Hearing by design: A report on new ways to build outer ears for people without them

Image courtesy: Klaus D. Peter, Wiehl, Germany
Image courtesy: Klaus D. Peter, Wiehl, Germany

By Tom Parker

Most people are used to seeing someone wearing custom earplugs or hearing aids, but only rarely do you see someone with no ears at all. This condition can be the result of an accident, but just as often people are born without outer ears, i.e., the exterior part of the ear known as the pinna. Apart from the physical handicap this causes the psychological effects can also be hugely damaging.

This is where surgeons like Dr. Arturo Bonilla, MD, of Microtia.net come in, physically sculpting these patients’ new ears from their own rib cartilage. This highly specialized technique has been around for more than 30 years and is still viewed as the “gold standard” for ear reconstruction.

That being said, researchers around the world have been working on alternatives with some success. A group of scientists at Cornell University recently created a lifelike human ear using 3D printing. Meanwhile, Thomas Cervantes and his team from Massachusetts General Hospital have successfully made an ear by growing cartilage in a lab.

Here is a look at these techniques–both new and old–and how they’re offering patients hearing by design.

 

AN EAR FROM A RIB

The oldest and most widely recognized procedure for ear reconstruction is to use the cartilage from a patient’s ribs to literally build a new ear. Microtia.net lists a number of reasons for this:

 

Ears consist of cartilage, so reconstructing them with cartilage makes a lot of sense. Also, using a person’s own cartilage greatly reduces the risk of infection or rejection by the body. Another advantage of using a patient’s own cartilage is that the ear will grow as the patient does.

 

For children born without ears the surgery is not generally performed until around or after age 6. This is mainly because the child’s ribs have to grow big enough to provide sufficient cartilage for the procedure. Normally three surgeries over 4 to 5 months are needed to complete the process.

 

 

LIVING INK

Lawrence Bonassar, a professor of biomedical engineering at Cornell University, and his team have developed a type of “ink” made up of living tissue. This “ink” is used in a 3D printer to create an ear that will have the ability to develop and remodel itself.

 

In an interview with Public Radio International, explained the process to Public Radio International, Bonassar explained that his group elected to “print with cells already embedded in the ‘ink’ rather than embedding live cells into an ear that’s already been printed.” He added that the reason the process is possible is that cartilage needs so little in terms of blood supply, since it can get its nutrients from the blood in the tissue surrounding it.

 

“The challenge,” he said, “Is assembling them in the right configuration and implanting them under conditions that will allow them to be vascularized, grow blood vessels as quickly as possible.”

 

 

SHEEP CARTILAGE

In the meantime, Thomas Cervantes and his colleagues have been experimenting with sheep cartilage, wire, and a 3D printer. The results have yielded a flexible human ear, and the team is preparing to undertake human trials soon.

 

The Daily Mail interviewed Cervantes and summarized the procedure as follows: A 3D model is printed using polydimethylsiloxane (a type of silicone) and filled with cow collagen. A wire structure is then embedded in the mold to add structure, after which sheep cartilage (which has been grown under the skins of lab rats) is used to replace the cow collagen.

 

Cervantes told the newspaper, “The technology is now under development for clinical trials, and thus we have scaled up and redesigned the prominent features of the scaffold to match the size of an adult human ear and to preserve the esthetic appearance after implantation.”

The benefits of these 3D ears, should they pass muster during human trials, are that they’ll be produced quickly and won’t require cartilage from patients. This means patients will need less surgery and, thus, face less risk.

In the meantime, it seems that the tried and tested technique of using a patient’s cartilage for ear reconstruction remains the best option.

 

Tom Parker is Managing Director at PC Werth, a UK leader in Education Communication for over 20 years. PC Werth subsidiaries include PerfectFitEars and LaceUK.