Have researchers found a real cure for baldness?

Researchers at Columbia University have discovered that certain immunomodulatory drugs, when applied to the skin, can waken hair follicles from their resting state and promote rapid, robust hair growth. The discovery raises the possibility that these enzyme inhibitors—two of which are already FDA approved for other indications—could eventually be used to restore hair loss from male pattern baldness and other types of hair loss.

In this investigation, researchers at Columbia University Medical Center in New York, NY, tested mice and human hair samples using drugs that inhibit the Janus kinase (JAK) family of enzymes. The JAK inhibitors promoted hair growth by stimulating hair follicle stem cells, the researchers concluded. Their results were published online October 23, 2015 in Science Advances.

“What we’ve found is promising, though we haven’t yet shown it’s a cure for pattern baldness,” said Angela M. Christiano, PhD, Associate Professor of Molecular Dermatology at Columbia. “More work needs to be done to test if JAK inhibitors can induce hair growth in humans using formulations specially made for the scalp.”

Dr. Christiano and colleagues reported last year that oral forms of JAK inhibitors shut off the signal that provokes autoimmune-induced alopecia areata, and restores hair growth in some people with the disorder.

While doing those experiments, Dr. Christiano noticed that mice grew more hair when the drug was topically applied to the skin than when the drug was given systemically. This indicated that JAK inhibitors might be doing something to the hair follicles in addition to stopping the immune attack.

When the researchers looked more closely at normal mouse hair follicles, they found that JAK inhibitors rapidly awakened resting follicles out of the dormant (telogen) phase and triggered the follicles’ normal reawakening process (anagen phase).

In this study, mice treated for 5 days with one of two JAK inhibitors sprouted new hair within 10 days, greatly accelerating the onset of hair growth. No hair grew on control mice within the same amount of time.

“There aren’t many compounds that can push hair follicles into their growth cycle so quickly,” said Dr. Christiano, who herself has alopecia areata. “Some topical agents induce tufts of hair here and there after a few weeks, but very few compounds have this potent an effect so quickly.”

In another experiment, the drugs also produced longer hair from human hair follicles grown in culture and on skin grafted onto mice.

The drugs likely act on the same pathways in human follicles as they do in mice, suggesting they could induce new hair growth and extend the growth of existing hairs in humans.

“So that opens up the possibility of treatment of a wide range of hair disorders, not simply male pattern or female pattern hair loss, but in other groups of disorders [such as] chemotherapy-induced alopecia, where the hair follicles are arrested, or other types where the hair grows for a short time, such as short anagen syndrome, and you’d like to be able to extend that hair growth cycle,” Dr. Christiano said.

Whether JAK inhibitors can reawaken hair follicles that have been dormant due to androgenetic alopecia (which causes male and female pattern baldness) remains to be seen.

“Other compounds have come and gone, but none of those are still on the market for male pattern baldness,” Dr. Christiano cautioned. “So there’s a lot of work that still has to be done to even begin to test that.”

Of the two currently-approved JAK inhibitors tested in this study, ruxolitinib is indicated for the treatment of blood diseases, and tofacitinib is indicated for rheumatoid arthritis. Both are now being tested in clinical trials for the treatment of plaque psoriasis and alopecia areata.