A new method of 3D printing can now produce human-sized bone, muscle, and cartilage templates that have survived when implanted into animals.
Researchers from Wake Forest University, North Carolina, have developed a pioneering 3D bio-printer that is capable of generating replacement tissue that’s strong enough to withstand transplantation.
The scientists report that they found a way to print bone, muscle, and cartilage tissue that allows blood to flow, and cells to stay alive. This development may lead to printing living tissues for implantation in patients.
The research team, led by Anthony Atala, have been developing this technique for almost 10 years. But, now they have been able to unveil the Integrated Tissue and Organ Printing System (ITOP).
After it has been refined and proven safe in humans, replacement parts could be made to order meeting the unique needs of each patient. The details of this breakthrough have been published in Nature Biotechnology.
Bio-printers work much the same way as conventional 3D printers, building structures layer by layer. However, instead of using plastics, resins, and metals, bio-printers use special biomaterials that closely resemble functional, living tissue.
However, existing bio-printers cannot produce tissues of the right size or strength. They are far too weak, and structurally unstable for surgical transplantation. Another limitation is that they also cannot print more delicate structures like blood vessels. Without ready-made blood vessels, the cells cannot be supplied with critical nutrients and oxygen.
The biggest challenge, researchers say, was creating channels that would become the veins and arteries, allowing blood to flow through tissues and cells to stay alive. Atala, director of the Institute for Regenerative Medicine, told STAT that this has been “the basic limitation of this field forever, up to this point.”
The ITOP system uses a bio-degradable plastic that forms the tissue’s shape with water-based gels, which contain cells, combined with a temporary outer structure that maintains the shape of the tissue being printed.
Instead of trying to generate a series of channels for blood to flow through, the researchers designed the bio-printer to leave a series of micro-channels that allows the nutrients and oxygen to flow through the growing tissue once it has been implanted, where it will develop a system of blood vessels on its own.
To prove the method, an ear-shaped piece of cartilage, a muscle, and a piece of jawbone were printed, and then implanted on mice. Over a period of a few weeks to five months, the researchers found that the tissues had vascularized, and had continued developing.
Atala told Gizmodo:
“We basically recreated capillaries, creating microchannels that acted like a capillary bed.
“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.”
The 3D-printed tissues seem to be the right size, strength, and function for use in humans. The researchers say the system can generate to human-scale, structurally stable tissues in virtually any shape.
“It is often frustrating for physicians to have patients receive a plastic or metal part during surgery knowing that the best replacement would have been the patient’s own tissue,” Atala told Reuters.
“The results of this study bring us closer to the reality of using 3D printing to repair defects using the patient’s own engineered tissue.”
Once proven to be safe and effective, the researchers can then start to think about human trials. However, Atala conceded that: “It’s still going to be a while — we still have to go through a lot of testing.”
Watch this report from wochit Tech on the discovery: