Different effect on axonal outgrowth of application of non-absorbable or absorbable tubes around a nerve repair

We studied regeneration distance of rat sciatic nerve, with the sensory pinch reflex test and immunocytochemical staining for neurofilaments, four to 21 days after transsection, repair, and enclosure of the repair site in either a non-absorbable silicone tube or an absorbable polyglycolic acid (PGA) tube. The size of both tube-types was carefully selected so that they did not compress the repaired nerve. The opposite nerve was repaired and not inserted in a tube (control). The regeneration distances in repaired nerves enclosed in silicone tube were significantly longer than the control side at all time points, a result not seen when PGA tube was used. The number of proliferating non-neuronal cells (incorporation of 5-bromodeoxyuridine (BrdU)) was studied just proximal to the site of nerve repair after six days. Numerous stained cells were seen, but there where no significant differences between the groups. We conclude that outgrowth of sensory axons after transsection and repair of rat sciatic nerve with sutures can be increased by enclosing the site of repair in a silicone tube but not in a PGA tube. The effect is probably not related to the number of proliferative non-neuronal cells.