Effect Of Cerebrospinal Fluid On The Proliferation And Differentiation Of Endogenous Neural Stem Cells

Spinal cord injury (SCI) is a tough problem in clinical treatment of. Achievement of isolating and culturing neural stem cell provided a new idea of treating SCI and make recovery of SCI possible. Although the ability of culturing neural stem cell has been successfully obtained, how to make in vitro cultured neural stem cell implanted into injury tissue survive and grow, and achieve regeneration of neural cell and functional reconstruction in injuried spinal cord, remain many technically problem unsolved. Neural stem cells exist in the subventricular zone (SVZ) of lateral ventricle in central neural system (CNS) throughout the life of adult mammals and proliferate responsively after SCI. SCI being occurred, it is the ideal method that endogeneous neural stem cell is regulated and differentiate into neuron and oligodendrocyte speedily, reconstituting injuried spinal cord and myelin sheath, and promoting function repair of spinal cords. Cerebrospinal fluid provided neutrition and protection for brain and spinal cord, which have similar chemical composition with extracelluar fluid of brain and spinal cord. Research showed that neural stem cell can survive, proliferate and differentiate in cerebrospinal fluid. Injecting nerve growth factor in lateral ventricle can make neural stem cell survive, proliferate and differentiate in cerebrospinal fluid. Cerebrospinal fluid can influence the formation of neuron and proliferation of neural stem cell.In the first Part, the author investigated the proliferation and differentiation of endogenous neural stem cell after rat Spinal Cord Injury.42Wistar rats were choosed to be divided into control group (A group) and spinal cord injuried group (B group). Animal model of spinal cord injury was established by clips impressing aneurysm, and then sections of injuried spinal cord were obtained1day,3days,1week,2weeks,3weeks,4weeks and8weeks. The morphological change of Pathological Histology is observed and the expression of nestin was detected by immunofluorescence staining in injuried spinal cord at various time. We found that few of ependymal cells of control group expressed nestin in cytoplasm, and no change of nestin expression occur at various time. The expression of nestin in SCI group was low in1day after spinal cord injury, increased at3day. The expression of nestin in SCI group reached a peak after a week. The expression of nestin reduced after2weeks and was in few cells. In8weeks, the expression of nestin of control group was similar to SCI group(P>0.05). Therefore, we conclude that endogeneous neural stem cell exist in spinal cord tissue. After spinal cord injury, these stem cells proliferate and differentiate in injuried tissue. With time, these stem cells decrease after spinal cord injury.In the second part, we explored the influence of injecting basic fibroblast growth factor or bone morphogenetic protein-2into cerebrospinal fluid on the proliferation of endogeneous neural stem cell in injuried tissue of spinal cord. It will elucidate the effect of the change composition of cerebrospinal fluid on proliferation of endogeneous neural stem cell after spinal cord injury and provided new idea for the treatment of spinal cord injury.60Wistar rats were used and animal model of spinal cord injury was established by clips impressing aneurysm. Wistar rats were divided into4groups (n=15) random:A group was used to inject saline as control, B group injecting bone morphogenetic protein-2, C group injecting basic fibroblast growth factor, D group injecting bone morphogenetic protein-2and basic fibroblast growth factor. The morphological change of Pathological Histology is observed and the expression of BrdU and nestin was detected by immunofluorescence staining in injuried spinal cord at1,2,3,4and8weeks. We found that the number of BrdU-positive cells were equal in each group1week after SCI;2weeks after SCI, the number of BrdU-positive cells decreased in A group and increased in B, C and D group;3weeks after SCI, the number of BrdU-positive cells decreased obviously in A group and reached a peak in B, C and D group;4weeks after SCI, the number of BrdU-positive cells began to decrease in B, C and D group;8weeks after SCI, we found no BrdU-positive cells in A group and a few BrdU-positive cells in B, C and D group. We observed that the expression levels of nestin were detected similarly in each group in1week after spinal cord injury(P>0.05), demonstrating that these injection have no influence on endogeneous neural stem cell;2weeks after SCI, the number of nestin-positive cells decreased in A group and increased in B, C and D group;3weeks after SCI, the number of nestin-positive cells reached a peak in B, C and D group;4weeks after SCI, the number of nestin-positive cells began to decrease in B, C and D group, among which the nestin-positive cells in B group decreased apparently;8weeks after SCI, we found no nestin-positive cells in A group and a few BrdU-positive cells in B, C and D group.So, we conclude that in injuried tissue of rat spinal cord, injecting basic fibroblast growth factor and bone morphogenetic protein-2into Cerebrospinal fluid obviously increased the number of neural stem cells, indicating fibroblast growth factor and bone morphogenetic protein-2promoted proliferation and differentiation of endogeneous neural stem cell. Our results demonstrated that the change of constitute of cerebrospinal fluid can influence proliferation and differentiatin of endogeneous neural stem cell after spinal cord injury.