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It’s Alive! Wake Forest Bioprints Living Ear, Bone, Muscle


hey said they’d do it and now they have. In the cover story of SME’s Medical Manufacturing 2015 yearbook, Anthony Atala and James Yoo of Wake Forest Institute for Regenerative Medicine (WFIRM; Winston-Salem, NC) described the process by which they hoped to bioprint living- tissue structures with a custom-designed 3D printer (http:// tinyurl.com/ME-WFIRM). And now they have proven that their approach works—that it is feasible to print living tissue struc- tures to replace injured or diseased tissue in patients.


patients,” said Atala, director of WFIRM 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.” The precision of 3D printing makes it a promising method


for replicating the body’s complex tissues and organs. How- ever, current printers based on jetting, extrusion and laser- induced forward transfer cannot produce structures with suffi cient size or strength to implant in the body. The Integrated Tis- sue and Organ Printing System (ITOP), developed over a 10-year period by scientists at WFIRM, over- comes these challenges. The system deposits both biodegradable, plastic-like materials to form the tis- sue “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.


Human-sized external ears were printed and implanted under the skin of mice. Two months later, cartilage tissue and blood vessels had formed.


Reporting in Nature Biotechnology in February, Atala and Yoo (with co-authors Hyun-Wook Kang, Sang Jin Lee, and Carlos Kengla), said they have printed ear, bone and muscle structures: When implanted in animals, the structures matured into func- tional tissue and developed a system of blood vessels. Most importantly, these early results indicate that the structures have the right size, strength and function for use in humans. “This novel tissue and organ printer is an important advance in our quest to make replacement tissue for


A major challenge of tis- sue engineering is ensuring that implanted structures


live long enough to integrate with the body. The Wake Forest Baptist scientists addressed this in two ways. They optimized the water-based “ink” that holds the cells so that it promotes cell health and growth and they printed a lattice of micro-chan- nels 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. It has been previously shown that tissue structures with- out ready-made blood vessels must be smaller than 200 µm


April 2016 | AdvancedManufacturing.org 33


Photo courtesy WFIRM


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