Effects of transplanting bone marrow stromal cells on axonal and glial scarring after spinal cord injury

Objective To investigate the effects of bone marrow stromal cell (BMSC) transplantation on axonal and glial scarring after spinal cord injury (SCI).Methods Thirty New Zealand white rabbits were randomly assigned to a sham operation group (group A),a saline treatment group (group B) or a BMSC treatment group (group C).Group A served as controls,in which the canal was opened without damage to the spinal cord.In groups C and B SCI models were established with aneurysm clips and the rabbits of groups C and B were then given injections of BMSCs and saline solution respectively via the intra-intercostal artery at 1 week post injury.At 1 day,1 week,2 weeks and 4 weeks post injury,Basso Beattie-Bresnahan (BBB) scores were assessed to evaluate the recovery of locomotor function in the hind limbs.Spinal cord samples were harvested for HE and Nissl staining,and immunohistochemistry and image analysis were used to detect any changes in neurofilament (NF200) and glial fibrillary acidic protein (GFAP) in the injured spinal cords.Results The average BBB scores of group A were significantly higher those that of groups B and C at each time point,and those of group C were significantly better than those of group B at the 2nd and 4th week post injury.At the 4th week post injury,HE staining showed there was no glial scarring or cavities in group A,but that there was glial cellular proliferation,glial scarring and cavity formation at the injury site in groups B and C.In group C all were obviously less than in group B.Nissl staining indicated there were more typical neurons in group A,while there were a larger number of ruptured neurons,more degradation,and irregular remaining neurons in groups B and C.These abnormalities were again significantly more prevalent in group C.Immunohistochemical examination showed significant increases in NF200 positive neurons and GFAP in groups B and C compared with group A.The number of NF200 positive neurons was significantly higher in group C than in group B,but the GFAP positive area was significantly smaller in group C than in group B.Conclusion BMSC transplantation via the intercostal arteries can effectively improve axonal regeneration,attenuate glial cellular proliferation and reduce glial scar formation,promoting functional recovery after SCI,at least in rabbits. Key words: Spinal cord injury;  Intercostal arteries;  Bone marrow stromal cells;  Neurofilaments;  Glial fibrillary acidic protein;  Rabbits