According to study presented in Science Advances, a new approach of rejuvenating hair growth – using medication that are previously approved for safety – may be on the way.
Investigators at Columbia University Medical Center have identified that when hair follicles are suspended in a resting state, fast and robust development can be renewed by inhibiting a family of enzymes within the follicles.
Hair follicles do not generate hair regularly but instead cycle between 4 resting and growing phases.
Over 90% of the hair is generally in the growing phase, “anagen,” which can last from 2-6 years.
The relatively small catagen phase comes after, when the follicle regresses and goes toward the surface. “Telogen” is the resting phase, and “exogen” is when the hair falls out prior to the follicle resumes growth.
Commonly, the longer the hair, the longer the stages are; long hair is likely to grow more gradually.
Enzyme inhibitors promote growth
In studies with normal mouse and human hair follicles, Dr. Angela Christiano,colleagues identified that medication that inhibit the Janus kinase (JAK) family of enzymes promote fast and robust hair growth when directly employed to the skin.
This indicates that JAK inhibitors could be applied to recover hair growth in different types of hair loss, like as that caused by male pattern baldness – also known as androgenetic alopecia – and other kinds of hair loss that take place when hair follicles are trapped in a resting state.
Two JAK inhibitors have previously been permitted by the US FDA, one for treatment of blood related problems (ruxolitinib) and one more for rheumatoid arthritis (tofacitinib).
Both are being examined in clinical studies for the therapy of plaque psoriasis and alopecia areata, an autoimmune disease that strikes the follicles, resulting in hair loss.
It was while examining alopecia areata that the investigators chanced upon the impact of JAK inhibitors on hair follicles.
They had already identified that JAK inhibitors shut off the signal that leads to the autoimmune attack, and that oral types of the drug restore hair development in some individuals with the disorder.
Enzyme inhibitors enhance strong, quick hair development
In studies, the team recognized that mice grew more hair when the drug was given topically to the skin rather than when applied internally. This recommended JAK inhibitors may have a direct impact on hair follicles, additionally to inhibiting the immune attack.
Looking more carefully at normal mouse follicles of hair, they identified that JAK inhibitors quickly awakened resting follicles out of dormancy.
JAK inhibitors seem to induce the follicles’ normal reawakening procedure. Mice treated for five days with one of two JAK inhibitors sprouted new hair inside 10 days, significantly accelerating the hair follicle development phase. No hair growth was noticed on untreated control mice in the same time interval.
The inhibitors also develop longer hair from human hair follicles developed in culture and on skin grafted onto mice.
In light of these results, the investigators expect the drugs could generate new hair growth and increase the development of existing hairs in humans.
Dr. Christiano states that:
“What we have identified is promising, although we have not yet shown it is efficient for male pattern baldness. More work requires to be done to examine formulations of JAK inhibitors particularly made for the scalp to identify whether they can stimulate hair development in humans.”
It is not yet identified if JAK inhibitors can reawaken hair follicles that have been halted in a resting state due to androgenetic alopecia – which impacts both males and females – or other types of hair loss. So far, all the tests have been performed in normal mice and human follicles.
Dr. Christiano describes that very few substances can push hair follicles into their growth cycle so rapidly. Some topical agents generate tufts of hair here and there after a few weeks, but really few have such a strong and rapid-acting effect.