Why don't injured axons regrow ("regenerate") automatically?
During development, axons grow to their targets and appropriate connections are stabilised. However after childhood, axons lose their ability to grow. First, adult neurons stop making many important molecules that enable their growth. Second, the environment surrounding the mature neuron is very inhospitable for growth: there are molecules that actively prevent long distance axon growth.
How might we encourage injured axons to regrow?
We need to address both points. First, we need to find out which molecules within neurons cause axons to grow better. Second, we need to understand the factors surrounding neurons that constrain their regenerative ability.
Various laboratories around the world, including my own, address each of these questions using a range of different experimental approaches. We hope to develop therapies for improving function lost after stroke and SCI.