Recently, however, a team at Children's Hospital Boston lead by Zhigang He, has been developing an alternate approach to the problem. Instead of trying to force existing nerve fibers to regrow, or by introducing new cells to take their place, the group manipulates the communication in the cells to "turn off" an apparent gene that tells the neuron to stop growing. With the gene shut down, then neuron is free to generate and flourish as it sees fit.
They have found at least three proteins involved with the critical myelin coating of neuronal axons, which actively work together to inhibit myelin growth. Blocking the proteins either genetically or chemically is being shown to promote the sprouting and re-generation of local structures in neuron networks.
The process is being tested in mice with spinal cord injuries by removing a special enzyme, called PTEN, that is activated in mature systems to limit cell growth. With the enzyme out of the picture, the cells think they are young again, and start to grow. No controversial stems cells, and no introduction of unnatural chemicals... just removing a little key that is in the way. Of course, it would likely be important to be able to replace the key once the damaged cells have rejuvenated, otherwise a cancer-like state might be a drastic side effect.
"Mice regain movement after spinal cord injury" :: Scientific American Observations :: August 8, 2010 :: [ READ ]
"PTEN deletion enhances the regenerative ability of adult corticospinal neurons", Kai Lui, et al., Nature Neuroscience, August 8, 2010 [ READ full article :: Download PDF ]
Image courtesy Wikimedia Commons.