A Scottish scientist and his wife report today they've achieved the world's first successful human hair transplant between people.
The experiment was laborious and the yield small--four hairs on the woman's arm grown from follicle cells taken from the man's head. Nevertheless, the effort suggests there may be a new strategy to restore hair lost through balding, disease or accident.
"In a normal hair transplant, you are basically redistributing hair follicles from one part of the scalp to another," said Angela M. Christiano, a geneticist at Columbia University who collaborated with the couple on the research, which was done in England. "You're born with a finite number of follicles, and you're basically just moving them around. This technology might allow you to grow new ones."
Apart from its theoretical use in cosmetic medicine, the experiment reveals that hair follicles are one of the rare tissues apparently capable of being transplanted from one body to another without rejection. Why evolution has endowed them with such "immune privilege" is a mystery.
The new technique involves the transfer of a thin film of cells from the "dermal sheath" surrounding the follicle, not a transfer of the hair itself. These cells would have to be grown in large quantities in cell culture for the technique to be a practical treatment for baldness. If that's possible, then presumably a person with some hair could donate to himself, and not have to look to someone else's head.
There are many other unanswered questions, as well. Nobody knows, for example, whether a hair grown from a transplant lasts as long as a native one. It's unknown whether the technique will work on scar tissue, such as that of people who've suffered burns. It's also unclear how the transplanted cells can be placed so that the resulting hair grows at an angle that lets it lie naturally on the scalp.
Scientists had previously stimulated hair growth in laboratory animals by transplanting follicle cells. This was the first time it was done in people. It was reported in the journal Nature.
In the experiment, several follicles were removed from the head of Colin A.B. Jahoda, a biologist at Durham University in England. The researchers then dissected out the layer of cells that forms a well in which the base of the hair sits. This work was done under a microscope with diamond knives and tiny blown-glass instruments. Only a couple of follicles can be done per hour.
The dermal sheath cells were then transplanted into a tiny incision on the inner forearm of Amanda J. Reynolds, Jahoda's wife, who is also a biologist at Durham University. The area was free of the thick-caliber hair found on the head, and had two small birthmarks, which acted as landmarks.
Reynolds taped a small plastic ring over the area, creating a protective tent. In four weeks, a hair with the characteristics of scalp hair appeared. In all, three sites on Reynolds's arm were planted with dermal sheath cells, and each took. One produced two hairs, and the others one each.
About 70 days after the transplant, the new hairs were surgically removed and analyzed. Curiously, a structure called the "dermal papilla" from which the hair grows was found to contain cells from both Jahoda and Reynolds. This suggests the recipient may have some say in the new hair's characteristics, such as color and texture. However, only more and bigger transplants will answer the question, Christiano said.
The hair transplants now performed for balding involve moving small plugs of skin, each containing numerous hairs, from the base of the scalp. They are then moved to the area of baldness, which in men is usually the top and front of the scalp.
A normal head hair goes through a cycle of growth and maturity lasting several hundred to a thousand days. It then falls out--50 to 100 are lost each day--and is replaced by a new hair that arises from the same follicle.
Because the hair grown through the new technique was removed so early, the researchers don't know whether it will "cycle" like normal hair. But even if the hair is not replaced at the end of its life, the technique might still have consumer appeal, Christiano speculated.
"I wouldn't be surprised if there are individuals who would be willing to come in every couple years for new implants," she said.
Jahoda has patented the follicle cell transplant technique, but hasn't sold a license for its use to a company, she said.