Effect on the expression of nestin and synapsin I after spinal cord injury in rats

Abstract

Objective To investigate the effects and significance of site transplantation of allogenic bone marrow mononuclear cells （BMMNCs） on the expression of nestin and synapsin I in the local mieroenvironment of transected injury zone in spinal cord. Methods From a pool of 120 clean grade Wistar rats （ Irrespective of gender） , 87 rats were randomly （ random number） selected and subdivided into three groups. Sham operation group （n = 29 ） had lamineetomy done without inducing spinal cord injury. The model control group （n = 29 ） had laminectomy done followed by induction of complete spinal cord transeeted injury. Cell transplantation group （n = 29） had BMMNCs transplantation initiated after induction of complete spinal cord transected injury. Nestin and Synapsin expressions in all rats of each group were assessed on day 5, week 1, week 2 and week 4, respectively by using immunohistochemical and RT-PCRtechniques. Spread of Nestin positive and Synapsin I positive products along the spinal cord were assessed by use of MIAS-2000 image processing system analysis. Optical density of these products was then measured. Statistical data analysis was done using SPSS17. 0. Uniform variance analysis was done for inter group comparison using completely random design data, while paired sample comparison done with the Q test. For non-uniform variance, multiple samples were compared using design rank sum test with Kruskal-Wallis method, whereas paired samples rank sum test with Nemenyi method. P value of P 〈 0. 05 was regarded statistically significant, and P 〈 0.01 regarded highly statistically significant. Results Immunohistochemistry, RT-PCR and image processing system analysis showed model control group had increased nestin expression within the damaged zone 5 days after injury, reaching peak level at 2 weeks then significantly down regulated 4 weeks later. In cell transplantation group, nestin expression around spinal cord injury zone increased 5 days after injury and reached the peak level at 1 week, then subsequently significantly down regulated 4 weeks later. At each interval, there were significantly statistical differences between sham surgery group and model control group and cell transplantation group （P 〈 0.05 ）. Synapsin I expression appeared within the damaged area 5 days after injury, but at each interval, the expression of synapsin I in the model control group and cell transplantation group was lower than that in sham operation group. However, synapsin I in cell transplantation group was higher than that in model control group （ P 〈 0. 01）. Conclusions Allogenic bone marrow mononuclear cells transplantation may alter the local microenvironment and up-regulate the expression of nestin and synapsin I in the spinal cord injury model. Key words: Bone marrow mononuclear cells ; Spinal cord injury ; Cell transplantation; Nestin; Synaptophysin I; Spinal cord injury; Immunohistochemistry; RT-PCR