Implantation of Schwann cells in rat tendon autografts as a model for peripheral nerve repair: Long term effects on functional recovery

Cultured Schwann cells in tendon autografts for nerve repair improve the early phase of nerve regeneration in rat sciatic nerves as judged by the rate of axonal outgrowth. We tested the long-term effects on functional recovery using measurements of muscle force, the number of axons and myelination, using morphometry. In addition, we recorded wet weight of the gastrocnemius muscle. Schwann cell cultures were prepared from predegenerated nerves. Ten and 15mm defects in rat sciatic nerves were bridged using bilateral tendon autografts with Schwann cell-seeded tendon autografts on one side, and untreated tendon autografts on the other. Animals were evaluated at six and 12 weeks, respectively. At six weeks, myelination, as judged by G-ratio (ratio of axonal diameter to diameter of nerve fibres), was significantly increased in tendon autografts pretreated with Schwann cells in 10mm defects. No such difference was seen in the 15 mmdefects. We found no difference in functional recovery, other morphometric variables, or muscle weight between the two grafts. We conclude that early effects on nerve regeneration using transplantation of cultured Schwann cells in rat sciatic nerves are temporary. Other strategies are necessary to obtain lasting effects on functional recovery.