Last year, in a lab in Japan, a mouse grew hair.
That may not sound like much of an accomplishment for a mouse, but it was an extraordinary feat for the scientists watching it. For the first time, skin grown in a lab and then transplanted onto a mouse was doing all the things skin is needed to do — produce sweat, secrete protective oils, grow hair.
In a study published in the journal Science Advances, scientists from Japan’s RIKEN Center for Developmental Biology detail how they were able to craft fully functional skin from stem cells made from the gums of mice. When transplanted onto mice with suppressed immune systems, the skin integrated well and even made connections with surrounding nerve and muscle tissue.
Though they’re a good five to 10 years away from replicating the same technique in humans, the scientists say it has the potential to revolutionize skin grafts, which currently rely on skin taken from other parts of the body or still-flawed artificial skin. The former poses medical challenges, and the latter lacks the ability to grow hair or produce oils like normal skin — which, at best, makes the grafts look different from the rest of the body, and at worst can be a health hazard.
“We are coming ever closer to the dream of being able to recreate actual organs in the lab for transplantation,” lead author Takashi Tsuji said in a statement.
The project took advantage of a technique discovered in 2006 that allows researchers to genetically reprogram any old cell and turn it into a stem cell (technically known as an “induced pluripotent stem cell“). This meant that cells taken from the mice’s gums could then be guided down a different developmental pathway using a chemical signal. When transplanted onto other mice, the skin developed normally to form the various layers of skin responsible for the organ’s diverse functions.
That’s vital, because skin is more than just the packaging that keeps our innards from hanging out all over the place. The body’s largest organ is a thermostat, a producer of vitamins and lubricant, an energy warehouse and a bulwark against infection, not to mention one of our best sources of information about the world around us.
Many of those functions are eliminated in the current skin transplant process. The grafted skin can’t regulate temperature as well, since it doesn’t have the ability to produce sweat (which cools the body as it dries). Grafted skin also lacks sebaceous glands — many patients have to oil their skin constantly to keep it from drying out. And if the grafted skin doesn’t link up with muscle and nerve cells, one of our most sensitive sensory organs is rendered inert.
The researchers didn’t test whether the skin would work in mice without suppressed immune systems, and New York University dermatology chair Seth Orlow noted to U.S. News and World Report that the process the Japanese researchers used to develop the cells may be too “laborious” to be feasible for significant human transplants.
But John McGrath, a professor of molecular dermatology at King’s College London, told the BBC that researchers in his field had been waiting for this kind of study.
“It’s recapitulating normal skin architecture,” he said. “So rather than having isolated bits of skin [that don’t serve every function] … here we’ve actually got a whole box of stuff.”
If it works for humans, lab-grown skin developed by Tsuji and his colleagues has the potential to help burn victims and people who suffer from some forms of hair loss and other medical conditions, Orlow told U.S. News and World Report.
Beyond that, he added, “research like this is important because it is one step in a long journey of steps to eventual extraordinary therapies that lie ahead.”