Scientists say they have moved a step closer to banishing bald spots and reversing receding hairlines after human hair was grown in the laboratory.

A joint UK and US team was able to create new hairs from tissue samples.

Far more research is needed, but the group said its technique had the "potential to transform" the treatment of hair loss.

The study results were published in the journal Proceedings of the National Academy of Sciences.

There are baldness therapies including drugs to slow the loss of hairs, and transplants, which move hair from the back of the head to cover bald spots.

The scientists at the University of Durham, in the UK, and Columbia University Medical Centre, in the US, were trying to actually grow new hairs.

Their plan was to start with material taken from the base of a hair and use it to grow many new hairs.

Tricky feat

But human hair has been tricky to grow despite successes in animal studies.

Whenever human tissue was taken from the dermal papillae, the cells which form the base of each hair follicle, the cells would transform into skin instead of growing new hairs.

However, the group found that by clumping the cells together in "3D spheroids" they would keep their hairy identity.

Tissue was taken from seven people and grown in 3D spheroids. These were then transplanted into human skin which had been grafted on to the backs of mice.

After six weeks, new hair follicles formed in five out of the seven cases and some new tiny hairs began to form.

Prof Colin Jahoda, from Durham University, told the BBC a cure for baldness was possible but it was too soon for men to be hanging up the toupee.

"It's closer, but it's still some way away because in terms of what people want cosmetically they're looking for re-growth of hair that's the same shape, the same size, as long as before, the same angle. Some of these are almost engineering solutions.

"Yeah I think it [baldness] will eventually be treatable, absolutely."

He added: "It's hard to say exactly how long that would take, but the fact that we've done it now should reawaken interest."

Any future therapy would involve transplanting cells which have been grown in the laboratory so safety is a concern.

There would be a risk of infection and the cells could become abnormal, or even cancerous, while being grown.

Baldness cures may not be the first application of the research. Prof Jahoda believes the findings will be used to improve the quality of skin grafts used after severe burns.

Prof Angela Christiano, from Columbia University, said: "This approach has the potential to transform the medical treatment of hair loss.

"Current hair-loss medications tend to slow the loss of hair follicles or potentially stimulate the growth of existing hairs, but they do not create new hair follicles.

"Our method, in contrast, has the potential to actually grow new follicles using a patient's own cells."