Many hair growth disorders are caused by the inability of hair follicles to re-enter the growth phase of the hair cycle, known as anagen.
Researchers from Columbia University, New York, have found that an existing class of drugs called JAK inhibitors can reactivate hair follicle stem cells when applied topically.
In mice, suppression of JAK-STAT signalling led quiescent hair follicles to re-enter anagen, resulting in rapid hair growth. And, in human tissues, treatment led to up-regulation of genes associated with anagen and denser hair growth than control-treated samples.
The researchers, reporting in Scientific Advances (online, 23 October 2015)
, say their findings suggest that JAK inhibitors, which are already in clinical trials as a systemic treatment for alopecia, have a localised effect on the hair cycle and could be used topically to directly target stem cells.