Simpler forms of exterior soft tissue are among the first candidates for tissue engineering, and work continues on ways to produce tissue structures such as ears:
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.
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. "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."
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.