Regenerating Nerve Cells

It was once thought that nerve damage and spinal cord injuries were hopelessly irreversible, but research into how certain animals are capable of regeneration has led to new insights into tissue repair in humans.

One of the most remarkable examples is the zebrafish, which can fully reverse a severed spinal cord without intervention in as little as eight weeks. First, bridge cells (called glia) extend projections across a wide span of the injury to distances tens of times their own length. The nerve cells follow once these bridges have been formed. When scientists conducted a search for abrupt changes in gene activity immediately following injury, they found that one protein – called connective tissue growth factor (CTGF) – was found in high levels in the supporting glia cells, and when CTGF was genetically deleted, the fish indeed failed to regenerate.

This led them to investigate whether the human CTGF protein (which shares 90 percent of its genes with that of zebrafish) would have an effect on regeneration rate in the fish. The findings indicate that the human gene actually accelerated regeneration to the point where the fish were swimming better within two weeks.

The researchers are careful to point out that healing is a much more complex process in mammals partly due to scar tissue formation. However, they intend to continue experiments on mice to determine whether the protein can be controlled to improve its performance in humans.