Abstract: Objective To explore the effect of transplanting poly (lactic-co-glycolic acid) (PLGA) scaffolds seeded with neural stemcells (NSCs) and Schwann cells (SCs) on spinal cord injured rats and the mechanism. Methods NSCs and SCs were cultured in vitro andthen seeded into the directional PLGA scaffolds. Then PLGA-cell complexes were implanted into the spinal cord hemisected rats, whichwere divided into PLGA group, PLGA+NSCs group and PLGA+ NSC+SCs group. The rats were tested with cortical motor evoked potentials(CMEPs) and Basso-Beattle-Bresnahan (BBB) score. Then, the rats were further ipsilaterally or contralateral hemisected at T6 and testedwith CMEPs and BBB score again. Results The incidence of recovery and the amplitudes of CMEPs were the highest in PLGA+NSCs+SCs group. The rats exhibited a gradual improvement in hindlimb locomotor function in score. The BBB score was the least in the PLGAgroup in the 2nd week or later. After retransected ipsilaterally, the CMEPs disappeared again and the BBB score improved quickly. But afterretransected contralaterally, the rats were completely paraplegia. Conclusion The directional PLGA scaffolds seeded with NSCs and SCs facilitatethe recovery in spinal cord injured rats, which may associate with axonal regeneration and functional connections, but play a limitedrole.

Key words: spinal cord injury, tissue engineering, neural stem cells, Schwann cells, poly (lactic-co-glycolic acid), scaffold