Washington :Scientists have 3D printed ear, bone and muscle structures that matured into functional tissue and developed a system of blood vessels when implanted in animals.
Using a sophisticated, custom-designed 3D printer, scientists proved that it is feasible to print living tissue structures to replace injured or diseased tissue in patients.
The structures have the right size, strength and function for use in humans, researchers said.
“This novel tissue and organ printer is an important advance in our quest to make replacement tissue for patients,” said study senior author Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine (WFIRM) in US.
“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,” Atala said.
The Integrated Tissue and Organ Printing System (ITOP), developed by scientists at WFIRM, deposits bio-degradable, plastic-like materials to form the tissue “shape” and water-based gels that contain the cells.
In addition, a strong, temporary outer structure is formed. The printing process does not harm the cells.
Researchers optimised the water-based “ink” that holds the cells so that it promotes cell health and growth. 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 live while they develop a system of blood vessels.
“Our results indicate that the bio-ink combination we used, combined with the micro-channels, provides the right environment to keep the cells alive and to support cell and tissue growth,” said Atala.
The ITOP system is also able to use data from CT and MRI scans to “tailor-make” tissue for patients.
Several proof-of-concept experiments demonstrated the capabilities of ITOP. To show that ITOP can generate complex 3D structures, printed, human-sized external ears were implanted under the skin of mice.
Two months later, the shape of the implanted ear was well-maintained and cartilage tissue and blood vessels had formed, researchers said.
Printed muscle tissue was implanted in rats to demonstrate the ITOP can generate organised soft tissue structures.
After two weeks, tests confirmed that the muscle was robust enough to maintain its structural characteristics, become vascularised and induce nerve formation.
Jaw bone fragments were printed using human stem cells. The fragments were the size and shape needed for facial reconstruction in humans.
The researchers also printed segments of skull bone and implanted them in rats. After five months, the bioprinted structures had formed vascularised bone tissue.
The study was published in the journal Nature Biotechnology.