Doctors trying to fix damaged nerves

An oligodendrocyte nerve cell (red/purple) wraps around a polymer nanofiber (white/clear). Courtesy: University of Michigan

Nerve disease and injuries are tough to treat, largely because there's no way to regenerate many damaged nerve cells.

Neurologist Joseph Corey is trying to change that.

Corey and a team of scientists from the University of Michigan Medical School, the Veterans Administration Ann Arbor Healthcare System and the University of California, San Francisco used incredibly tiny polymer fibers -- only nanometers wide -- as a scaffold. They coaxed a certain type of brain cell, called an oligodendrocyte, to form a protective coating, called a myelin sheath, around the fiber. The artificial fiber mimicked the shape and size of the type of nerve cell that transmits signals, called an axon.

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Myelin sheaths protect axons, insulating them from ions in much the same way as electrical insulation protects wires from short-circuits. They also help the electrical current stay in the cells and let them communicate with each other faster. Myelin provides the pathways along which some nerve cells regenerate after an injury.

When a person has MS or cerebral palsy, the oligodendrocytes are damaged and don't function properly. That in turn affects the myelin sheaths, which start to break down.

The scientists haven't managed to make full-on nerves, but they do hope this work will tell them how to learn more, and maybe one day help people with MS or nervous system injuries. The use of the tiny fibers might reveal just what makes oligodendrocytes form myelin sheaths to begin with.

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If that process were better understood, they could understand how to get the cells to make new myelin sheaths and what makes nerves regenerate when they do. For example, nerves regenerate when we have minor injuries, but not when there is major damage to the spinal cord.

The authors reported the findings in Nature Methods.