Schwann-like mesenchymal stem cells within vein graft facilitate facial nerve regeneration and remyelination

To compare the ability of bone marrow mesenchymal stem cells (MSCs) and transdifferentiated Schwann-like MSCs (tMSCs) in promoting transected facial nerve branches repair in a rabbit model of injury, rabbit tMSCs were induced from bone marrow MSCs, and Schwann cells markers were assessed by Western blot analysis. The left facial nerve buccal branch was transected to form a 1-cm gap in 54 rabbits, and the gaps were immediately bridged using autologous vein grafts. Animals were then randomly assigned to three groups: vein graft (VG); VG + MSCs, and VG + tMSCs (n = 18/group). Saline, autologous MSCs, and Schwann-like tMSCs were injected into vein conduits. Rabbits were sacrificed at week 4, 8, and 16 post-surgery. Facial nerves regeneration and myelination were analyzed by functional, immunohistochemical, and morphological tests. In addition, myelin protein genes expression, including peripheral myelin protein 22 (PMP22), myelin protein zero (P0), and myelin basic protein (MBP), in transplanted cells in vivo were assayed using real time quantitative-reverse transcription–polymerase chain reaction (RT–PCR). Rabbit tMSCs expressed Schwann cells markers, and results demonstrated better facial nerve functional recovery in the VG + tMSCs group, with earlier horseradish peroxidase (HRP) positive neurons appearance and a greater number of MBP positive myelinated axons since 4 weeks after transplantation. Moreover, RT–PCR analysis showed transplanted tMSCs in vivo expressed higher myelin proteins at mRNA level than those of MSCs during the first 8 weeks of neural regeneration. This study suggests that rabbit transdifferentiated Schwann-like MSCs within autogenous vein graft accelerate transected axons regeneration and achieve better remyelinization.

Research highlights
► Rabbit bone marrow mesenchymal stem cells could be induced to Schwann-like cells.
► Schwann-like cells within vein graft accelerates transected axonal extension.
► Schwann-like cells within vein graft upgrades remyelination rate and quality.