Intraneural OX7-saporin for neuroma-in-continuity in a rat model.

We employed 54 rats to devise a model of neuroma-in-continuity and explore the effect of the immunotoxin OX7-saporin on the neuroma. The left common peroneal, tibial or sciatic nerves were crushed by one 10-s application of a micro-artery forceps. At 3 and 6 weeks, the nerve was cut distal to the site of nerve crush, and retrograde fluorescent labeling was done. Pressure microinjection of 2 μl of natural saline or 2 μl of the immunotoxin conjugate OX7-saporin was done at the nerve stump 2 days later. Sacrifice was done after 3 weeks. In all control and saline-injection nerve specimens, gross observation and histology showed a neuroma-in-continuity. In 19 of the 24 OX7-saporin nerve specimens, gross observation showed a narrowed area at the site of nerve crush. Histology showed inhibition of neuroma-in-continuity formation. Fluorescent microscopy showed ablation of the labeled neurons in the dorsal root ganglia corresponding to the OX7-saporin subgroups.