With the use of custom-built 3D printers, a team of researchers has developed a novel technique that combines two already utilized methods–injected stem cells and implanted scaffolds— to treat spinal cord injuries.

Researchers from the University of Minnesota were successfully able to print scaffolds, as well as stem cells—which will differentiate into neurons and help connect living nerve cells above and below the injured site on the spinal cord—using a single custom-built 3D bioprinting system.

“Basically the idea is that you go to the site of the injury in the spinal cord and you implant this scaffold,” said Michael McAlpine, PhD, the University of Minnesota Benjamin Mayhugh Associate Professor of Mechanical Engineering in the University’s College of Science and Engineering, in an interview with R&D Magazine. “The idea is that the scaffold will match up to the injured site and the cells would basically be a bridge between the healthy regions of the spinal cord and restore function, restore communication across the injured site.”

How it works

Creating the right type of 3D bioprinter was the first step, explained McAlpine.

 “The base technology that fuels this whole project is we develop our own 3D printers that can print a variety of different materials,” McAlpine said. “Conventional 3D printers basically only print hard plastic but our printer can print different materials, including electronic materials, soft materials, hydrogels, silicones, and a huge range of materials.”

The 3D printed scaffold is made of silicon and serves as a platform for specialized cells that are then 3D printed on top of it.  

To create the stem cells, the researchers begin with any type of cell from an adult, such as a skin cell or blood cell. They then reprogram the cells into neuronal stem cells using new bioengineering techniques.

The scientists then print the cells onto a silicone guide with the same 3D printer that is used to print the guide.

According to McAlpine, they were able to keep 75 percent of the cells alive during the 3D printing process. One of the advantages of the new technology is that the researchers can organize the cells on the device in a specific manner, he said. 

The researchers believe that the technology could eventually be used for patients to alleviate pain, as well as regain some functions lost from the injury, including control of muscles, bowel and bladder.

According to McAlpine, the researchers have begun to implant the new device into rats.

“The paper itself showed that we can print the scaffold and then print the cells into the scaffold and differentiate these stem cells into healthy, active neurons, which had not been shown before,” he said. “Now to take that and start to implant these things in rats and see if they can recover from a spinal cord injury, that would be another big breakthrough.”   

There are currently about 285,000 people in the United States who suffer from spinal cord injuries, with about 17,000 new spinal cord injuries nationwide each year.

A video related to the research can be found here: https://z.umn.edu/3Dguidespinalcord.

The study was published in Advanced Functional Materials.