Materials
Liver tissue 3D printed by a team at Wake Forest Institute For Regenerative Medicine. The team designed a gel-like scaffold that kept liver cells alive for 30 days and won fi rst place in the 2021 NASA Vascular Tissue Challenge.
lung disease and haemophilia. “We are pursuing multiple strategies, including 3D printing, to move our projects forward to meet our ultimate goal – making patients better,” he adds. In fact, in 2021, the WFIRM fielded two teams in NASA’s Vascular Tissue Challenge and took first and second place.
fiction. Especially materials such as Polyethylene glycol (PEG), a polyether compound derived from petroleum, that is helping scientists push the boundaries of regenerative medicine and 3D tissue printing in a newer class of additive manufacturing known as ‘bioprinting’. This method of 3D printing involves a mixture of living cells and biomaterials, or bioinks, used to create organ-like structures that allow patients’ cells to multiply and is part of the growing field of regenerative medicine. PEG is one of the materials used because it mimics our cells’ physical and biochemical characteristics.
“We have printed bone, cartilage, and muscle tissue that, when implanted in experimental models, developed a system of nerves and blood vessels.”
Professor Anthony Atala
Professor Anthony Atala is director of Wake Forest Institute for Regenerative Medicine (WFIRM) in the USA, and his team developed the Integrated Tissue and Organ Printing (ITOP) System after starting out engineering tissues in the lab by hand. He was inspired to research the possibility of providing replacement tissues and organs after working as a paediatric urologic surgeon. “It’s devastating to both the patient and doctor when a patient needs replacement tissue for reconstruction and there is not a good option,” he says. “There is generally a Plan B, such as taking tissue from other organs, but it is almost never ideal.” Atala’s team have already implanted several tissues and organs in patients, such as skin, urethras, cartilage, bladders, muscle and vaginal organs – all created by hand. Their next goal is to be able to do the same using bioprinting. “This will allow us to automate the process and scale up the technology so it can be applied to many more patients,” he says. “We are working on developing replacement organs and tissues, as well as healing cell therapies, for more than 40 different areas of the body.” Projects range from blood vessels and kidneys to cell therapies for
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In terms of the best biomaterials for 3D printing, Professor Atala says researchers have developed various biomaterial systems that improve cellular interactions by providing appropriate environmental cues. These biomaterial systems consist of drug/ protein delivery systems, nano and micro-scale topographical features and hybrid materials that can actively participate in functional tissue regeneration. “Automated 3D bioprinting technology can manufacture complex, multi-cellular living tissue constructs that mimic the structure of native tissues,” he explains. “This can be accomplished by optimising the formulation of biomaterials to serve as the scaffolding for 3D bioprinting, and by providing the biological environment needed for the successful delivery of cells and biomaterials to discrete locations within the 3D structure.”
The first step in printing an organ or tissue structure for a patient is to expand the number of a patient’s cells in the laboratory to obtain the millions required to engineer replacement tissue. The printer has small nozzles to precisely deposit both bio- degradable, plastic-like materials to form the tissue ‘shape’, and water-based gels that contain the cells. This water-based ‘ink’ – cells and the materials that form the shape – is optimised to promote cell health and growth. In addition, a lattice of micro-channels is printed throughout the structure to allow nutrients and oxygen from the body to diffuse into the structures. This last process keeps the cells alive while the tissues develop their own system of blood vessels. “The system deposits both biodegradable, 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,” said Atala. “We have printed bone, cartilage, and muscle tissue that, when implanted in experimental models, developed a system of nerves and blood vessels. We showed that these structures have the correct size, strength and function for use in humans, proving the feasibility of printing living tissue structures to replace injured or diseased tissue in patients.” Advancements in biomaterials science and the field of additive manufacturing are promising for multiple areas of medicine, and Atala is optimistic about what the future holds. He concludes: “We’re excited and encouraged by the ability of regenerative medicine to provide replacement tissue made from a patient’s own cells, and what that can mean for their recovery and long- term health.” ●
Medical Device Developments /
www.nsmedicaldevices.com
Wake Forest Institute For Regenerative Medicine
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