Scientists say they’ve built a facsimile of a living human ear that looks and acts like a natural ear. The team from Weill Cornell Medical College and Cornell University believe their bioengineering method can provide normal looking “new” ears to thousands of children born with a congenital ear deformity, or individuals who have lost part or all of their external ear in an accident or from cancer.
The researchers used 3D printing and new injectable gels made of living cells to fashion ears that are identical to a human ear. Over a three-month period, these flexible ears steadily grew cartilage to replace the collagen that was used to help mold them.
This Cornell bioengineered ear is the best to date in appearing and acting like a natural ear, the researchers report. Also, the process of making the ears takes a week at most, they claim.
The deformity the researchers seek to remedy is microtia, a congenital deformity in which the external ear is not fully developed. To make the ears, the researchers first took a combination laser scan and panoramic photo of an ear from twin girls, which provided a digitized 3D image of their ears on a computer screen. The researchers then converted that image into a digitized “solid” ear and used a 3D printer to assemble a mold of the ear. The mold is like a box with a hole in the middle that is in the shape of the mirror image of the ear, say researchers.
They injected animal-derived collagen into that ear mold, and then added nearly 250 million cartilage cells. The collagen served as a scaffold upon which cartilage could grow. This high-density collagen gel, which Cornell researchers developed, resembles the consistency of flexible Jell-O when the mold is removed.
“The process is fast,” says one of the study’s lead authors, Lawrence J. Bonassar, Ph.D., associate professor and associate chair of the department of biomedical engineering at Cornell. “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 a nourishing cell culture medium before it is implanted.”
During the three-month observation period, the cartilage in the ears grew to replace the collagen scaffold. “Eventually the bioengineered ear contains only auricular cartilage, just like a real ear,” adds co-lead author Jason Spector, M.D., director of the Laboratory for Bioregenerative Medicine and Surgery (LBMS) and associate professor of surgery of plastic surgery in the Department of Surgery at Weill Cornell Medical College and an adjunct associate professor in the Department of Biomedical Engineering at Cornell University.
Previous bioengineered ears have not been able to maintain their shape or dimensions over time, and the cells within them did not survive.
The researchers are now looking at ways to expand populations of human ear cartilage cells in the laboratory so that these cells can be used in the mold.
Dr. Spector says the best time to implant a bioengineered ear on a child would be when they are about 5- or 6-years-old, because at that age, ears are 80 percent of their adult size. “We don’t know yet if the bioengineered ears would continue to grow to their full size, but I suspect they will,” says Dr. Spector. “Surgery to attach the new ear would be straightforward: the malformed ear would be removed and the bioengineered ear would be inserted under a flap of skin at the site.”
Dr. Spector says that if all future safety and efficacy tests work out, it might be possible to try the first human implant of a Cornell bioengineered ear in as little as three years.
The study is published in PLOS ONE in an article titled “High-Fidelity Tissue Engineering of Patient-Specific Auricles for Reconstruction of Pediatric Microtia and Other Auricular Deformities”.