Researchers from the University of Manchester Centre for Dermatology Research have found a drug originally intended for osteoporosis could help treat human hair loss.

The researchers examined the molecular mechanisms of cyclosporine A (CsA), an immunosuppressant that has been in use since the 1980s to suppress transplant rejection and autoimmune diseases,  which has a side-effect of causing hair growth.

In their study, the researchers found CsA to have a significantly stimulatory effect on human hair follicles donated by patients undergoing transplantation surgery.

“Thanks to our collaboration with a local hair transplant surgeon, Dr Asim Shahmalak, we were able to conduct our experiments with scalp hair follicles that had generously been donated by over 40 patients and were then tested in organ cultures,” study leader Dr Nathan Hawkshaw said.

“This makes our research clinically very relevant, as many hair research studies only use cell culture. When the hair growth-promoting effects of CsA were previously studied in mice, a very different molecular mechanism of action was suggested; had we relied on these mouse research concepts, we would have been barking up the wrong tree.”

A full gene expression analysis was conducted on these donated scalp hair follicles, revealing CsA to inhibit the expression of SFRP1, a protein which prevents the development of tissues such as hair follicles.

CsA’s ability to block SFRP1 is unconnected to its immunosuppressive actions, making SFRP1 a promising drug target for future anti-balding therapies.

The research team then identified a compound originally developed for the treatment of osteoporosis, known as WAY-316606, which works in the same way as CsA by inhibiting SFRP1. When the donated hair follicles were treated with WAY-316606, hair growth was enhanced in a similar manner to that seen following CsA treatment.

“The fact this new agent, which had never even been considered in a hair loss context, promotes human hair growth is exciting because of its translational potential: it could one day make a real difference to people who suffer from hair loss,” Hawkshaw said.

“Clearly though, a clinical trial is required next to tell us whether this drug or similar compounds are both effective and safe in hair loss patients.”

Currently, the only treatments for male-pattern baldness (androgenetic alopecia) aside from hair transplantation surgery are the drugs minoxidil and finasteride. However, both have adverse side effects and often cause only moderately successful regrowth results.

Findings were published in the journal PLOS Biology.