UC San Diego School of Medicine’s Translational Neuroscience Institute made its latest breakthrough in the treatment of spinal cord injuries after the culmination of 30 years of research. In a paper published on Aug. 22, a team of researchers led by Dr. Mark Tuszynski used rats as a model to find that STEM cells could significantly impact the rehabilitation and repair of injured spinal cords. 

“It’s very challenging to try and regenerate the injured spinal cord; the central nervous system doesn’t regenerate naturally very well,” Tuszynski said. “Axons are not typically capable of regrowing when they have been cut. But there have been some recent breakthroughs that have been encouraging, and one of them is the use of stem cells.”

Researchers chose stem cells as a treatment due to their regenerative and fast-growing properties, a notable contrast from the slow-growing adult nerve cells, according to Tuszynski. He noted that stem cells are able to redevelop a substantial amount of axons compared to regular nerve cell counterparts. 

“Before using stem cells, we achieved the growth of about 100 axons for a distance of one millimeter through the injured spinal cord. And now with stem cells, the stem cells will extend 10s of 1000s of axons, or distances of 50 millimeters,” Tuszynski said.

In the experiment conducted by Tuszynski and his colleagues, the spinal cords of rats were exposed and damaged to simulate the effects of a spinal cord injury in humans. Half of the injured rats then received an injection of stem cells in the area of the damaged spinal cord. 

After inducing the injury, the researchers waited one to two weeks so that the stem cells survive better once they are implanted. Tuszynski said this will be important to keep in mind once they need to operate on humans. 

 “And that’s also the most clinically relevant way to think about translating this technology to humans, because most humans wouldn’t undergo surgery to repair the spinal cord immediately… they would be stabilized medically first,” Tuszynski said.

Afterward, the rats underwent a rehabilitation technique involving them reaching, grabbing, and grasping for food in order to repair their motor function. Both the control group and treatment group underwent these rehabilitation tasks and had their motor abilities documented. Following the rehabilitation period, the stem cell treatment yielded significant improvements. 

“The control injured rats lost about 75% of their ability to retrieve the food rewards. And the rats that received rehabilitation, and a stem cell implant, regained about 50% of their function. It was a significant improvement compared to the untreated rats,” explained Tuszynski.

For Tuszynski, the trial results represent significant progress in addressing spinal cord injuries in humans, where rehabilitation and therapy are typically the only means of treatment. For individuals disabled and impaired by spinal cord injury, this could significantly improve their quality of life. 

“This means if you had a human with a cervical spinal cord injury, and you’re trying to improve hand function … they could reach out their hand, put it around a glass or fork and be able to bring it to their mouth and feed themselves,” Tuszynski said.  “It might mean that if they can’t control a hand control for a motorized wheelchair, now maybe they can reach out to that hand control and be able to control the wheelchair themselves. It would be extremely valuable to get even that degree of recovery, because right now, there’s nothing.”

Tuszynski anticipates human trials would begin in two years, with an eventual goal of stem cell treatment being medically available for all patients.

Art by Ava Bayley for the UCSD Guardian