Viable treatment options for children born with microtia, a congenital deformity of the outer ear, may finally exist in the form of 3D-printing — and it really is almost as simple as printing a new ear.The process is detailed in a paper that was published in PLOS One on Wednesday, Feb. 20.
Current solutions involve shaping the ear's shell with a styrofoam-like material, which could extrude painfully from the skin once implanted and which rarely looks realistic. Patients can also undergo two lengthy and painful operations in which doctors take cartilage from the ribs, shape it and then implant it. Inner ear function is not affected with microtia, but because of missing or damaged parts of the outer shell, hearing loss is still a problem.
Now, bioengineers and physicians at Cornell University are developing a new kind of treatment, which involves shaping a model, printing a mold based on the undamaged ear, then injecting it with a dense gel that will act as a scaffold for cartilage growth.
Right now, the treatment has only been tried with bovine cartilage, and the process is quick: "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," co-lead author Bonassar told ScienceDaily. The scientists would place the scaffold in a cell culture based on the patient's own cells (a cartilage sample from the microtic ear and bone marrow from elsewhere) for a few days, allowing cartilage to grow on the scaffold, and then it would be ready for implantation.
Scientists see the most potential in this approach because cartilage does not need an immediate supply of blood to grow and survive. The hydrogel is enough for stem cells to lay down a cartilage matrix.
Microtia affects four in 10,000 children. Jason Spector, director of the Laboratory for Bioregenerative Medicine and Surgery at Weill Cornell Medical College, said that the best time to implant the ear would be when the child is about 5 or 6 years old; by that time, ears are 80 percent of their adult size and even if it failed to grow to its full potential, would still be fairly proportional into adulthood.
Bonassar estimated that optimistically, this treatment would see widespread clinical trials in four or five years. Spector said that the first human implant could happen in as little as three.
