Repair of axons
, a long, thin, electrical impulse transmitting type of nerve cell, was key to the research team's two-year-long investigation of 654 genes that regulate axon growth, ScienceDaily reported
, and their findings, which could help stroke and spinal cord injury patients, have been published in the September 22 issue of the journal Neuron
During this extensive gene survey, the team identified 70 axon growth promoting genes, as well as six more that inhibit regrowth of the cells.
Finding the six genes that repress axon regrowth could allow the development of treatments that eliminate inhibiting factors, while growth-promoting treatments could be developed from knowledge of the other 70 genes, some of which were already known to perform other regulatory functions, the team was surprised to learn.
To simplify (as much as possible) the process of finding this set of key genes, the team experimented on more than 10,000 tiny, transparent roundworms, scientifically named C. elegans
(a popular model for genetic studies), to develop mutants of all 654 genes the researchers suspected played a key role in axon regrowth regulation in mice, fruit flies and worms.
After using green florescent protein to label the roundworm neurons, the researchers damaged specific axons using a precision surgical laser and examined each after 24 hours for regrowth or lack of growth.
Though worms and mammals differ greatly, Chisholm and his team expect to discover the 76 genes they identified function similarly in more complex organisms because evolution preserves core molecules along with some of the roles they play; already new experiments are being done on mice in collaboration with other teams to verify these connections.
Lead author UC San Diego biologist Andrew Chisholm explained
this study was groundbreaking because, "We don't know much about how axons re-grow after they're damaged. When you have an injury to your spinal cord or you have a stroke you cause a lot of damage to your axons. And in your brain or spinal cord, regeneration is very inefficient. That's why spinal cord injuries are basically untreatable."
In related news, ScienceDaily reported: other approaches to researching nerve cell regeneration undertaken by separate teams in recent years have involved stem cells
processes and the activities of the nerve cells known as astrocytes