绿色荧光蛋白基因腺病毒载体转染兔骨髓间充质干细胞的实验*

背景：以骨髓间充质干细胞作为种子细胞,把干细胞和基因治疗结合起来是研究中枢神经系统损伤和肿瘤治疗新的思路和趋势。 目的：观察腺病毒载体绿色荧光蛋白基因(Ad-GFP)在兔骨髓间充质干细胞转染和表达的量效关系及对细胞生物学特性的影响,探讨用该载体构建基因修饰骨髓间充质干细胞的可行性。 设计、时间及地点：随机分组设计,对比观察,于2008-08/2009-03在南方医科大学完成。 材料：新西兰大白兔,雌雄不拘,质量2.0~3.0 kg。 方法：体外分离培养兔骨髓间充质干细胞,流式细胞仪检测细胞免疫表型,293细胞包装制备病毒,以不同滴度的Ad-GFP(1×103~1×1010 PFU/mL)转染骨髓间充质干细胞,细胞计数法分析转染率。 主要观察指标：倒置显微镜观察细胞形态学改变,CCK8法检测细胞增殖活性,用血清撤离加入β-巯基乙醇诱导感染Ad-GFP BMSCs向神经样细胞的定向分化。 结果：3~6代骨髓间充质干细胞表面标志CD34、CD45阴性,而CD29、CD44阳性。当病毒滴度为1×107 PFU/mL时感染率为55%,1×109,1×1010 PFU/mL感染率均为85%,但1×1010 PFU/mL时出现细胞病理现象,7 d荧光表达最强,28 d仍可见荧光表达。感染Ad-GFP的骨髓间充质干细胞经β-巯基乙醇诱导可分化为神经元样细胞,神经元特异性烯醇化酶表达阳性。 结论：合适滴度的Ad-GFP可以高效感染骨髓间充质干细胞,对细胞的生物学特性影响较小,不影响诱导分化功能,骨髓间充质干细胞可以作为Ad-GFP载体系统进行基因治疗研究的种子细胞。     

血红素加氧酶-1基因转染对神经元损伤的保护作用

目的观察腺病毒介导的血红素加氧酶-1（HO—1）基因转染大鼠后对脑缺血再灌注损伤的保护作用。方法雄性SD大鼠随机分为4组：假手术对照组（SH）、生理盐水组（V）、空载体组（Ad）和Ad—HO-1转染组（HO）。后三组在缺血前3d于右侧脑室部分别注射20μl生理盐水、含1μl空载体腺病毒（1．0×10^10plaque-forming unit／ml,PFU／ml）的生理盐水或含1μl重组HO-1腺病毒（1．0×10^10PFU／ml）的生理盐水,连续注射3d后,采用右侧大脑中动脉栓塞法（MCAO）建立脑缺血再灌注模型。每组大鼠测定神经功能后,处死大鼠并取全脑标本,测定右脑梗死体积及细胞凋亡指标,荧光显微镜下观察脑组织荧光蛋白的表达情况,Western blot检测脑组织HO-1的表达。结果HO组中HO-1表达量明显高于Ad组和V组,Ad组和HO组可见有荧光蛋白表达,转染率为34．5％±3．4％。HO组神经功能显著优于Ad组和V组（P〈0．001）。与SH组比较,V组、Ad组脑梗死体积、神经细胞凋亡明显升高。与V组及Ad组比较,HO组脑梗死体积显著减小（P〈0．01）、神经元凋亡显著减少（P〈0．01）。结论腺病毒携带的HO-1基因能有效的转染脑组织,并在脑内稳定表达;HO-1基因转染显著减轻脑缺血再灌注后神经细胞损伤。     

5和5/F35型腺病毒载体对人骨髓间充质干细胞转染效率的比较

背景：在以人骨髓间充质干细胞为基础的基因治疗中，提高腺病毒载体对人骨髓间充质干细胞的转染效率尤为重要。 目的：对比观察5和5/F35型腺病毒载体对体外培养的人骨髓间充质干细胞的转染效率。 设计、时间及地点：对比观察，于2008-03/10在解放军北京军区总医院血液科实验室完成。 材料：骨髓来源于解放军北京军区总医院血液科异基因造血干细胞移植中健康供者，均无造血系统疾病。 方法：采用密度梯度离心和贴壁筛选的方法体外分离培养人骨髓间充质干细胞，传至第3代后用流式细胞仪检测人骨髓间充质干细胞表型；按1×104/孔密度接种于24孔板，细胞贴壁后分别换用成骨、成脂诱导液培养，以碱性磷酸酶、油红O染色检测其分化特性。用不同滴度编码增强型绿色荧光蛋白基因的腺病毒载体Ad5增强型绿色荧光蛋白和Ad5/F35增强型绿色荧光蛋白按5，20，100，400 感染复数转染体外培养的人骨髓间充质干细胞，荧光显微镜下观察。 主要观察指标：流式细胞仪检测增强型绿色荧光蛋白阳性表达率，并用锥虫蓝拒染法检测不同病毒滴度感染后人骨髓间充质干细胞活细胞比例。 结果：人骨髓间充质干细胞表面CD166、CD29、CD73、CD31、CD45、CD34和CD14阳性率分别为95.08%、99.53%、72.26%，1.50%，2.02%，3.80%和4.94%。人骨髓间充质干细胞成骨诱导后14 d碱性磷酸酶染色为阳性，成脂诱导后14 d油红O染色均为阳性。Ad5增强型绿色荧光蛋白和Ad5/F35增强型绿色荧光蛋白按5，20，100，400 感染复数分别感染人骨髓间充质干细胞，2 d后前者增强型绿色荧光蛋白阳性率分别为(0.72±0.14)%，(4.97±0.46)%，(9.80±3.43)%和(45.53±6.32)%；后者增强型绿色荧光蛋白阳性率分别为(24.31±10.55)%，(55.19±13.73)%，(87.68±9.5)%和(96.57±5.64)%。在5，20，100的感染复数，各组细胞存活率均在95%以上。在400的感染复数，细胞存活率明显降低，在90%以下。 结论：Ad5/F35对体外培养的人骨髓间充质干细胞的转染效率明显优于Ad5载体。     

