[Researchers] described how 3-D printing and injectable gels made of living cells can fashion ears that are practically identical to a human ear. Over a three-month period, these flexible ears grew cartilage to replace the collagen that was used to mold them. A bioengineered ear replacement like this [would] help individuals who have lost part or all of their external ear in an accident or from cancer. [Replacement ears] are usually constructed with materials that have a Styrofoam-like consistency, or sometimes, surgeons build ears from a patient's harvested rib. This option is challenging and painful for children, and the ears rarely look completely natural or perform well.
To make the ears, [researchers] started with a digitized 3-D image of a human subject's ear, and converted the image into a digitized "solid" ear using a 3-D printer to assemble a mold. [This] high-density gel is similar to the consistency of Jell-o when the mold is removed. The collagen served as a scaffold upon which cartilage could grow. The process is also fast: "it takes half a day to design the mold, a day or so to print it, 30 minutes to inject the gel, and we can remove the ear 15 minutes later. We trim the ear and then let it culture for several days in nourishing cell culture media before it is implanted."