Tiny 3D Printed Device Could Save Injured Spinal Cords

The Minnesota team published their findings online in a recent edition of the Advanced Functional Materials journal. 

"This is the first time anyone has been able to directly 3D print neuronal stem cells derived from adult human cells on a 3D-printed guide and have the cells differentiate into active nerve cells in the lab," said Michael McAlpine, Ph.D. McAlpine served as a co-author of the study and works as the University of Minnesota's Benjamin Mayhugh Associate Professor of Mechanical Engineering in the University's College of Science and Engineering.

The team's innovation came out of necessity, the researchers explained in a statement. Currently, options for patients with spinal cord injuries are limited and normally involve reducing pain rather than trying to heal the injury itself. 

"This is a very exciting first step in developing a treatment to help people with spinal cord injuries," said Ann Parr, M.D., Ph.D., a co-author of the study and University of Minnesota Medical School Assistant Professor in the Department of Neurosurgery and Stem Cell Institute. "Currently, there aren't any good, precise treatments for those with long-term spinal cord injuries."

The process to create this 3D printed block took over two years. Unlike other cell treatments, the researchers start this new process with any kind of cell from the patient. They then reprogram the cell into a neuronal stem cell. Those stem cells get printed onto a silicone guide using a new 3D printing technique that allows the same printer to print both the cells and the guide. The guide makes sure the cells stay alive and then facilitates their change into neurons. 

"Everything came together at the right time," Parr said. "We were able to use the latest cell bioengineering techniques developed in just the last few years and combine that with cutting-edge 3D-printing techniques."

Overcoming Development Challenges

The researchers' prototype guide could be surgically implanted within the spinal cord injury and bridge the living cells on either side of the injury using the stem cells. Despite using the newest technology available, the prototype didn't come easily to the researchers. While not all the cells survived, enough lived during the prototype to make it a viable option for medical use. 

"3D printing such delicate cells was very difficult," McAlpine said. "The hard part is keeping the cells happy and alive. We tested several different recipes in the printing process. The fact that we were able to keep about 75 percent of the cells alive during the 3D-printing process and then have them turn into healthy neurons is pretty amazing."

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Next steps for the Minnesota team and their prototypes include further testing and then clinical trials. 

"We've found that relaying any signals across the injury could improve functions for the patients," Parr said. "There's a perception that people with spinal cord injuries will only be happy if they can walk again. In reality, most want simple things like bladder control or to be able to stop uncontrollable movements of their legs. These simple improvements in function could greatly improve their lives."