BDNF Gene-Modified Schwann Cell Combined Tissue Engineering Technique Treatment Peripheral Nerve Injury AbstractObjective: BDNF gene-modified Schwann cells combined with tissue engineering to treat peripheral nerve injury. Methods: Morphology, immunohistochemistry, tissue engineering techniques, and functional assessment were used to determine the effects of transgenic peripheral nerve (PN) injury. Transplantation-modified Schwann cells (SCs) from ex vivo replanted grafts express brain-derived neurotrophic factor (BDNF), secretion of ciliary neurotrophic factor (CNTF) or neurotrophin 3 (NT3) form. The graft was used to repair a unilateral 25px defect of rat phrenic nerve and outcome after 10 weeks compared to normal nerves and various controls. Results: The number of regenerated βIII-Tubulin-positive axons in all grafts was similar except for CNTF (Immunostained axon minimal). The number of fibers in the cell-free, untransduced SCs and NT3 groups was significantly reduced while using the PanNF antibody, indicating a lack of large-caliber axons. In addition, NT3 grafts contain the most number of sensory fibers, identified by IB 4 or CGRP. Examination of semi-thin sections and ultrathin sections showed heterogeneous graft morphology, particularly in BDNF and NT3 grafts, where clustered tissue was evident. Unmyelinated axons loosely organized in many Remak bundles in NT3 grafts, while the BDNF graft group showed the lowest ratio on: the most refined axons, myelin axons. Gait analysis showed that the standing posture width of CNTF and NT3 transplanted rats increased, while the injured left hind limb length of NT3 transplanted rats increased significantly, indicating that the sensory sensitivity of these animals was enhanced. Conslusion: Selective expression of BDNF, CNTF or NT3 by transgenic SCs has different effects on PN graft morphology, number and type of regenerated axons, myelination and motor function. Keywords: BDNF gene; peripheral nerve injury; Schwann cell