Scientists have built an artificial human ear by combining living tissues from cows and sheep and growing them around a flexible wire frame that retains the correct anatomical shape of the organ.
It is the latest development in 3D tissue engineering where substitute organs are made in the laboratory in the hope of using them to replace the damaged or missing body parts of patients.
The artificial ear is described as a “proof of concept” prototype, and further research and development will be needed before it could be used in clinical transplants on patients.
However, medical researchers hope that patients with missing or deformed outer ears, such as children suffering from a congenital deformity called microtia, might soon be offered living substitutes that could be permanently attached to their heads.
A key feature of the artificial ear is a cartilage scaffold with an embedded titanium wire which retains the shape of the structure as well as maintaining its flexibility, said the researchers from the Massachusetts General Hospital in Boston.
“The technology is now under development for clinical trials, and thus we have scaled-up and redesigned the prominent features of this scaffold to match the size of an adult human ear and to preserve the aesthetic appearance after implantation,” they said in the study, published in the Journal of the Royal Society Interface.
Collagen connective tissue from a cow was formed into the shape of a human pinna – the fleshy visible part of the ear – and held in place by titanium wire. The porous collagen was then “seeded” with ear cartilage cells taken from a sheep and the cells grew within the porous collagen fibres.
The scientists grew the ear on mice and rats lacking an immune system to show that it was possible for it to be connected to a blood supply without tissue rejection. In a human transplant, the ear would have to be either made from a patient’s own stem cells or used with anti-rejection drugs.
An important feature of the technology is that the ear can be designed to look as natural as possible by pulling the skin taut over the wire and cartilage frame using vacuum suction, the scientists said.
Earlier this year, scientists from Cornell University in New York made a similar artificial ear built from an injectable gel produced by 3D printing to mimic the precise shape of the real organ.
“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,” said Jason Spector, director of bioregenerative medicine at Cornell.
Other attempts at making bioengineered organs are well-advanced. About a dozen patients have already received transplants of artificial wind pipes made from a synthetic scaffold material coated with stem cells taken from either the patient or a donor.
The world’s first patient to receive an artificial windpipe was a 30-year-old Spanish woman called Claudia Costillo, who underwent the operation in 2008 with stem cells from a donor.
One of the latest patients to use their own stem cells was a 2-year-old girl, Hannah Warren, who died earlier this year of lung complications following a second operation, even though her transplanted windpipe was working well, according to her doctors.