Objective To explore whether the neural stem cells(NSCs) can act directly as a gene target cell which can be infected by the recombinant retrovirus and express the products of exogenous genes after infection. Methods The NSCs were cultured with supernatant containing the recombinant retroviruses with the genes of NGF or GDNF for two days.After screened with G418,the infected NSC were expanded at the present of bFGF in culture.The PC12 cells and the neurons of ventral midbrain of rat were cultured by the medium from the infected NSC,which were called as GDNF\|containing conditioned medium NGF or GDNF\|containing conditioned medium the morphological changes of the dopamine neurons of the ventral midbrain and expression of exogenous genes of the infected NSCs were detected by immunohistochemistry staining. Results It was estimated that about fifty percent of NSCs via retrovirus\|mediated NGF or GDNF gene transduction were G418\|resistant.These infected NSCs began to differentiate.Long and radical processes reached out from the sphere of proliferation and the cells migrated towards outside along the processes.The NSC infected with gene of NGF showed an astroid\|shape with larger body and processes.The NSC infected with gene of GDNF showed a shuttle\|shape with a smaller body and long processes.The PC12 cells increased in the NGF\|containing conditioned medium and stretched out long neurites.The dopamine neuron of the ventral midbrain which were immunoreactive for TH also showed a larger body and longer processes in the GDNF\|containing conditioned medium.Most of G418\|resistant NSCs were immunoreactive for NGF or GDNF. Conclusion NSC can act directly as a gene target cell which not only be infected by the recombinant retrovirus,but also express and secrete the products of exogenous genes.

In order to investigate effect of basic fibroblast growth factor(bFGF) on the prolifiration and differentiation of theneural progenitor of embryonic hippocampus of rats in vitro, 25 ng/ml bFGF was employed into the serum-free medium of cultureof hippocampal neural cells of embryonic day 18 rats in the present study. The effect of bFGF on the viability of cells culturedwas detected by MTT colorimetric method and the effects of bFGF on proliferation and differentiation of hippocampal neural pro-genitors were analyzed qualitatively and quantitatively by means of immunochemistry, for the nestin, neurofilament, galactocere-broside and glial acidic fibrillary protein. The results showed that the OD value of experimental group was higher than that ofcontrol group by 1.5 and 1.8 times at 4 d and 8 d respectively. The quantitative analysis of each kinds of cells indicated that thenumber of neural progenitors, neurons and oligodendrocytes in experimental group were increased about 2 times as many as thatin control group, but no differences of astrocytes between the two groups at 4 d. However, the number of four kinds of cells aug-mented about 1.7 times at 8 d. The results of this study suggest that bFGF can not only promote the survival, proliferation, butalso facilitate the differentiation of neural progenitor of hippocampus to neurons and glial cells. To obtain more many purifiedneural progenitors in vitro, the embryonic day 18 is not an appropriate age. It is better to get younger embryo brain to culture and to add enough bFGF.

Objective To investigate the survival,differentiation and gene expression of the neural stem cells(NSCs) modified by the gene of NGF or GDNF in the brain of AD rat model after transplantation. Methods The NGF or GDNF genetically modified NSCs labled with BrdU were implanted into the lateral cerebral ventricle of the AD rat model.The rats were killed three weeks after transplantation.The brains were cut and the sections were processed for single or double immunochemistry staining with antibodies against BrdU,Nestin,GFAP,NF,NGF and GDNF. Results BrdU\|positive cells were found in the lateral cerebral ventricle.Some of them migrated into the parenchyma and located in the wound,fibria\|fonix,hippocampus,corpus callosum,septum,subventricle zone and beside the blood vessels.Cells of doubled labeling with anti\|BrdU and GFAP were more often seen in the cortex,whereas more cells with anti\|BrdU and NF in the hippocampus,and both of them in the ventricle.Doubled labeling cells against BrdU and NGF,and against BrdU and GDNF were found in the ventricle and parenchyma.Conclusion\ The NGF or GDNF genetically modified NSCs can not only survive well,but also differentiate into neuron and astrocyte,and express the exogenous genes of NGF and GDNF in the host brain

Objective To investigate the effect of a single or combined transplantation of the neural stem cells(NSCs) modified with gene of NGF or GDNF on the cholinergic neurons of basal forebrain of AD model rat. Methods The NSCs modified with gene of NGF or GDNF were implanted in single or combined into the lateral cerebral ventricle of the rats after fibria\|fornix transection.The rats were killed three weeks after transplantation and the brain sections concluding basal forebrain were cut coronally on a freezing microtome and were processed by immunohistochemistry staining with antibodies against ChAT.The numbers of ChAT positive neurons of medial septum(MS) and vertical diagonal band(VDB) were analyzied statistically with one way of Student\|Newman Kaels. Results In MS,the percentages of ChAT positive neurons at the lesion side to the intact side in NGF group was 81% which was significantly higher than that in the lesion group(34%),NSC group(36%) and GDNF group(50%), P 0\^05). Conclusion\ The injury cholinergic neurons can be protected in different extent after a single or combined transplantation of the neural stem cells modified with gene of NGF or GDNF.Among these three groups,greater protection was found in NGF group and NGF+GDNF group,and lesser protection in GDNF group.\;[

