
I’LL level with you: a part of me didn’t want to write this story. When I first realised that I was losing my hair, I found it important to mention it often in conversation. I was so embarrassed about it that I was trying some sort of reverse psychology. But I soon realised that if there was one thing less attractive than my balding head, it was how much I was talking about it. I am joking, of course: there is nothing wrong with being bald. Still, for me, the prospect is terrifying. My hair is a big part of my identity, so to lose it is crushing.
I’m not alone. By the age of 50, between 30 and 50 per cent of men have begun to experience male pattern baldness. Despite there being plenty of handsome hairless men out there – I’m looking at you, Thierry Henry – studies suggest that people tend to perceive bald men as less attractive and less friendly. And we don’t need science to tell us that this can be deeply upsetting.
So although I have dialled down the discussion of my growing bald patch, I have been quietly digging into the science of hair loss – and what I found is worth shouting about. It is common knowledge that some treatments can slow hair loss. What is less known is that as we are coming to understand the reasons why male pattern baldness causes people to lose their hair, we are finding new strategies to restore it. There may soon be a way to not just slow balding, but reverse it.
In a field where tales of miracle cures are ten a penny, it is important not to overpromise. Still, there is a sense that the science of hair is advancing at breakneck speed. “People are now starting to get excited that we’re reaching a tipping point,” says biologist Maksim Plikus at the University of California, Irvine.
What is baldness?
There are many reasons why people lose hair from their heads. It can happen suddenly after an infection or chemotherapy. Sometimes, people can lose patches of hair through an autoimmune condition called alopecia areata. But the most common type is androgenetic alopecia, or male/female pattern baldness. In men, we know that the condition, in which hair loss begins around the crown and forehead, is related to male sex hormones, but we don’t understand the exact trigger.
The female version tends to cause an overall thinning that rarely progresses to total baldness. It is also thought to be caused by sex hormones, but again the mechanics elude us.
Through the ages, people have looked to a variety of unlikely remedies for baldness, from donkey hooves in ancient Egypt to fresh air and exercise in Victorian England. A quick look online and the modern-day choices are just as bamboozling: scalp rollers, caffeine shampoo, laser combs, microneedling, to name a few. The latest trend is rosemary oil, with TikTok full of young men exhorting its powers. (Personally, I’m not minded to try it, on the basis that I don’t want to smell like a roast potato.) Some of these treatments may do limited good for some people, but there is little scientific evidence that they slow or reverse balding. Those that do can have side effects and don’t always work for everyone (see “Two drugs that help treat hair loss (well, a bit)” below).

Thierry Henry. By age 50, 30 to 50 per cent of men experience pattern baldness
CHRISTOPHE SAIDI/SIPA/Shutterstock
Determined to make sense of it all, I visited hair and scalp expert Hugh Rushton at his clinic on London’s Harley Street. He talked me through the basics of how hair loss works. First, you need to know that each hair goes through a growth cycle, growing for several years before taking a break for about three months and then falling out. About 10 to 15 per cent of hair is in this resting state at any one time. As male bodies age, healthy hairs can go through a process called miniaturisation, where they turn from regular “terminal hairs” into baby-fine “vellus hairs”, which are almost invisible.
What causes baldness?
We have known for a while that the hormone dihydrotestosterone (DHT), which stimulates the development of male characteristics, plays a key role in this process. DHT prompts follicles to miniaturise, and if you can reduce it, balding can be slowed. Over the past few years, though, researchers have made spectacular progress in understanding the complex biology surrounding hair growth and loss and the many biological components involved.
It was cell biologist Karl Koehler at Harvard University who made a pivotal breakthrough around a decade ago. Back then, he and his team were trying to grow a type of cell found in the inner ear using stem cells. However, it turns out that these ear cells are closely related to skin cells, and the researchers found that they always got some patches of skin growing as a side product. At first, this was a pain. “It was this weed in our garden that we were trying to get rid of,” says Koehler. Then they realised that these fragments of skin, if left to grow, would form two layers – the dermis and epidermis – and, eventually, even hair follicles. They had inadvertently created a skin organoid, with all its attendant parts.
