That scar tissue was thought to be one of many factors researchers were up against in nerve regeneration if months passed after the injury. Researchers in the study used a "triple combination therapy": they combined the injured nerve cells, placed a "bridge" made of stem cells at the injured spot, and flooded the area around the spinal cord with chemicals naturally found in the body that help tissues grow.
By using combination therapy, as neurology expert Dr. Naomi Kleitman noted, "[One of the] really significant finding[s] here is that the nerve fibers grew out of the 'bridge' across the injury site, and into the spinal cord beyond.
"This is one of the best demonstrations of successful growth in chronic injuries we've seen," said Kleitman, program director of repair and plasticity at the National Institutes of Health in Bethesda, Md. "But it's also one of the first of its kind. It will take quite a bit more work to build on this proof-of-principle to figure out how to make such a strategy practical, safe and effective in clinical settings."
The new study could offer a new direction for research on human patients as well. All studies in the past have been targeting treatment right after spinal cord injury, which means that a quarter of a million spinal-cord patients who suffer from chronic injury were being left out. Nerve cells in this study were shown to re-grow a year after the injury.
The implications of the research, experts agreed, are significant.
"[I]ndividuals with long term, chronic injuries, could equally benefit from a treatment [as those with acute injury], when it comes available," says Dr. George Smith of the University of Kentucky.
And the findings also offer a glimmer of hope for researchers in the field.
"[I]t hammers home that given enough research money, resources, and manpower, it can be done, and that spinal cord regeneration research shouldn't be limited to those freshly injured, but that major improvement in those chronically injured is potentially in the (distant) future," Jenkins said.