For the first time, scientists have used stem cells to grow an adult-size human ear on the back of a rat.

The scientists, who come from the University of Tokyo and Kyoto University, say the ear could be grown to repair faces disfigured in battle or accidents and also help people born without ears or with ear deformities.

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In the United States alone, a range of about 1 to 5 children out of 10,000 are born with misshapen or missing ears.

To grow the ear, the team induced pluripotent stem cells to grow into ear cartilage. Those cells were then placed into a kind of biological tubing shaped roughly as an ear.

The ear form was then implanted under the skin of a live rat and the cells were left to grow for about two months. Around that time, the tubes dissolved, leaving behind the human ear about 2 inches long.

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It’s not the first time researchers have grown an ear on the back of a rat.

Back in 2013, a team from Massachusetts General Hospital in Boston used bovine collagen and cells from sheep to grow an ear on a titanium wire frame shaped like the body part.

So-called tissue engineering is being explored to grow other kinds of body parts, too, including noses and windpipes.

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The Japanese researchers say because their ear is a living part, it would develop as a child grew.

They hope to start clinical trials in about five years.