Koehler and his team refocused their efforts on culturing skin, tweaking the chemical recipe they fed the cells to steer them into the optimal pathway. In 2018, they published a paper demonstrating their success developing mouse skin, and in 2020, they repeated the feat with human skin.
It takes about 50 to 70 days to culture a stem cell into a small patch of skin with hair. The skin forms in a bulb-like shape, about 4 millimetres wide. Koehler says he has already grafted these bulbs onto the backs of mice, where the skin begins to grow hairs. The first application could be as a way to test drugs to treat skin conditions, he says. But it is tempting to wonder whether this could be a way of grafting hair onto a bald head.
Hair transplants already exist, of course, but they have drawbacks. Follicular unit extraction, or FUE, for instance, takes follicles from the sides and back of the head, where the hair is still growing, and transplants them onto a balding area. The trouble with FUE, aside from the cost, is that it merely redistributes hair so cannot transform an empty scalp into a luxuriant mane.
A cure for baldness
With Koehler’s hairy skin organoids, we are talking about growing new hairs, which is quite the breakthrough. You could easily imagine it being used to reverse baldness. “We’re definitely thinking about this,” says Koehler. There will, however, be hurdles, like growing the skin larger and overcoming graft rejection – the skin would probably have to be grown from stem cells taken from the transplant recipient. “It’s going to be hugely expensive and not fast – not on the timescale some balding men might like,” says Koehler. But perhaps there is an easier option.
At the root of each hair there is a group of dermal papilla cells, which are involved in regulating hair growth. We know that in some hair follicles, such as those on the head, these crucial cells are lost with each successive hair growth cycle, until they are all gone. As a result, the signals telling hairs to grow cease and hairs miniaturise. So why not replace dermal papilla cells? That is what Colin Jahoda at Durham University, UK, thought several decades ago. He took these cells from the coat hair of mice and injected them into the rodents’ ears, which have much finer hair. The ear hair quickly grew longer and thicker.
In the early 2000s, regenerative medicine entrepreneur Paul Kemp founded a company that investigated whether injection of dermal papilla cells into the human scalp could stimulate the growth of entirely new hairs. The researchers found that it worked, but the new hairs were thin. However, at the same time, they observed that thinning hairs got thicker. The treatment went through stage I and II clinical trials, which showed that it was safe. But then for reasons that are unclear, the line of research was dropped.

A hair follicle expressing proteins (red) that help it grow. These proteins could be used to help stimulate new growth
Jiyoon Lee and Karl R. Koehler
In 2015, Kemp founded HairClone to revive the work on dermal papilla cells. The plan was twofold. First, healthy dermal papilla cells would be extracted from young people and frozen in a follicle bank. Then, when those people began to thin on top, the cells would be cultured and injected back into the scalp. “The idea is that, as those cells are being lost, you’re injecting them back in,” says HairClone’s head of research, Jennifer Dillon. Unlike the skin organoids, this treatment doesn’t have the potential to restore hair to a person in an advanced stage of pattern baldness because it would only revive ageing follicles, not those that have already miniaturised. But it is a big deal because it could fix the problem of follicles dying off in the first place.
Follicle banking
HairClone has already created a follicle banking service, where people can have some of their dermal papilla cells removed and cryogenically frozen. This service is available in the US, Canada, Australia and the UK. Meanwhile, Dillon is working on perfecting the process of multiplication.
Dillon says the procedure is popular among parents who want to bank their teenage sons’ follicles, so that they may avoid the hair loss their fathers have experienced. But women are banking too. Jane (not her real name) from London experienced hair thinning after an infection in 2018 and later discovered that she had breast cancer. With the prospect of losing the rest due to chemotherapy, she decided to take out an “insurance policy” and bank 100 of her follicles. “I would be gutted if they invented some way to rejuvenate hair and I had not taken the opportunity to prepare for it,” she says. The banking cost £2000 and she pays a yearly fee of £120 to keep her follicles on ice.
The next step is to show that the injection of cultured dermal papilla cells is safe and effective. HairClone is currently offering the treatment off label in the UK. The company can’t make any claims about its efficacy, but can give it to people to collect data about the best treatment regimen ahead of clinical trials.
