Silencing natural growth inhibitors may make it possible to regenerate nerves damaged by brain or spinal cord injury, finds a study from Children's Hospital Boston.
In a mouse study published in the November 7 issue of Science, researchers temporarily silenced genes that prevent mature neurons from regenerating, and caused them to recover and re-grow vigorously after damage.
Because injured neurons cannot regenerate, there is currently no treatment for spinal cord or brain injury, says Zhigang He, PhD, Associate Professor of Neurology at Children's and senior author on the paper. Previous studies that looked at removing inhibitory molecules from the neurons' environment, including some from He's own lab, have found only modest effects on nerve recovery. But now He's team, in collaboration with Mustafa Sahin, MD, PhD, Assistant Professor of Neurology at Children's, demonstrates that re-growth is primarily regulated from within the cells themselves.
"We knew that on completion of development, cells stop growing due to genetic mechanisms that prevent overgrowth," explains He. "We thought that this kind of mechanism might also prevent regeneration after injury."
The key pathway for controlling cell growth in neurons, known as the mTOR pathway, is active in cells during development, but is substantially down-regulated once neurons have matured. Moreover, upon injury, this pathway is almost completely silenced, presumably for the cell to conserve energy to survive. He and colleagues reasoned that preventing this down-regulation might allow regeneration to occur.