BACKGROUND: Previous studies have demonstrated that neural stem cells play potential therapeutic effects on the repair of spinal cord injury. However, the time for acquiring the best allotransplantation effects remains unclear.OBJECTIVE: This study was designed to observe the repairing effects of allotransplantation of embryonic neural stem cells on the motor function of rat two posterior limbs after spinal cord injury and investigate the time effectiveness of the allotransplantation.DESIGN: A controlled observational experiment.SETTING: Laboratory of Molecular Biology, Dalian Medical University; Laboratory of Biomedicine, School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian, Liaoning Province, China.METHODS: This study was performed at the Laboratory of Molecular Biology, Dalian Medical University & Laboratory of Biomedicine, School of Environmental and Biological Science and Technology, Dalian University of Technology between July and August 2003. One albino rat of gestational 14-16 days was sacrificed for harvesting embryonic rat brain cells. Embryonic rat cerebral cortex and subcortical periventricular brain tissue were taken for in vitro culture of rat embryonic neural stem cells. An additional 30 adult Sprague Dawley rats were randomly divided into 3 groups with 10 rats in each group: control, early allotransplantation and delayed allotransplantation groups. All 30 rats were subjected to spinal cord transection injury, leading to rat paralysis of both lower extremities. Embryonic rat neural stem cells were transplanted into the rats in the early and delayed transplantation groups at 3 days and 3 weeks after injury, respectively. Following allotransplantation, motor function of rat two lower extremities was followed. At 4 weeks after allotransplantation of neural stem cells, rat spinal cord was harvested from transplanted region for immunohistochemistry in order to observe and compare the morphological change of rat spinal cord tissue among the 3 groups. The following protocol was performed in accordance with ethical guidelines stated in Guide for the use and care of laboratory animals, approved by the Committee on the Care and Use of Laboratory Animals of the Institute of Laboratory Animal Resources Commission on Life Scineces, National Research Council, China (1985).MAIN OUTCOME MEASURES: Motor functional recovery of rat two lower extremities after neural stem cell transplantation. Histomorphological change of rat spinal cord at 4 weeks after neural stem cell transplantation.RESULTS: Thirty rats were included in the final analysis. In the early and delayed transplantation groups, the motor function of rat two lower extremities was noticeably improved, in particular in the early transplantation group. In the two experimental groups, muscular strength of paralyzed rat two lower extremities began to recover 5 or 6 days after transplantation of neural stem cells. Two or three weeks later, all rats in the two experimental groups could crawl and four weeks later, two extremities could move actively (approximately approaching to score 3 prescribed as follows). In the control group, no recovery of paralyzed extremities was found. At 4 weeks after transplantation, in the early transplantation group, proliferative tissue could be visible in the spinal cord transplantation region. Through the use of microscope, a considerable number of new cells were found that presented with neuronal and glial cell-positive staining. In the control group, a cavity between two broken ends could be visible. Meanwhile, necrosis and vacuolar degeneration, and other symptoms in the stump of spinal cord were observed with a microscope. In the delayed transplantation group, the histomorphological change of spinal cord region was between the other two groups. No typical histomorphological change was found. A number of new cells were apparent with a microscope, but the number was less compared with the early transplantation group.CONCLUSION: Allotransplantation of embryonic neural stem cells promotes the recovery of rat motor function after spinal cord transection. Early transplantation acquires better therapeutic effects.

BACKGROUND: Bone marrow mesenchymal stem cells (BMSCs) are easily isolated and amplified, and facilitate the exogenous gene transfer and expression. In the human medicine, it is believed that BMSCs are ideal therapeutic cells and target cells in the gene therapy.OBJECTIVE: To investigate liposome-mediated cytosine deaminase (CD) gene transfecting rabbit BMSCs and its gene expression. DESIGN: A single sample observation. SETTING: Dalian Research and Development Center for Stem Cell and Tissue Engineering; Department of Biochemistry, College of Basic Medical Science, Dalian Medical University.MATERIALS: This study was performed at in the Dalian Research and Development Center for Stem Cell and Tissue Engineering; Department of Biochemistry, College of Basic Medical Science, Dalian Medical University from March 2006 to June 2007. New Zealand big-ear white rabbits of either gender, weighing 2.0-2.5 kg, with the age of 5 months old, were included in this study. METHODS: The CD gene was obtained from E.coli JM109 DNA by polymerase chain reaction (PCR). The fragment was cloned into pMD19-T vector. After restriction enzyme BamHI/XhoI digestion analysis and DNA sequence analysis, pIRES2-AcGFP1-CD eukaryotic expression plasmid was constructed. Meanwhile, BMSCs were harvested, cultured and identified. After enzyme digestion of eukaryotic expression plasmid, the rabbit BMSCs were transfected by Lipofectamine 2000-mediated method. Twenty-four hours after transfection, expression of green fluorescent protein was observed under an inverted fluorescent microscope. MAIN OUTCOME MEASURES: Construction of eukaryotic expression plasmid and identification of CD gene-transferred BMSCs. RESULTS: CD gene was cloned and connected to eukaryotic expression plasmid with green fluorescence. Twenty-four hours after transfecting rabbit BMSCs, it was found under an inverted microscope that under the excitation of 488 nm blue light, green fluorescence appeared in the pIRES2-AcGFP1-CD and pIRES2-AcGFP1 empty-plasmid transfected BMSCs, but not in the non-transfected ones. It indicates that CD gene successfully transferred BMSCs. CONCLUSION: BMSCs are ideal vectors in the CD gene therapy.