A 3D printer that can print human flesh in order to replace injured or diseased tissue has been demonstrated by scientists at Wake Forest Baptist Medical Centre in North Carolina.
Ear, bone and muscle structures that were printed by the machine and implanted into animals have subsequently matured into functional tissue and developed a system of blood vessels.
Although 3D printing has been used for medical purposes in the past, such as 3D-printed hip replacements, these used materials, such as metal, that are more traditionally used for bone replacements rather than tissue.
However, the new 3D printer is capable of producing fleshy structures. Dubbed the Integrated Tissue and Organ Printing System, it has been in development for 10 years.
The system deposits both bio-degradable, plastic-like materials to form the tissue ‘shape’ and water-based gels that contain cells.
In addition, a strong, temporary outer structure is formed. The printing process does not harm the cells.
The team said that one of the major challenges of tissue engineering was ensuring that implanted structures live long enough to integrate with the body.
In order to achieve this, they optimised the water-based ‘ink’ that holds the cells so that it promotes cell health and growth and they printed a lattice of micro-channels throughout the structures.
These channels allow nutrients and oxygen from the body to diffuse into the structures and keep them alive while they develop a system of blood vessels.
The technology was shown to work after test structures were implanted in rats and the structure was maintained two months later with cartilage tissue and blood vessels forming.
Printed muscle tissue was also implanted and tests confirmed that the muscle was robust enough to maintain its structural characteristics, become vascularised and induce nerve formation.
Jaw bone fragments were also printed using human stem cells, which after five months performed similarly well in the bodies of the rats.
"This novel tissue and organ printer is an important advance in our quest to make replacement tissue for patients," said Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine and senior author on the study. "It can fabricate stable, human-scale tissue of any shape. With further development, this technology could potentially be used to print living tissue and organ structures for surgical implantation."
With funding from the Armed Forces Institute of Regenerative Medicine, a federally funded effort to apply regenerative medicine to battlefield injuries, Atala's team aims to implant bioprinted muscle, cartilage and bone in patients in the future.