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 on to 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 Centre for Developmental Biology detail how they were able to craft fully functional skin from stem cells made from the gums of mice. When transplanted on to 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 revolutionise 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 reprogramme any old cell and turn it into a stem cell (technically known as an "induced pluripotent stem cell"). This meant cells taken from mice's gums could then be guided down a different developmental pathway using a chemical signal. When transplanted on to 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.