ISLAMABAD: A new method of restoring hair growth - using drugs that are already approved for safety - may be on the way.
Researchers at Columbia University Medical Center in New York have found that when hair follicles are suspended in a resting state, rapid and robust growth can be restored by inhibiting a family of enzymes inside the follicles. 
Hair follicles do not produce hair constantly but rather cycle between four resting and growing phases. 
More than 90% of the hair is normally in the growing phase, "anagen," which can last from 2-6 years. 
The relatively short catagen phase follows, when the follicle regresses and moves toward the surface. "Telogen" is the resting phase, and "exogen" is when the hair falls out before the follicle resumes growth. 
Enzyme inhibitors promote growth
In experiments with normal mouse and human hair follicles, Dr. Angela Christiano, PhD, and colleagues found that drugs that inhibit the Janus kinase (JAK) family of enzymes promote rapid and robust hair growth when directly applied to the skin. 
This suggests that JAK inhibitors could be used to restore hair growth in various forms of hair loss, such as that induced by male pattern baldness - also called androgenetic alopecia - and other types of hair loss that occur when hair follicles are trapped in a resting state. 
It was while studying alopecia areata that the researchers chanced upon the effect of JAK inhibitors on hair follicles. 
They had already found that JAK inhibitors shut off the signal that causes the autoimmune attack, and that oral forms of the drug restore hair growth in some people with the disorder. 
JAK inhibitors appear to trigger the follicles' normal reawakening process. Mice treated for 5 days
with one of two JAK inhibitors sprouted new hair within 10 days, greatly accelerating the hair follicle growth phase. No hair grew on untreated control mice in the same time period. 
The inhibitors also produce longer hair from human hair follicles grown in culture and on skin grafted onto mice. 
Dr. Christiano explains that very few compounds can push hair follicles into their growth cycle so quickly. Some topical agents induce tufts of hair here and there after a few weeks, but very few have such a powerful and rapid-acting effect.