Electro-Acupuncture Promotes the Survival and Differentiation of Transplanted Bone Marrow Mesenchymal Stem Cells Pre-Induced with Neurotrophin-3 and Retinoic Acid in Gelatin Sponge Scaffold after Rat Spinal Cord Transection

In the past decades, mesenchymal stem cells (MSCs) as a promising cell candidate have received the most attention in the treatment of spinal cord injury (SCI). However, due to the low survival rate and low neural differentiation rate, the grafted MSCs do not perform well as one would have expected. In the present study, we tested a combinational therapy to improve on this situation. MSCs were loaded into three-dimensional gelatin sponge (GS) scaffold. After 7 days of induction with neurotrophin-3 (NT-3) and retinoic acid (RA) in vitro, we observed a significant increase in TrkC mRNA transcription by Real-time PCR and this was confirmed by in situ hybridization. The expression of TrkC was also confirmed by Western blot and immunohistochemistry. Differentiation potential of MSCs in vitro into neuron-like cells or oligodendrocyte-like cells was further demonstrated by using immunofluorescence staining. The pre-induced MSCs seeding in GS scaffolds were then grafted into the transected rat spinal cord. One day after grafting, Governor Vessel electro-acupuncture (GV-EA) treatment was applied to rats in the NR-MSCs + EA group. At 30 days after GV-EA treatment, it found that the grafted MSCs have better survival rate and neuron-like cell differentiation compared with those without GV-EA treatment. The sustained TrkC expression in the grafted MSCs as well as increased NT-3 content in the injury/graft site by GV-EA suggests that NT-3/TrkC signaling pathway may be involved in the promoting effect. This study demonstrates that GV-EA and pre-induction with NT-3 and RA together may promote the survival and differentiation of grafted MSCs in GS scaffold in rat SCI.