A man who was fully paralyzed is now able to stand after receiving an injection of reprogrammed stem cells into his injured spinal cord. The result, announced by researchers in Japan, marks a rare and powerful moment in a field where progress has been cautious and uncertain.
The clinical trial, led by neuroscientist Hideyuki Okano at Keio University in Tokyo, involved four adult men who had suffered complete spinal cord injuries. All were classified as having no motor or sensory function below the injury site.
Each received a dose of neural precursor cells derived from reprogrammed stem cells—cells that began as adult tissue but were reverted into a stem-like state capable of transforming into neurons and glial cells. We’ve also seen researchers use stem cells to treat vision-related issues.
The team monitored the participants for a year, measuring progress using the American Spinal Injury Association’s impairment scale. One individual improved to level D, meaning he could move freely enough to stand on his own. Another reached level C, with partial movement but still dependent on support.
The two other men did not show significant recovery, but none experienced serious side effects—a crucial finding itself. This is the first time a trial has used reprogrammed stem cells in this way for people with severe spinal injuries.
The approach builds on years of work showing these cells can become a wide range of tissue types. In this particular case, two million neural precursor cells were injected directly into each patient’s injury site, where they were expected to assist in repairing the damaged spinal cord—either by replacing lost cells, building support structures, or releasing beneficial proteins.
The researchers have not yet published their full results in a peer-reviewed journal, according to a report published by Nature. And while it’s still unclear how many of the transplanted cells survived or integrated into the spinal cord, the changes seen in two of the four patients have drawn cautious optimism from experts.
