Scientists grow a kidney in a lab.

There are around 100 thousand people in the US who are waiting for a kidney transplant, making kidneys the most in demand organ.

They have long waiting lists for future kidney transplants, because only about 18 thousand transplants are performed each year.

But now scientists have created a kidney grown in the lab, and they are hoping that their research will help people in need of a transplant in the future.

Researchers from the Massachusetts General Hospital have engineered a kidney using cells taken from a baby rat and transplanted into a rat's body.

Although it doesn’t function as well as a natural kidney, the lab grown kidney is the most complex organ to be bioengineered in a lab.

Other organs and artificial body parts have also been created in laboratory settings. For instance, scientists have created a human ear using a three dimensional printer. They made the ear using living cow ear cells and collagen that were injected into an ear shaped mold. The scientists then grew the ear shaped mold on the back of a rat for one to three months.