Scientists transplanted scalp cells from one person to another and, for the first time ever, grew new hair on a human without the use of drugs. The approach could someday enable just about any head to sprout hair, researchers said.

The researchers, led by biologist Colin Jahoda at Durham University, in Britain, took cells at the bottom of hair follicles from Jahoda's own scalp and from a colleague's. These cells from the so called dermal papilla were then transplanted into the forearm of Jahoda's wife, Amanda Reynolds. Within five weeks, the transplanted tissue - no bigger than the head of a pin - made a total of five fully grown hairs in the Amanda's arm. 'It does show the potential of being able to induce new hair follicles in human skin which I don't think has been done before.' said Colin Jahoda. The transplanted tissue 'is telling the cells of the recipient: You will make a new hair follicle,' Jahoda said. The new hair was genetically male. It was longer, thicker and darker than arm hair, but it combined some characteristics of both donor and recipient.

Although the research was originally designed to test whether the graft would be rejected by the genetically unrelated woman, the researchers were pleased by the surprising results. 'You can use a few cells to basically regenerate an entire organ. To me, that's the mind-blowing part,' said Angela Christiano, a Columbia University baldness researcher who did the genetic analysis for the British experiment, reported in the journal Nature. DNA samples taken from the newly sprouted hair contained the Y male chromosome, proving that the new hair was from the man's cells.

The new work suggests the possibility of a quick 'hair cloning' procedure with the creation of new hair in just about anyone. The cells could be removed from a person's own scalp or, if that person cannot produce good quality cells, they could be collected from someone else. They could then be multiplied through laboratory cloning before being transplanted.

'Having the hair as an immunologically privileged organ would be very, very important,' said Dr. Michael Bernstein, a hair transplant surgeon who is medical director of the New Hair Institute in Los Angeles. He said Jahoda's technique may give hope mainly to old people who want new hair, patients with bad burns, or others who for genetic reasons fail to make their own hair. He predicted that bald men will be able to have their own hair cloned within 15 years or so.

The ability to induce new hair follicles by using dermal papilla cells has been done previously in animal models. In fact we have known about the ability to make new hair follicles using cells derived from other hair follicles since the late 1960s. However, this is the first time that the technique has been successfully used in humans.

Even more interesting from the scientific point of view is that the hair follicles were made in a woman using cells derived from a man. Normally the foreign cells would be rejected by the recipient. But the scientists suspect the cells taken from the base of follicle may have some type of immune privilege which allows them to mix with foreign cells. So instead of being rejected by the woman's immune system, the male cells interacted with her cells to create new follicles.

It is not yet clear whether such newly grown hair will last, pop up at the correct angle or satisfy other requirements for a cosmetically acceptable treatment. The microsurgery used in the experiment is complex, time consuming, and expensive right now. However, it could potentially be developed into a relatively simple procedure. The greatest problem facing developers will be to work out how to get the new hairs to all grow at an appropriate angle to line up with the natural hair follicles on our scalps. To do this will require that we understand much more about the gene expression involved in the induction of new hair follicles and what genes tell the hair to grow in a certain direction.

There is also the possibility that injecting cells that can induce new hair follicles might also induce tumor development and skin cancer in a few people. Such concerns will have to be addressed before the treatment method becomes available to the general public.