Background  Schwann cells are important components of the nervous system, providing necessary signals and spatial cues to promote axonal regeneration and induce target nerve regeneration. Adipose mesenchymal stem cells are widely sourced and have clear effects in the direction of regenerative medicine, and exosomes play an important role in regulating regeneration as an important mediator of information between cells of the nervous system.

  Objective  To explore the effect of adipose-derived stem cells-derived exosomes (ADSCs-exos) on the function and early neural regeneration characteristics of Schwann cells.

  Methods  ADSCs-exos were extracted for identification; ADSCs were identified by microscopic observation and flow cytometry, and ADSCs-derived exosomes were extracted by ultracentrifugation and photographed by transmission electron microscopy; ADSCs-exos were co-cultured directly with rat Schwann cells to observe the effect of ADSCs-exos on the proliferation of Schwann cells. Eight female SD rats were taken, and matrigel matrix gel was injected into commercial silicone tubes with ADSC-exos to construct nerve grafts for the exosome group; matrigel was injected into commercial silicone tubes with PBS for the empty catheter group (Hollow), with 4 rats in each group. The 1 cm sciatic nerve defect model was constructed, and the nerve grafts were sutured between the proximal and distal nerve stumps and placed back in the cage after suturing the wound. At 3 weeks after removal of the nerve grafts, the axonal regeneration was evaluated.

  Results  ADSCs were successfully extracted and were able to express the MSC surface marker proteins CD73, CD90, and CD105. ADSCs-exos were successfully extracted and the phospholipid bilayer structure could be observed under transmission electron microscopy. In the co-culture system of ADSCs-exos and Schwann cells, the proliferation of Schwann cells at 24h and 48h was compared, and the proliferation of Schwann cells showed a significant dose-dependent relationship with the concentration of ADSC-exos. The results of animal experiments showed that axonal growth was significantly better in the exosome group than that in the Hollow group at three weeks (P < 0.05).

  Conclusion  ADSCs-exos can promote the proliferation of Schwann cells, and the axon growth length of ADSCs-exo-loaded neural grafts is superior at 3 weeks.