health & science

What human hair and zombies have in common

Here in New Zealand our Crown agency scientists are mostly interested in studying wool - but in the process they've helped unravel the strange science of human hair, reports Eloise Gibson.

There’s a point about four millimetres inside your scalp where your hair cells become zombies.

These ravenous entities throw away their ‘brains’, or nuclei, and become automatons with only one purpose - devouring as much protein as possible as they sleepwalk towards certain death.

That, more or less, is what a team of scientists, including a New Zealander, found when they studied human scalp biopsies – small chunks of hair and skin taken from volunteers undergoing plastic surgery and examined with powerful microscopes.

The study, which won attention in hair science circles, was aimed at understanding how hair goes from being composed of living cells, to zombie cells (cells that have thrown away their nuclei so they’ll have maximum space to pack in keratin, or the fibres that make hair strong) to, finally, the dead matter attached to our heads that we try to tame each morning.

Most people probably know that hair, no matter how glossy, is technically dead once it’s outside the body.

But pin-pointing where the change from living to dead happens may help doctors and cosmetic companies design better products and treatments for hair loss, greying and other hair-related issues, says Duane Harland, a scientist from AgResearch who helped lead the research.

Right now, unscrupulous marketers can more or less rely on the fact that no one really understands what happens inside the hair when it’s going from a living, biological entity to a bunch of brain-dead cells that are governed by purely chemical processes, he says. That makes it hard to prove companies are making baseless claims about products - even when they probably are.

“It’s very hit and miss, some products have had an enormous amount of research put into them to prove they work, this is typical of the big companies,” says Harland. “On the other hand, there’s a lot of less-than-quality research out there and a lot of claims that are pretty much baseless. And a lot of stuff that will work, but not necessarily for the reason they are selling it - so if you have badly damaged hair, for example, because the hair has been repeatedly bleached and straightened and dyed … and it gets cracked, it gets its proteins removed … and if you start putting materials into those cracks, yeah, it sticks it in place it will work but … there are a lot of people out there selling stuff and just hoping, without having done any of the work.”

“The hair that’s growing outside our body is a material that’s totally dead, it’s a lightweight armour that our body has produced."

“The fact we don’t know enough about the way in which the biology and the chemistry works has really been a huge advantage to snake oil salesmen over the years because they can make claims knowing full well that not enough is known to be able to say they’re wrong,” says Harland.

Legitimate hair research is potentially big business, however, which is why several large companies invest in it.

The latest study was a joint effort sponsored by the cosmetic giant Procter and Gamble and largely carried out by a researcher, Leigh Ann Jones, working at the Institute of Medical Cell Biology at Singapore's Agency for Science Technology and Research (A*STAR). New Zealand’s AgResearch contributed the electron microscopy of the plucked hairs to complement the fluorescent light microscopy carried out at A*STAR. Harland helped analyse the data; while AgResearch’s interest is finding ways to get sheep to grow better wool, there's a lot of cross-species research in the hair world, because all mammals have similar hair.

The study was described in a plain language summary translating the original paper from the British Journal of Dermatology. As the translation explains, the building blocks of hair begin life as active cells busily moving, dividing and making all sorts of molecules in order to stay alive. However, to turn into tough healthy “hair” they need to pack themselves full of fibres known as keratin – hence why so many hair care treatments trade on the word "keratin".

To make space for keratin, the cell must have a spring clean and throw away all of its contents including its brain (nucleus) and lungs (mitochondria), a somewhat mysterious process that scientist have likened to becoming the walking dead. “The hair that’s growing outside our body is a material that’s totally dead, it’s a lightweight armour that our body has produced," says Harland. “Basically cells sacrifice themselves to become this dead material. [But] exactly how that happens and how the process is influenced by, not just genetic signals, but things like the metabolic environment has received a lot less attention than it should have.”

"They are plodding onwards and upwards, slowly disintegrating in a programmed way… the wheel is still spinning but the hamster's dead."

For the study samples of hair follicles (hair plus surrounding scalp) were taken from healthy volunteers in a process much like coring an apple, the summary explains. These samples were then stained using chemicals and looked at using a very powerful microscope, which allowed the scientists to see the spring cleaning process happening in an organised way, all within the first 1mm of hair follicle. 

The summary describes what happens in this action-packed 1mm: “First the cells threw away their nucleus, or “brain”, meaning that they could no longer make decisions, much like a zombie. However, these cells could continue to “breathe” as they still had their mitochondria, or “lungs”. These zombie cells had one singular role which was to fill themselves full of keratin, throwing away their “lungs” at the last minute, when no further space remained. This discovery is not only interesting but informs hair scientists to target the first 1mm of the hair follicle when developing treatments to prevent hair thinning, greying and hair loss," it says.

Pin-pointing the exact spot where happens was important to understanding how hair forms and how we can make it healthy, says Harland.

If you want to see the approximate point of zombification for yourself, pluck a hair from your head and look at it – the thicker part at the base is part of what's call the bulb and you probably snapped it in half when you removed the hair. (Don’t worry, the hair follicle will probably re-grow).

You won't be able to see it, but inside your scalp at the bottom of the bulb is where your hair cells first divide in the follicle – the start of the process of growing new hair. In the beginning, these cells are very much alive. “When you look at these cells with a powerful electro-microscope you can see the cell structure and the nucleus everything looks totally normal, you wouldn’t pick it as any different to any other living cell," says Harland. But right from conception these cells are programmed for death. “They start migrating upwards and it's almost like a car factory … there’s hundreds of cells at any one point that are moving upwards and being changed as the keratin inside them is being assembled, and then they discard the bits they don’t need and then they harden," he says. “By the top of the bulb the nucleus has been knocked out.”

During the ‘zombie’ phase the cells have “a lot of active chemical and biochemical processes going on, but the brain is dead … at that point, if something happens they can’t react by producing a new set of proteins … they’ve lost that ability to be flexible in how the cell responds.” The zombie cells keep heading up towards the outside of your scalp. "They are plodding onwards and upwards, slowly disintegrating in a programmed way… the wheel is still spinning but the hamster's dead," says Harland.

“At that point they are no longer really alive anymore, but they are not quite completely inert, they have got forward momentum and there is keratin being assembled and there are enzymes working to do particular jobs.” Then the cell throws away its final piece of baggage – the mitochondria, or as the researchers call them, the lungs. Now you have a truly dead cell that will hang around, outside your body keeping your head warm for several years, unless you cut it off.

As with everything that gets discovered in science – including stars, sea creatures and new diseases – this crucial spot inside the hair follicle is going to need a name.

Harland and his collaborators are hoping to name it “Orwin’s Threshold” after a New Zealand wool and hair scientist, Don Orwin, who died in 1989.

“He spent about 30 years working on wool follicles and wool fibres at the Wool Research Organisation out here at Lincoln,” says Harland.

Since there is no official naming committee for hair follicles, these things tend to happen by convention and being used in published research and science gatherings, says Harland.

He and his colleagues have already introduced the term at a big hair science conference – now they just have to hope it sticks. If it doesn't, they could attempt to use the 'line of Zombification'. 

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