Possible Regeneration of Damaged Nerves
August 12, 2012 § Leave a comment
A serious injury can have lasting effects on victims of violent incidents such as car accidents, stabbings, and gunshot wounds, specifically in their nervous systems. Nerves and blood vessels can be split, bones can be broken, and cells can be damaged in such a way that, while wounds may heal and scars fade, the body never forgets.
The ruined debris from these injuries is often spread throughout the body like a wreckage site, making it extremely tricky to rectify. Highland Hospital neurosurgeon Jason Huang, M.D., who worked with Iraqi soldiers injured on the battlefield, is well aware that nerve damage is among the most difficult to treat.
Huang, now back at his University of Rochester Medical Center laboratory, is working with a team to increase the success of methods by which doctors can repair nerve damage. In the journal PLoS One, Huang and his colleagues published a report that there may be a specific group of cells useful in nerve transplantation.
Huang determines that, “Our long-term goal is to grow living nerves in the laboratory, then transplant them into patients and cut down the amount of time it takes for those nerves to work.” He explains that for a damaged nerve to repair itself, the two disengaged parts of the nerve must somehow reunite through a complicated labyrinth of tissues and cellular structures, then reconnect. For a small wound such as a scrape or a paper-cut, this occurs fairly easily, but for more destructive injuries, the nerve cannot repair itself without some kind of intercession.
Typically, the transplantation of nerve tissues from elsewhere in the patient’s body serves to scaffold for the repairs, like a rough sketch, that new nerves can fill in to bridge the gaps. The fact that these tissues come from the patient’s own body ensure that the immune system does not attack it.
Unfortunately in the case of severely injured patients, there is no healthy nerve tissue available from their own bodies. They must seek alternatives. Other options include nerve transplantation from human cadavers or animals, but this substitute involves lifelong dependency on extremely potent immunosuppressant drugs that come with a host of side effects.
The technology established by Huang and his team is called NeuraGen Nerve Guide. It includes a hollow, absorbable collagen tube that nerve fibers can grow and travel through to find each other. It is used to mend nerve damage over distances of less than half an inch long.
The team performed experiments on rats and found that dorsal root ganglion neurons (DRG cells) help to produce solid, healthy nerves, without inciting an undesirable reaction from the immune system. The team compared several methods to bridge half an inch nerve damage gaps in rats. They performed transplantations between rats combined with NeuraGen technology, comparing results of pairing NeuraGen with DRG cells, Schwann cells, and on its own. After four months, the tubes equipped with the DRG or Schwann cells were found to produce healthier nerves. Compared with each other, DRG cells incited the least amount of attention from the immune system, while Schwann cells attracted twice as many macrophages and more immune interferon gamma.
Schwann cells are currently more often preferred as potential partners in nerve transplantation, even though they cause problems due to the immune system’s reaction to them. Huang says, “The conventional wisdom has been that Schwann cells play a critical role in the regenerative process. While we know this is true, we have shown that DRG cells can play an important role also. We think DRG cells could be a rich resource for nerve regeneration.” This is great news for the yearly 350,000 patients in the United States who experience severe injuries to their peripheral nerves.
Huang’s laboratory is just one of many medical technology institutions geared towards the improvement of treatment methods for nerve damage. The team is currently collaborating with Douglas H. Smith’s team at the University of Pennsylvania to create DRG cells in the laboratory by stretching them. Stretching them encourages growth at the rate of one whole inch every three weeks. Instead of leaving it up to the nerves to travel and find each other inside the body, the team endeavors to grow the nerves externally in preparation for transplantation. This speeds the process of nerve repair.
“A Step Forward In Effort to Regenerate Damaged Nerves”. (February 21, 2012). Neuroscience News. March 2, 2012. http://neurosciencenews.com/regenerate-damaged-nerves-dorsal-root-ganglion/.