Maria Kasper, who studies the biology of skin and hair at the Karolinska Institute in Stockholm, Sweden, says she hasn’t seen enough data to judge how efficiently it will work in balding human scalps. She also points out that each round of cloning tends to reduce the papilla cells’ ability to induce hair growth, which could be a challenge. “But when it works,” she says, “it would likely be a long-term solution”, with the revitalised hair perhaps lasting decades.
The secret of hair growth
Dermal papilla cells offer great promise, but perhaps we don’t need to go to the trouble of growing them. Maybe we can replicate the chemical signals they whisper to hair instead. To do so, we need to know the nitty-gritty details of exactly what makes hair grow. “That is what the last decade and a half has provided,” says Plikus.
All over the skin, there are epithelial stem cells that can go on to form other kinds of cell, including hair cells, depending on the chemical signals they receive. In theory, if you could hijack this cell signalling, you might produce a hair loss therapy. This is a fraught business, though. Two of the pathways known to enhance hair growth are called Wnt and hedgehog, so one idea would be to dial their activity up. However, their activity is also increased in many cancers.
You can think of these signalling pathways as a bit like a row of dominoes that splits off in many directions. Push over the first domino and you set off a messy, unstoppable chain reaction that might cause cancer. But Plikus reasoned that it might be possible to set off the reaction much further down the line, where the effects are more controllable.
He and his team began exploring this by genetically engineering mice in different ways so that their hedgehog signalling pathways were dialled up. One particular mouse looked promising, growing more hair than the others. By comparing all of the signalling molecules involved with those from non-engineered mice, they identified a protein called SCUBE3 that was boosted at a late stage in the hedgehog pathway. Investigations showed that this molecule is also switched on in human hair follicles at the start of a growth cycle.
Balding vaccine
Plikus says you could imagine SCUBE3 being injected into the scalp, or perhaps being administered as an mRNA therapy, where cells are given the instructions to make the protein, similar to how some covid-19 vaccines work. The first thing is to understand whether SCUBE3 would be safe as a drug. A spin-off company called Amplifica has now begun early-stage clinical trials to establish this.
But Plikus isn’t done there. He has already produced another potential drug candidate, based on the bizarre fact that skin moles often encourage vellus hairs to turn thick and long. Perhaps, he thought, he could divine their secrets and use them to reverse baldness.
In June, he and his colleagues published work showing that a molecule called osteopontin was an important signal that drives the growth of these thick hairs in moles. “What’s particularly exciting with this molecule is that nature has performed a natural experiment for us,” says Plikus. Hairy moles appear on people with a wide variety of genetic make-ups, so we know that the effects of osteopontin aren’t likely to be limited to a small group of people.
But the reason for optimism in this field isn’t about any one treatment. Rather, it is that our burgeoning understanding of the signals that drive hair growth and loss suggests that there will be many ways of intervening in the process. That increases the odds of finding one strategy that works.
In my stronger moments, I tell myself I should shave all my hair off and be done with it – or just stop worrying about it. Then again, there is a wider perspective on all this. Most mammals have hair all over their bodies, but we humans lost the majority of ours aeons ago. In that context, maybe I can console myself with the notion that the hair on our heads is really just a remnant of a bygone age.
Male pattern baldness happens when an enzyme called dihydrotestosterone (DHT) prompts hair follicles to give up the ghost (see main story). Finasteride, sold as Propecia, among other names, is a medicine that stops one of the body’s ways of converting testosterone into DHT. It is most effective when taken in the early stages of balding. However, it has some side effects and only works for as long as it is being taken. It isn’t effective for everybody, not least because the body has other ways of making DHT that can, for reasons not well understood, kick in for some people and not others. Finasteride can’t be used to treat female pattern baldness.
Then there is minoxidil, sold as Rogaine, among other names. Exactly how it works isn’t clear, but it is thought that it extends the natural hair growth cycle in men and women, so that you have more hairs growing on your head at any one time. Again, the results last only as long as the product is used and they can peak after a few months and then decline.
Joshua Howgego is a features editor at New Scientist