fig1

Figure 1. Increasing the rate of axonal regeneration (FK506) and the number of first-arriving pioneering axons (electrostimulation) improves function through different mechanisms. (A) A regenerating nerve illustrated by a bicycle race with each axon represented by a single cyclist and the finish line representing a suture line of previous repair. While there are some front-runners, representing pioneer axons, each cyclist travels at approximately the same speed (20 mph); (B) The addition of FK506 to the nerve regenerative environment has been shown to increase the speed of axonal regeneration. This would be as if the speed of the group of cyclists increased globally (to 30 mph), but the position between front-runners (pioneer axons) and followers is maintained; (C) The use of electrostimulation in a regenerating nerve has been proposed to promote a large number of axons to grow across a repair site more quickly rather than pioneer axons crossing the repair site with trailing axons to follow. Here, this phenomenon is represented by the pack of cyclists crossing the finish line (suture site) in a more coordinated manner, while the overall speed is maintained relative to no intervention.