Introduction: This study was performed to assess the effects of nerve gap repair with isogenic epineural tubes filled with isogenic bone marrow stromal cells (BMSC) as an alternative to autograft repair.
Methods: A total of 24 epineural tubes were transplanted as a conduit to bridge 20 mm nerve gap defects in 2 experimental groups. In group 1, the tube was filled with saline, whereas in group 2 with isogenic BMSC prestained with PKH-dye. In all, 12 autograft sciatic nerve repairs served as a control. Sensory and motor recovery was evaluated by gastrocnemius muscle index; pinprick, toe-spread tests; and somatosensory-evoked potentials at 6 and 12 weeks postrepair. Histomorphometry and immunostaining were also performed.
Results: Evidence of successful nerve regeneration was present in all animals at 6 and 12 weeks. There were no significant differences between experimental groups in functional recovery--toe-spread and pinprick tests; however, epineural conduit groups trended toward better toe-spread scores compared with autograft repair at 6 weeks. All animals had full sensory recovery as evaluated by pinprick at 12 weeks. Saline group had significantly higher gastrocnemius muscle index compared with other groups at 6 weeks; however, no differences were noted at 12 weeks. Histomorphometrical assessment did not reveal superiority of any group at 6 weeks postrepair. However, at 12 weeks, the BMSC group had significantly increased myelin thickness compared with other groups and larger diameter nerve fibers than autograft. In group 2, PKH-positive cells and expression of nerve growth factor, Laminin B2, glial fibrillary acidic protein, and vascular endothelial growth factor were confirmed. nerve growth factor- and glial fibrillary acidic protein-positive BMSC were also found inside the tube.
Conclusion: The epineural tube is a viable, naturally occurring biologic conduit for nerve repair. Cotransplantation of BMSC-enhanced nerve regeneration by means of increased myelinization and expression of neurotrophic factors. Overall, obtained results with epineural tube/BMSC construct were comparable to autograft repair.