Researchers from NCSU and UNC Create a 3D Biomedical Fiber Printer

It’s been 10 weeks since the NFL 2019 season began and already dozens of players have suffered soft tissue injuries. Arizona Cardinals wide receiver Christian Kirk is recovering from an ankle sprain while T.Y. Hilton from the Indianapolis Colts re-aggravated a quadriceps strain he sustained earlier this year just five weeks into the season. But this is just one sport were injuries run high and the risk of re-injury is even greater, especially since many try to return too quickly to the field. Sprains, strains, and contusions, as well as tendinitis and bursitis, are common soft tissue injuries in most contact sports, like football, rugby, ice hockey, soccer and more. Australian experts suggest that soft tissue injuries are the most common injury in sport, and they should know better since Australian Rules football and soccer had the highest population-based age-standardized rates of injury hospitalization. Soft tissue includes muscles, tendons, ligaments, fascia, nerves, fibrous tissues, fat, blood vessels, and synovial membranes, so it’s not really just sports players that need attention. Anyone can suffer from soft-tissue injuries, and even with the appropriate treatment, they may require surgery.

Yet, the challenges behind creating soft tissue have advanced slower than expected, with scientists even looking to develop tissue in space, using microgravity to accelerate development. However, last July, a team of researchers found a potentially transformative opportunity: applying 3D printing and non-woven fiber manufacturing to create new tissues that can grow in the human body. The Forging Interdisciplinary Bio-inspired Engineered Regenerative Science (FIBERS) team of researchers at North Carolina State University (NCSU) and the University of North Carolina at Chapel Hill have been exploring 3D printing strategies to make tissues such as the meniscus and tendons. One of the most significant advances so far has been a 3D biomedical fiber printer used to create biocompatible scaffolds.

NCSU states that while a 3D printer can precisely reproduce the shapes and structures in an MRI image or a CT scan, traditional 3D printers may not appropriately capture features at the tiny scale that tissue engineering demands. The difference between traditional devices and the FIBERS advanced 3D printer is the way it forms fibers: in offering more variety in the size, shape, and orientation of the layers of fibers that form an object, matching the natural fibers they’re aiming to replace and regrow.

“With conventional 3D printing, that’s where you run into roadblocks. The feature sizes that you can make can be an order of magnitude too large,” said Rohan Shirwaiker, an NCSU associate professor of industrial and systems engineering.

The 3D printer was built with support from the Game-Changing Research Incentive Program (GRIP), a partnership of the NC State Office of Research and Innovation; RTI International; and the Kenan Institute for Engineering, Technology and Science. They have a patent pending on the features of the process and have also applied for a second patent on the specific fiber geometry they have been able to produce with the machine.

“What we learned on the GRIP machine we could never do on a big pilot machine easily,” said Benham Pourdeyhimi, executive director of the Nonwovens Institute and the principal investigator for the FIBERS project. “So for me there were a couple of ‘AHA!’ moments. ‘Wow, if I could do that on a larger scale, it opens up opportunities outside of this domain for other applications.’”

According to NCSU, two questions have led the team’s work: How can you manufacture tissues at several scales, from micro to nano, with speed and repeatability? And what should those scaffolds be made of? So the focus has been on creating scaffolds, which give both form and direction to tissue growth.

Pourdeyhimi suggested that a scaffold’s mission is fleeting and sensitive so that once implanted, it needs to carry the load, then spark and shape cell growth, recruit other cells from inside the body, and finally disappear when the new tissue is able to function alone. And it needs to do all that without disrupting any of the cells and systems around it.

“We’re learning how to process materials that we’ve never processed before,” Pourdeyhimi said. “We’ve learned how to manipulate them and use more biofriendly types of polymers that the industry would need to use.”

NCSU informed that in order to meet the challenges facing tissue engineering, the FIBERS team had to draw knowledge and expertise from biomedical and industrial engineering, textiles and veterinary medicine. Department of Biomedical Engineering (BME) assistant professor Matt Fisher’s long-standing work on 3D printing tissues fits right in with the FIBERS initiative. Together with Shirwaiker, they were then invited to form the core team for the FIBERS project by BME Professor Frances Ligler and Pourdeyhimi.

Ligler claims that today, most transplanted tissues come from cadavers or the patients themselves, and there has been progress on using stem cells to repair damaged tissues, but neither approach delivers the level of customization that the human body demands.

So far, the research team’s work has focused on innovations that would improve the quality of life for the hundreds of thousands of people who get replacement soft tissues each year. Also, FIBERS investigators have recently requested funding from the National Science Foundation (NSF) with a bigger mission in mind: to establish a national hub for regenerative tissue engineering at NCSU. Currently, 114,000 Americans are waiting for organ transplants, and the donor options are limited, so engineered tissues and organs hold the greatest promise for them.

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[Images: North Carolina State University and the University of North Carolina at Chapel Hill]