The drug works by targeting a protein that inhibits the development and growth of many tissues, including hair follicles, said the study published in the journal PLOS Biology.
“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,” said project leader Nathan Hawkshaw from The University of Manchester in Britain.
The researchers found that the compound WAY-316606, which was originally developed to treat osteoporosis, has a dramatic stimulatory effect on human hair follicles.
The researchers said that the few drugs which are currently available for treatment of male-pattern balding have moderate side effects and often produce disappointing hair regrowth results.
The only other option available to patients in such a situation is hair transplantation surgery.
The researchers, therefore, sought to develop new ways to promote human hair growth.
The approach was to first identify the molecular mechanisms of an old immunosuppressive drug, Cyclosporine A (CsA).
Cyclosporine A has been commonly used since the 1980s as a crucial drug that suppresses transplant rejection and autoimmune diseases.
However, it often has severe side-effects, the least serious — but most interesting — of which is that it enhances cosmetically unwanted hair growth.
The team carried out a full gene expression analysis of isolated human scalp hair follicles treated with CsA.
This revealed that CsA reduces the expression of SFRP1, a protein that inhibits the development and growth of many tissues, including hair follicles.
The inhibitory mechanism is completely unrelated to CsA’s immunosuppressive activities, making SFRP1 a new and highly promising therapeutic target for anti-hair loss strategies.
The researchers then found that the compound WAY-316606, which was originally developed to treat osteoporosis, targets the same mechanism as CsA by specifically antagonising SFRP1.
When they treated hair follicles with WAY-316606, the unrelated agent also effectively enhanced human hair growth like CsA.
This led the researchers to conclude that external application of the osteoporosis compound or similar compounds to balding human scalp may promote hair growth to the same magnitude as CsA or even better, but without its side effects.
“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,” Hawkshaw said.
“This makes our research clinically very relevant, as many hair research studies only use cell culture,” he said, adding that a clinical trial is required next to tell us whether this drug or similar compounds are both effective and safe in hair loss patients.