Figure 1.

In vivo preclinical model of RA injury with delayed reimplantation of lumbar roots and experimental design. (A) Schematic of the procedure. Spinal cord with the nerve roots from control, root-avulsed (RA), and reimplanted (RE) animals. The L3-L6 spinal roots were detached and inserted into a silicone tube after RA injury. At 14 dpi, the tube was removed, and the injured spinal roots were re-inserted onto the spinal cord at the same lumbar level. Photographs showing the spinal cord (SC) and ventral roots (VR) inside the tube (left), root appearance after removing the tube (middle) and once roots were apposed underneath the spinal cord (right), during reimplantation surgery at 14 dpi. (B) Workflow of the experimental design. NH treatment was administered from the day of injury dissolved in the drinking water refreshed every three days for 6 months. Fourteen days post avulsion, a group of animals were reimplanted. A week later, some animals were sacrificed to evaluate MN survival (short-term period: 3 weeks post-RA injury or 1 week post-RE). The rest of animals were evaluated once per month with electrophysiological tests. One week before the end of the 6-month follow up period, we intramuscularly injected True Blue retrotracer at the tibialis anterior (TA) and the gastrocnemius (GA). (C) Electrophysiological CMAP recordings of control animals (CTL) and animals after RA and before RE (Injured).