Going, going… (Image: Dan Pan/Getty Images)

We may now be a hair’s breadth away from a cure for baldness. For the first time, new human hairs have been coaxed into growing from specialised skin cells that can be multiplied in number to potentially create a full head of hair.

Hair-raising remedies for hair loss currently consist of hormonal drugs to slow the process and hair transplants – where a section of hair follicles is moved from one area of the head to another (see “Hair-raising therapies”).

Finding a way to grow more hair, however, has proved difficult.


Hair growth in adults occurs naturally in a process known as hair neogenesis – where cells called dermal papilla cells that span the top two layers of skin coax surrounding cells to form hair follicles. One reason hair loss occurs is when papillae stop working.

One way of replicating hair neogenesis is to isolate healthy dermal papillae from a hair follicle, put them into a culture to increase their number, and place the new papillae into skin where they reprogramme surrounding cells to produce new hair.

Stimulating growth

More than 40 years ago, researchers demonstrated that this technique could be used to stimulate new hair follicle formation in rats. However, attempts at replicating this process in humans have failed – dermal papillae appear to lose their ability to induce hair growth when they are multiplied.

Now, Colin Jahoda at Durham University, UK, and colleagues have managed to produce multiple dermal papillae that retain their specialised abilities by culturing the cells in a 3D rather than 2D system.

The team first took samples of skin tissue discarded from human hair transplants and dissected healthy dermal papillae from the hair follicles. These were then multiplied in a culture system of nutrients that hung in a thick drop from the bottom of a petri dish.

After 30 hours, each drop contained about 3000 dermal papilla cells. Between 10 and 15 drops were then injected into a sample of human neonatal foreskin, which was grafted onto a mouse. The team chose to use foreskin tissue as the recipient because it does not normally grow hair – meaning that the dermal papillae would be challenged to fully reprogramme skin cells to produce a new follicle.

After six weeks, the papillae from five of seven donors formed a new hair follicle from which hair grew. “The dermal papilla cells act as a collective group and restoring that collectivity in 3D helps bring these properties back,” says Jahoda. “It’s proof of principle for something that has been a roadblock for this particular clinical strategy for many years.”

When the team compared gene expression in 2D and 3D-cultured papillae, they found that 22 per cent of all the genes disrupted by the 2D culture were active in the 3D droplet.

Hair cloning

Jahoda says the process needs to be studied for longer to see if the reprogrammed skin cells continue to reproduce hair after it naturally falls out. The technique also needs to be improved so that hairs of the right size and appearance are reliably produced every time, because some of the hairs grew without any pigmentation.

The team hopes that the technique will lead to what has been called “hair cloning” therapy. But the end result might not even need any transplantation: Jahoda says that now they know more about which genes need to be expressed for the cells to function, there is the potential for drugs to be developed that reactivate dermal papillae that aren’t functioning properly but are still present in the skin.

Melanie McDowall from the University of Adelaide, Australia, agrees that a drug-based therapy may be the way forward: “The very cool thing about hair follicles is you already have a channel into them. So topical creams applied to your skin have a good chance of getting down into where they’re needed.”

This will make a big difference to the field of hair regeneration, says Christelle Adolphe from the University of Queensland, Australia. She says it will be exciting to see if the cells’ function can be fully restored so that they also stimulate the production of skin appendages such as sweat glands. She says this could help people who need to have skin transplants after severe scarring or burns.

Jahoda agrees. “Skin appendages can make a real difference not just to the appearance of replacement skin, but to its functional capabilities,” he says.

Journal reference: PNAS, DOI: 10.1073/pnas.1309970110

Hair-raising therapies The multi-billion-dollar hair replacement industry has had no shortage of wares to sell to men and women experiencing baldness. Hair transplant therapy is currently the most effective way of improving the look of hair that is thinning or receding. The technique involves removing hair follicles from one part of your head and implanting them in another. Bits of skin about 1 millimetre in diameter that contain between one and four follicles are rearranged to give the appearance of a more hirsute head. Another method is to tackle the underlying cause of male pattern baldness: a breakdown product of testosterone, called DHT. Finasteride, sold as Propecia by pharmaceutical giant Merck, is a drug taken orally that limits the effectiveness of the enzyme that converts testosterone into DHT. But it has potentially serious side-effects including impotence and an increased risk of developing a particularly serious form of prostate cancer. Yet another treatment is minoxidil, sometimes marketed as Rogaine. It was originally created to treat high blood pressure but was found to have the side-effect of increasing hair growth. It can slow hair loss in men and women, and can sometimes even reverse it, but how it works is still poorly understood. The creation of new hair follicles after birth is very rare. But it seems adult mammalian skin can sometimes be coaxed into making new hair follicles when wounded. When researchers cut the skin of mice and added Wnt proteins – signalling molecules usually involved in embryonic development – they saw the creation of brand new hair follicles in the wounds. The technique has not yet been translated to humans.