Scientists have grown a perfectly compatible ear in a lab and grafted it onto a patient, in what they said was a world first in regenerative medicine. The groundbreaking technique saw them use the patient’s own ear cartilage cells to form a new one. Five children suffering from a condition known as microtia, in which the external ear is underdeveloped, have undergone the experimental surgery. Currently the widely used treatments for microtia include the use of silicone prosthetic ears, or rib-cartilage reconstruction, which has mixed results. The new technique involves taking a scan of the child’s unaffected ear, reversing the dimensions and 3D-printing a biodegradable mould punctuated with tiny holes. Cartilage cells taken from the recipient’s other, unaffected ear are then used to fill the holes while the new ear is still in the lab.