Combined transplantation of neural stem cell and protoplasmic astrocyte in the treatment of spinal cord injury following the semi-cut cavity in rats

Objective To observe the morphological and functional recovery of rat spinal cord after transplantation of neural stem cell (NSC) and protoplasmic astrocyte (PAS). Methods Sixty Wistar rats, which were injured on the left side of L1-L2 spinal cord, were randomly divided into injury group ( Group A), PAS transplantation group ( Group B), NSC transplantation group ( Group C), combined PAS and NSC transplantation group ( Group D, NSC:PAS =2:1 ), 15 rats in each group. The BBB scale, motor evoked potential (MEP) and somatosensory evoked potential (SEP) of lower limb were examined at 1,4 and 8 weeks after injury. The injured spinal cords were stained by hematoxylin-eosin, Nissl and Holmes to observe the morphological changes of transplants at eight weeks after injury. Results (1) There was significant difference in behavior among groups at four weeks after injury. At eight weeks after injury, the hindlimb in Group D could support body weight, and forelimb could collaborate with hindlimb during movement. There were certain improvements of the behavior of rats in Groups B and C. The active extent of the hindlimb was improved, but the hindlimb still could not support body weight. There was significant difference among four groups. (2) At one week after injury, sensory and motor functions in all groups were rehabilitated differently. At four and eight weeks after injury, the latencies of peak N1 and P1 became shorter in Groups B, C and D, especially Group D (P<0.01 ). (3) At eight weeks after injury, the injury in Group A was much severe, with few cambiums. The cavity was basically closed in Groups B, C and D, with no obvious inflammation. Lots of diversified regenerative astrocytes were observed in Group B, and the gelatinous fibers were disorderly arrayed. No neuron was observed in Group B. Lots of cambiums (mainly astrocytes) and a few neurons could be seen in Group C, with the regenerated fibers connected. The cavity was fully closed in Group D, with more regenerative neurons with dendrites than in Group C. Conclusions NSC and PAS can not only survive and differentiate when they are transplanted to the injured spinal cord, but also repair the injured area in terms of structure and function. Key words: Neural stem cells;  Protoplasmic astrocytes;  Spinal cord injuries;  Regeneration