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, Bonassar and colleagues started with a digitized 3D image of a human subject?s ear and converted the image into a digitized ?solid? ear using a 3D printer to assemble a mold.
They injected the mold with collagen derived from rat tails, and then added 250 million cartilage cells from the ears of cows. The high-density gel has a consistency that is similar to Jell-O when the mold is removed. The collagen serves as a scaffold upon which cartilage can 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,? Bonassar says. ?We trim the ear and then let it culture for several days in nourishing cell culture media before it is implanted.?
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?Using human cells, specifically those from the same patient, would reduce any possibility of rejection,? Spector says. He adds that the best time to implant a bioengineered ear on a child would be when they are about 5 or 6 years old. At that age, ears are 80 percent of their adult size.
If all future safety and efficacy tests work out, it might be possible to try the first human implant in as little as three years.