US scientists have reported a major breakthrough on the road to treating spinal injuries that result in paralysis.

Paralysed rats were able to re-gain some bladder control after undergoing surgery to transplant nerve cells into the spinal cord.

Surgery was then combined with series of chemical injections. After three, and again at six months, the scientists discovered that rats who had received this combination of treatment showed bladder function again.

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Achieving cell growth after they have been transplanted has always proved difficult for scientists because of the scar tissue damaged cells produce as they respond to injury.

Instead Yu-Shang Lee, PhD, of the Cleveland Clinic, together with Jerry Silver, PhD, of Case Western Reserve Medical School, and others used a chemical that promotes cell growth and reduces scarring, creating an environment that cells are more likely to connect in.

This special “glue” boosts cell growth and breaks down scar tissue, encouraging the cells to regenerate.

The researchers found for the first time that injured nerve cells could re-grow for “remarkably long distances” of approximately 2cm, raising hopes for treating paralysed patients in the future.

Yu-Shang Lee, PhD, of the Cleveland Clinic, together with Jerry Silver, PhD, of Case Western Reserve Medical School, and others noted that whilst the animals did not regain the ability to walk, they did regain “a remarkable measure of urinary control".

“This is the first time that significant bladder function has been restored via nerve regeneration after a devastating cord injury,” Lee added.

“What was especially surprising and exciting was that a subset of nerve cells situated largely in the brainstem could slowly re-grow far down the spinal cord once a permissive environment that allowed them past the site of the scar was provided.

“What endows these particular neurons with such an innately high re-growth capacity is unknown but will be an extremely important area of research in the future.”

The study was published in the 26 June edition of the Journal of Neuroscience.