Objective To investigate the memory amelioration of the AD model rat after a single or combined transplantation of the neural stem cells(NSCs) modified with gene of NGF or GDNF. Methods The AD model rat was made by cutting unilaterally the fibria\|fornix of male SD rat.Eight to ten days after surgery,the genetically modified and unmodified NSCs were implanted into the lateral cerebral ventricle of the rats.Two weeks after transplantation,the amelioration of memory impairment of the rats were detected by Morris water maze. Results The average escape latencies of the last three blocks in NGF and NGF+GDNF groups were lesser,and the percentages of swim distance in the platform quadrant were greater than that in NSC group( P

Through genetic recombination technique, the rat glial cell line-derived neurotrophic factor (rGDNF) cDNA was in-serted into polylinker site of retroviral vector pLXSN, to generate a recombinant plasmid pLXSN-GDNF as transfer vector. Therecombinant plasmid was verified with restriction analysis, PCR, dot blot hybridization and Southern blot hybridization. The re-sults showed that GDNF cDNA was cloned correctly into retroviral vector pLXSN, recombinant retroviral vector was construct-ed. It is concluded that the eukaryotic cell expression vector was constructed successfully for gene therapy of Parkinson's,Alzheimer's and other central nervous system diseases.

Objective To investigate the clinical effect of posterior short-segment pedicle screw reduction and fixation without fusion in treatment of thoracolumbar mono-segmental compression fractures.Methods Thirty cases of thoracolumbar mono-segmental compression fractures admitted from January 2009 to February 2010 were assigned to single posterior pedicle screw fixation (screw group,n =15) and posterior pedicle screw fixation with posterolateral fusion (fusion group,n =15) according to random number table.Clinical results in the two groups were assessed based on Cobb' s angle,anterior vertebral body height ratio (％) and Oswestry disability index (ODI) before operation,after operation,prior to the removal of implant and at the latest follow-up.Results All the cases were followed up for average 24 months.Both operation time and blood loss were less in screw group than in fusion group [(76.58 ±12.67) min vs (116.29 ± 17.45) min,P ＜ 0.01 ; (287.54 ± 30.76) ml vs (480.34 ± 100.54) ml,P ＜0.01],whereas there were no statistical differences between the two groups in aspects of Cobb' s angle and anterior vertebral body height ratio before and after operation,prior to the removal of implant as well as at the latest follow-up.Moreover,no statistical difference of ODI was noted between the two groups prior to the removal of implant and at the latest follow-up.Conclusion Posterior pedicle screw fixation without bone grafting achieves similar effects with pedicle screw fixation with bone grafting.

Objective:To compare the restoration effects and mechanical reconstruction between different approaches in percutaneous kyphoplasty (PKP) through an in vitro mechanical experiment. Methods:T 7 to L 4 segments of adult male embalmed spinal specimens were selected for this experiment. Single vertebral specimens were randomly divided into 4 groups: unilateral angled approach group (Group A), unilateral transpedicular approach group (Group B), unilateral oblique approach group (Group C), and bilateral transpedicular approach group (Group D) ( n=10). The anterior and posterior edges of the vertebral body were measured, and the vertebral volumes were calculated and compared. After the model of osteoporotic vertebral compression fracture (OVCF) was established on a biomechanical machine, the anterior and posterior edges of the vertebral body were measured again. After the 4 groups of specimens were subjected to PKP via different approaches, Micro-CT examination of the vertebral bodies was conducted to measure the postoperative anterior and posterior edges of the vertebral body. The original strength and stiffness of the vertebral body, the stiffness after modeling, the postoperative strength, the postoperative stiffness on the puncture and contralateral sides, and postoperative overall stiffness were recorded. The distribution of bone cement in the vertebral body, recovery of anterior and posterior heights, strength, and stiffness were compared among the 4 groups. Results:There was no statistically significant difference in the vertebral volume among the 4 groups ( P>0.05). The amount of bone cement in group D was significantly larger than that in the other 3 groups ( P<0.05). There was no statistically significant difference among the 4 groups in terms of vertebral height recovery, original strength, original stiffness, stiffness after modeling, or postoperative overall stiffness ( P>0.05). There was no statistically significant difference between the postoperative strength and the original strength in the 4 groups ( P>0.05). The postoperative stiffness on the puncture side in the 4 groups and the postoperative stiffness on the contralateral side in groups A and D were significantly higher than those after modeling ( P<0.05), but there was no statistically significant difference in the contralateral stiffness in groups B and C between postoperation and post-modeling ( P>0.05). Conclusions:In PKP, the unilateral angled approach, unilateral transpedicular approach, unilateral oblique approach, and bilateral transpedicular approach all can effectively restore the height, strength and overall stiffness of the responsible vertebral body. The unilateral angled approach and the bilateral transpedicular approach can achieve balanced restoration of the stiffness on bilateral sides of the responsible vertebral body.