Bioengineers have used 3D printing to achieve a breakthrough in prosthesis by creating the first artificial ears that look and act like real ones.
A new study by researchers at Cornell University, New York, shows how prosthetic ears almost indistinguishable from natural ones can be 3D printed using gels made of living cells.
Not only that, but over a three-month period these flexible, artificial ears grew even their own cartilage to replace the collagen used to mould them.
‘This is such a win-win for both medicine and basic science, demonstrating what we can achieve when we work together,’ said study author Lawrence Bonassar, associate professor of biomedical engineering.
The novel ear may be the solution surgeons have long wished for to help children born with ear deformity, said co-author Dr Jason Spector, professor of plastic surgery at Weill Cornell Medical College.
‘A bioengineered ear replacement like this would also help individuals who have lost part or all of their external ear in an accident or from cancer,’ he said.
Currently, replacement ears are usually constructed with materials that have an unnatural Styrofoam-like consistency
Alternatively surgeons may sometimes build ears from a patient’s harvested rib, but this option is challenging and painful for children, and the ears rarely look natural or perform well, said Dr Spector.
To make the ears, Professor Bonassar and colleagues started with a digitised 3D image of a human subject’s ear.
They then used a 3D printer to assemble a mould based on the scan and poured in their ‘living’ collagen gel.
This Cornell-developed, high-density gel is similar to the consistency of jelly when the mould is removed. The collagen serves as a scaffold upon which cartilage could grow.
The process is also fast, Professor Bonassar added.
‘It takes half a day to design the mould, a day or so to print it, 30 minutes to inject the gel, and we can remove the ear 15 minutes later,’ he said.
‘We trim the ear and then let it culture for several days in nourishing cell culture media before it is implanted.’
The new process offers hope to thousands of children born with a congenital deformity called microtia.
The incidence of microtia, which is when the external ear is not fully developed, varies from almost 1 to more than 4 per 10,000 births each year.
Many children born with microtia have an intact inner ear, but experience hearing loss due to the missing external structure.
Dr Spector and Professor Bonassar have been collaborating on bioengineered human replacement parts since 2007.
Professor Bonassar has also worked with Weill Cornell neurological surgeon Dr Roger Härtl on bioengineered disc replacements using some of the same techniques.
The researchers specifically work on replacement human structures that are primarily made of cartilage – joints, trachea, spine, nose – because cartilage does not need to be vascularized with a blood supply in order to survive.
‘Using human cells, specifically those from the same patient, would reduce any possibility of rejection,’ Dr Spector said.
He added that the best time to implant a bioengineered ear on a child would be when they are about five or six years old. At that age, ears are 80 per cent of their adult size.
If all safety and efficacy trials prove successful, it might be possible to try the first human implant of a Cornell bioengineered ear in as little as three years, Dr Spector said.