In the beginning, there was the earmouse: naked, pink, and toting on its back a grotesque ear-like appendage the size of a child’s ear. When an image of this mouse-grown “ear”— actually a piece of cartilage taken from a cow’s knee and implanted into the rodent—circulated on the Internet, it shocked scientists and the public alike. But it also suggested the potential for tissue engineering to revolutionize the options for those who needed organs or body parts—in this case, an ear.
Unfortunately, science doesn’t always move in smooth leaps and bounds. And so, 20 years later, political and bureaucratic hurdles have meant that genetically engineered ears still aren’t commercially available in the U.S., where hundreds of thousands of people have suffered ear injuries due to gunshot wounds, cancer of the ear or microtia, a malformation of the external ear. (In China, the researchers who developed the earmouse are currently testing the technique of growing cartilage into ears on human patients.)
Now, a team of researchers from the U.S. and U.K. are aiming to change that. Inspired by the earmouse, doctors at the University of California at Los Angeles and the University of Edinburgh’s Centre for Regenerative Medicine have perfected a new technique to grow a fully formed human ear, using patients’ own stem cells. They begin with a 3D-printed polymer mold of an ear, which is then implanted with stem cells drawn from fat. As these stem cells differentiate into cartilage, the polymer scaffold degrades, leaving a full “ear” made of mature cartilage cells.
The new approach could “change all aspects of surgical care,” says Dr. Ken Stewart, one of the researchers and a plastic surgeon at the Royal Hospital for Sick Children.