A new gel, containing neural stem cells and growth chemicals, can regenerate nerve cells in a severed spinal cord, new research says.

Neural stem cells are cells that have the capacity to differentiate into nerve cells. Previous research has shown that adult mammals have neural stem cells and these can be used to repair broken or missing cells.

The gel was tested on rats with damaged spinal cords. Not only did the cells grow, but also integrated with the existing cells to form a network. The circuitry was checked "by stimulating the spinal cord four segments above the injury and recording this electrical stimulation three segments below," said Mark Tuszynski, MD, from University of California, San Diego and lead author of the study.

Researchers detected new relays at the broken sites. To confirm their findings, researchers again broke the spinal cord in the treated rats, just above the implant. They found that the circuitry broke again and the rats lost functional ability showing that the gel does repair a broken spinal cord.

The gel was tested on human cell lines. Researchers report that they obtained the same results.

"Using this method, after six weeks, the number of axons emerging from the injury site exceeded by 200-fold what had ever been seen before," said Tuszynski.

In the study, the rats that were given the gel treatment recovered lost body function whereas rats that weren't given the treatment did not. Researchers attribute this improvement to axon growth.

"The axons also grew 10 times the length of axons in any previous study and, importantly, the regeneration of these axons resulted in significant functional improvement," said Tuszynski,

The neuron growth was tracked by tagging the cells with a kind of biological dye, green fluorescent proteins (GFP). Using this method, researchers saw the cells grow, become neurons and develop into axons.