McMaster University

McMaster University

Faculty of
Health Sciences

McMaster researchers rewire spinal cord nerves to produce functionary recovery

August 5, 2003

McMaster University researchers have found that implantation of cells from the intestine into the spinal cord can promote the growth of nerve fibres which restore function.

The discovery is another step in the long road to developing ways to improve function after spinal injury, says neuroscientist Dr. Michel Rathbone, a professor of medicine at McMaster.

"This is an exciting development, we know we're on the right path," said Dr. Rathbone.

An article on the recent development is being published in the medical journal NeuroReport this week. It was written by post doctoral fellow Dr. Shucui Jiang, Dr. Rathbone and professor of medicine Dr. Eva Werstiuk. The research is supported by the Canadian Spinal Research Organization (CSRO).

After spinal injury recovery of spinal cord function is limited; the environment of the spinal cord inhibits nerve processes from regrowing. The McMaster group found that cells called enteric glia, which support nerves in the intestine, when transplanted into the region of injured nerve fibres, stimulate the growth of the nerve fibres through the spinal cord. But, even more importantly, the regenerating fibres form correct connections, and restore function.

The McMaster group's initial studies were done on sensory nerves that enter the spinal cord and make connections with the motor nerve fibres. Lightly pinching the skin of the flank sends impulses into the spinal cord that relay to the motor nerve cells, causing them to fire. In turn, this elicits a reflex twitch of the muscle beneath the skin that was pinched - much like being tickled. The reflex is called the CTM reflex. If a sensory nerve is cut, it cannot conduct impulses so the reflex is lost. Even if the nerve re-joined, it does not regenerate into the spinal cord.

However, when enteric glia were implanted into the spinal cord at the point where the nerve entered, the regenerating nerve fibres penetrated into the spinal cord. After a month the reflex recovered, showing that the regenerating sensory nerves made correct and functional connections with motor nerve cells in the spinal cord. The success rate was about 80 per cent. Implantation of cells other than enteric glia neither stimulated nerve regrowth in the spinal cord nor functional recovery.

Dr. Jiang, a Brian Keown Fellow of the CSRO, said one day enteric glia may be used to treat individuals with spinal cord injuries, such as injuries in which nerves are torn from the spinal cord, as in some motor vehicle accidents and industrial injuries.

"Before we can proceed to clinical trials in humans, many further tests must be done with enteric glia. We must answer such questions as how many enteric glia to inject, and to find where in the injured spinal cord to inject them to achieve best results."

Dr. Rathbone also cautioned that it will take several years to move from research in rats to clinical studies in humans. "A number of problems must be solved. For example, the insulating layer - myelin - around the regenerating nerves must be restored," he said.

The CSRO, which has funded Dr. Rathbone's enteric glia research for ten years, is a national charity dedicated to the improvement of the physical quality of life for persons with a spinal cord injury through scientific and medical research.

Barry Munro, president of the CSRO, said "It is very rewarding, as a consumer and as a representative of many spinal cord injured people, to see a decade's worth of work show very positive results."

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