tufts of hair here and there after a few weeks, but very few have such a potent and rapid-acting effect."
As yet, the team has conducted their experiments in normal mice and human follicles and what remains to be seen is whether these hair growth-inducing drugs can benefit hair follicles arrested by androgenetic alopecia--the main cause of male and female pattern baldness.
"What we've found is promising, though we haven't yet shown it is effective for male pattern baldness," said Dr. Christiano. "More work needs to be done to test formulations of JAK inhibitors specially made for the scalp to determine whether they can induce hair growth in humans."
Their results were published this week in the online edition of Science Advances.