Transplantation Of Astrocytes From Human Embryonic Stem Cells Promote Neural Axon Regeneration After Spinal Cord Injury

Objective:To explore the regenerative abilities of the axons of the descending corticospinal tract(CST)and serotoninergic axons,to evaluate the functional recovery after the astrocyte transplantation,the complete transection model of spinal cord injury was established,and two types of astrocytes,NPC-Astros and Olig2PC-Astros which are derived from human embryonic stem cells,were transplanted into the spinal cord lesion areas.Methods: Firstly,the morphological differences of cultured NPC-Astros and Olig2PC-Astro were identified by immunofluorescence.Secondly,the T8 segment of the mouse spinal cord were completely transected,and NPC-Astros and Olig2PC-Astros were transplanted into the lesion areas 1 day after injury.Thirdly,the experimental mice were sacrificed respectively at 2 and 8 weeks after cell transplantation to observe the cell survival and the migration of the transplanted NPC-Astros and Olig2PC-Astros by immunohistochemistry(IHC).Fourthly,the experimental mice were sacrificed at 10 weeks after cell transplantation to observe the axonal regeneration of CST and serotoninergic system by axon tracing and IHC.The CST which is critical for fine motor movement was anterogradely traced by p AOV-CAG-EGFP-2A 2 weeks before scarification,and the descending serotoninergic axons which modulate the activity of spinal motor system were labeled by IHC with 5-hydroxytryptamine(5-HT)antibody.Finally,Basso Mouse Scale(BMS)scores and spinal cord evoked potentials were used to evaluate the hind limb locomotor function and transmission of neural electrical signals between the spinal tissue rostral to the lesions and hind gastrocnemius.Results: The human embryonic stem cells-derived NPC-Astros and Olig2PC-Astros both expressed the astrocytes' markers GFAP(glial fibrillary acidic protein)and S100? cultured in vitro,and can be labeled by h M(human mitochondria)and h N(human nucleus)antibody.The two types of astrocytes differs in the morphology.2 and 8 weeks after cell transplantation,we observed the survived NPC-Astros and Olig2PC-Astros in the lesion areas and they migrated rostrally and caudally from lesion site.The regenerated axons of CST and serotoninergic system were observed in the lesions,growing through the lesions and projecting to the caudal spinal cord.The BMS scores was slightly raised and the evoked potentials between rostral spinal tissue to hind limb gastrocnemius was elevated after NPC-Astros and Olig2PC-Astros transplantation.Conclusions: NPC-Astros and Olig2PC-Astros which are derived from human embryonic stem cells can survive in the spinal cord lesion areas and migrate into the rostral and caudal spinal cord regions.Transplantation of NPC-Astros and Olig2PC-Astros promotes the axonal regeneration of CST and serotoninergic system after spinal cord injury.These positive effects result in slightly increased Basso Mouse Scale scores and elevation of electrophysiological transmission between the lesioned spinal cord and hind limbs compared with vehicle-treated control animals,which indicate the motor function of hind limbs was improved at some extend.Our results show that the two newly generated astrocytes can play an important role in the repair of spinal cord injury in mice,which is valuable for the further application of cell therapies in the treatment of spinal cord injury and other central nervous system diseases.