Objective To investigate the division, prol iferation and differentiation abil ities of nestin+/GFAP+cell after spinal cord injury and to identify whether it has the characteristic of neural stem cells (NSCs). Methods Twelvemale SD rats, aged 8 weeks and weighing 200-250 g, were randomized into 2 groups (n=6 per group): model group inwhich the spinal cord injury model was establ ished by aneurysm cl ip compression method, and control group in which no processing was conducted. At 5 days after model ing, T8 spinal cord segment of rats in each group were obtained and the gray and the white substance of spinal cord outside the ependymal region around central tube were isolated to prepare single cellsuspension. Serum-free NSCs culture medium was adopted to culture and serum NSCs culture medium was appl ied to induce differentiation. Immunohistochemistry detection and flow cytometry were appl ied to observe and analyze the type of cells and their capabil ity of division, prol iferation and differentiation. Results At 3-7 days after injury, the model group witnessed a plenty of nestin+/GFAP+ cells in the single cell suspension, while the control group witnessed few. Cell count of the model and the control group was 5.15 ± 0.71 and 1.12 ± 0.38, respectively, indicating there was a significant difference between two groups (P lt; 0.01). Concerning cell cycle, the proportion of S-phase cell and prol iferation index of the model group (15.49% ± 3.04%, 15.88% ± 2.56%) were obviously higher than those of the control group (5.84% ± 0.28%, 6.47% ± 0.61%), indicating there were significant differences between two groups (P lt; 0.01). In the model group, primary cells gradually formed threedimensional cell clone spheres, which were small in size, smooth in margin, protruding in center and positive for nestin immunofluorescence staining, and large amounts of cell clone spheres were harvested after multi ple passages. While in the control group, no obvious cell clone spheres was observed in the primary and passage culture of single cell suspension. At 5 days after induced differentiation of cloned spheres in the model group, immunofluorescence staining showed there were a number of galactocerebroside (GaLC) -nestin+ cells; at 5-7 days, there were abundance of β-tubul in III-nestin+ and GFAP-nestin+ cells; and at 5-14 days, GaLC+ ol igodendrocyte, β-tubul in II+ neuron and GalC+ cell body and protruding were observed. Conclusion Nestin+/GFAP+ cells obtained by isolating the gray and the white substance of spinal cord outside the ependymal region around central tube after compressive spinal cord injury in adult rat has the abil ity of self-renewal and the potential of multi-polarization and may be a renewable source of NSCs in the central nervous system.
Objective To explore the expression of nestin and glialfibrillary acidic protein (GFAP) at different time and sites after spinal cord injury in adult rats. Methods Seventy-two adult Sprague-Dawley rats, aging 8 weeks and weighing from 180 to 220 g, were randomly divided into 11 experimental groups(66, n=6) and 1 control group(n=6). In the experimental groups, the rat spinal cord injury models were established by aneurysm clip compression, and the expression and proliferation of nestin and GFAP at different time（1 day,3 days, 5 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks,7 weeks and 8 weeks）and at different sites(injured site and adjacent site) were observed with toludine blue staining, immunofluorescent staining and the analytical system of photographs. In control group, the same site of the rat spinal cord was exposed without aneurysm clip compression. The same preparation and examination were done as the experimental groups. Results Toluidine blue staining results showed thatcontour of neurite and pericaryon were distinct and nucleus were deep blue in normal control rats. One day after injury, the number of big and medium-sized neuron decreased obviously; neurite was deep blue with clouding Nissl bodies and ellipse or triangular typed nucleus. In the normal control group, the expression of nestin was hardly seen except ependymal cells of central canal, and the low expression of GFAP was seen. In the experimental groups, the nestin and GFAP expressions increased obviously in the injured sites and adjacent sites 24 hours after injury, reached the peak value after 3-7 days and followed by gradual decrease. There were statistically significant differences in the nestin and GFAP expressions between theexperimental groups and the control group.Conclusion The aboveresults suggestthat spinal cord injury can induce the expression of nestin and GFAP. There is a positive correlation between nestin expression and the proliferation of the reactive astrocytes.