When it comes to repairing human bodies, there’s one major difficulty: spare parts are hard to come by. It’s simply not possible to buy a knee joint or a new lung off the shelf.

At best, doctors and surgeons have made do with transplants from donors where possible. However, these are always in short supply, and come with a risk of rejection by the patient’s body.

If we could 3D print new custom body par/ts to suit the individual, it would solve a lot of problems. A new ear implant pioneered by 3DBio Therapeutics has achieved just that.

Grown To Order

The implant is known as the AuriNovo, so named to evoke a meaning of “new ear.” It’s designed to treat a condition known as microtia, in which the external ear structure is underdeveloped on one or both sides. Each year, roughly 1,500 babies are born with the condition in the United States.

Current treatments involve taking a sample of cartilage from the ribs from the patient and manually carving it to resemble a typical ear shape. This can then be implanted with a low likelihood of rejection as it’s made from the patient’s own cells. Alternatively, implants can be made from synthetic materials, and placed under the skin.

The AuriNovo ear goes the biological route, but negates the need to harvest a large amount of cartilage from the ribs. Instead, in the pioneering surgery, just half a gram of cartilage was taken as a biopsy from the patient’s existing ear structure. From there, special cells called chondrocytes were separated out. These cells, which are used for cartilage formation, were then cultivated in a proprietary nutrient solution to multiply in their billions.

From there, the chondrocytes grown from the patient’s sample were combined with a collagen-based “bio ink”. The resulting mixture was then used in a special 3D printer specifically built for creating biological structures. The ink and printer are both design specifically to keep everything sterile to reduce the chance of complications or rejection from the patient’s body. The printer created a replica of the patient’s fully-developed ear out of the biological material, albeit flipped to suit the opposite side of the head.

The ear was then given a special biodegradable overshell for support, and shipped via cold storage. Shortly after arrival, the printed structure was implantaed under the patient’s skin, which stretched around and took on the expected form of a fully-developed human ear. The overshell is intended to be absorbed by the body over time, leaving the printed cartilage structure behind.

It’s early days yet, and the clinical trial involving 11 patients is still ongoing. However, prospects for the technique are good. The resulting structure is made of biocompatible materials as well as cells grown from the patient themselves, making rejection unlikely. Plus, as the implant is made of living material, it should remain flexible and maintain the look and feel of a regular human ear over the long term.

Fundamentally, the external ear structures are relatively simple things. They’re largely scaffolding, though they do play a role in helping to capture sound coming into the ear. They also have the benefit of being made largely of a single simple material, without any complicated biochemistry, veins, or nerves.

Thus, ear reconstruction is perhaps a perfect starting point for creating new body parts from scratch. Lessons learned in this project could help scientists working on more complicated problems with more mechanical complexity. This could lead to creating new mating surfaces for joints, or better restorative treatments for those with injuries. Long term goals involve 3D printing entire organs, like kidneys and livers. However, there’s plenty more work to be done before we’re able to recreate functional organs, with all their fluid inlets and outlets and complicated chemical processing abilities.

Overall, the AudiNovo is a solid first step into a new future, where custom body parts can be printed up on demand. Here’s hoping that the clinical trial delivers great results for all patients involved, and that it heralds in further advances in the field.

Images of ear framework: 3D Bio Therapeutics