Scientists in Cleveland have been able to achieve minor spinal cord function restoration in rats, and in doing, the hope is that the process could be a small step toward spinal cord repair in humans. That day could still be far off, but the research as described in a new report is at least headed in the right direction.
The researchers, who hail from the Cleveland Clinic and Case Western Reserve University, set out with a simple goal in mind: to restore bladder control in rats that had their spinal cords completely severed. If this same kind of research could yield success at the human level, it would reduce catheter usage, accidents, and even potential infections.
The process is rather complex, with each surgery taking up to five hours. At one time, the neuroscientist conducting such operations was doing so at a rate of up to three per day. The rat was first anesthetized prior to the procedure. A transection, which involves a complete separation of the spinal cord, was then conducted in the area of the rat’s chest. Such a complete cut was chosen so that researchers could be guaranteed that improvements to urinary function were the result of the process to come.
That process involved taking between 18 and 21 peripheral nerve tracts from the rat’s chest wall and grafting them onto the gap created during the transection. Although the nerves die when they’re cut, the tubes that they are encased by act as a sort of shield allowing for spinal nerves to grow, bridging the gap un-accosted. Using fibrin glue and growth-encouraging FGF and an enzyme called chondroitinase, the surgeon coated the fibers as a means to foster connection. To ensure that these grafts wouldn’t fail, wire was used to keep the animals’ vertebrae attached upon waking.
At that point, researchers had to exercise patience as they waited to see if their work would bear fruit. At the end of the observation period, the rats who had been put through the procedure had obtained not-quite normal urination patterns, but fairly close to such. Their bladders shrank and urine came more often and in smaller doses.
Among the hundreds of nerve fibers that had regrown in the interim, none were involved in complex activities. Those that had grown were responsible for activities that could be considered reflexive, such as the need to urinate.
The next step will involve testing out the method on older injuries and on larger animals, so it’s still a long way out from when the treatment could be available for people. The distance in human spinal cords is much greater, requiring quicker growth if the procedure were to work. However, working in favor of the research is the fact that urination is rats is actually more complex than it is in humans, and thus if it works at that level, the leap could eventually be made to our species.