Ten or fifteen years ago, if any one of the 6 million people estimated to be living with paralysis searched for treatment, they would likely have found hope in short supply. More often than not, they were told their condition was permanent.
Research since then has shown that if the damage from spinal cord injuries is dealt with immediately, there may be hope that some patients can avoid total paralysis. But if treatment is delayed, the chances of success quickly dwindle.
Now, in an unprecedented new study from the University of California, San Diego, published Wednesday in the journal Neuron, researchers say they were able to regenerate nerve cells up to 15 months after a spinal cord injury.
"All studies in the past have been right after the injury, but with a quarter million [people with chronic spinal injury], we needed a study that looked at re-growth one year after," said Dr. Mark H. Tuszynski, director of the Center for Neural Repair at UCSD and one of the authors of the study. "We found one can achieve this at impressive delays."
But like much of the other current paralysis research, this finding is only preliminary. The study was conducted only in rats -- so it is hard to say how it may apply to people. And while the data is promising, doctors specializing in spinal cord injury caution that this is at least a decade away from being rolled out as therapy for humans.
Moreover, the trial at hand was largely a test run; the nerves that the researchers regenerated in the rats were picked because they would be the most easy to study and simplest to re-grow. Additionally, while the nerves that were studied re-grew, they did not connect to the brain in the way needed to restore sensory or motor function.
"None of the animals had any improvement in neurological function," said Dr. Arthur Jenkins, co-director of Mt. Sinai Hospital's Neurosurgical Spine Program.
Other neurology experts agreed.
"This is still an animal model of an injury far from clinical trials," said Dr. Peter Konrad, director of functional neurosurgery at Vanderbilt University. We cannot tell whether this re-growth will actually make a patient walk again or regain feeling."
Still, those in the field said this is one step in what may one day be a hopeful future for chronic spinal cord injury patients. Dr. Edward Hall, director of the Spinal Cord and Brain Injury Research Center at the University of Kentucky in Lexington, calls it a "landmark study that is one of the first to investigate a combination therapeutic approach aimed at improving regeneration of spinal cord fibers across a spinal cord lesion."
"It's unbelievable," said Dr. James Harrop, associate professor of neurological surgery at Thomas Jefferson University Hospital. "You usually have all this scar, and the neurons can't get through the scar... Your body is sending signals so that it won't get better."
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.