碱性成纤维细胞生长因子-慢病毒真核表达载体的构建及转染

背景：以往研究多采用质粒载体,由于其转染效率不高,且转染时需借助脂质体转染剂进行转染,转染具有细胞毒性,操作复杂等难以应用于临床。 目的：构建携带人碱性成纤维细胞生长因子(basic fibroblast growth factor,bFGF)基因的慢病毒载体,转染成骨方向诱导的骨髓间充质干细胞(bone marrow mesenchymal stem cells,BMSCs),鉴定bFGF基因表达。 方法：实验组：设计人bFGF基因引物,用Trizol法提取胎盘组织RNA,用RT-PCR的方法扩增出bFGF基因,连接至pLenti6/V5-D-TOPO® 表达质粒,经Xho-Ⅰ、BamH-Ⅰ双酶切和DNA测序证实质粒正确构建。在脂质体转染剂Lipofectamine 2000的介导下,将bFGF-pLenti6/V5-D-TOPO表达质粒同包装质粒pLP1、pLP2、 包膜质粒pLP/VSVG 共转染293FT细胞株,收集bFGF-慢病毒上清转染诱导后第2代的兔BMSCs。对照组：设计GFP基因引物,以GFP- PMSLV-Plazmid为模板,PCR的方法扩增出GFP基因,连接至pLenti6/V5-D-TOPO® 表达质粒,构建GFP-慢病毒载体,并转染BMSCs。RT-PCR和Wetern-blot方法检测bFGF、GFP基因的表达。 结果与结论：转染48 h后,对照组BMSCs可见绿色荧光蛋白表达;实验组BMSCs在转染15 d后,RT-PCR方法扩增出bFGF基因,Western-blot检测出目的蛋白表达。提示成功构建携带人bFGF和GFP基因的真核表达载体,建立转染兔BMSCs的方法。     

Neurturin基因在体外培养的大鼠骨髓基质细胞中的表达

目的构建携带一种神经营养因子Neurturin(NTN)基因的腺病毒(Ad),使其在骨髓基质细胞(BMSCs)中表达。方法采用分子克隆技术,构建携带NTN基因的Ad载体,用脂质体法转染、包装HEK293细胞,制备具有感染活性的Ad-NTN病毒粒子;用病毒上清液感染原代培养的大鼠BMSCs,并用免疫细胞化学方法检测阳性细胞。用W estern B lot检测转染Ad-NTN的BMSCs细胞上清液。结果经酶切鉴定和DNA测序,得到重组Ad-NTN,对被感染的HEK293细胞进行病毒滴度测定,每毫升病毒贮存液可达1×108.5半数组织培养感染量(TC ID50);将病毒贮存液感染BMSCs,获得了表达NTN的BMSCs,阳性率为65%。W estern B lot检测证实BMSCs上清液中出现特异性NTN条带。结论重组Ad携带的NTN基因能够在BMSCs中表达。     

转染绿色荧光蛋白的神经干细胞移植于半横断脊髓损伤处的体内外分化研究

目的 观察转染绿色荧光蛋白(GFP)的大鼠脊髓神经干细胞移植于半横断脊髓损伤处的体内外分化情况.方法 将表达GFP的慢病毒载体转染胎鼠脊髓神经干细胞,体外用10%胎牛血清诱导分化.转染后的神经干细胞与PLGA支架移植于大鼠半横断脊髓损伤处,术后1个月和3个月取材,行GFAP、NF和CNP免疫荧光染色.结果 转染GFP的神经干细胞球表达强烈的绿色荧光,体外分化可见GFAP/GFP、NF/GFP和CNP/GFP双阳性细胞,GFAP/GFP双阳性细胞明显多于其他两种.移植后3个月,GFP阳性细胞在脊髓内明显减少,可见少数GFAP/GFP和CNP/GFP舣阳性细胞,未见NF/GFP双阳性细胞.结论 转染GFP的神经干细胞可在体外增殖和分化,但大部分分化成胶质细胞.移植于急性期脊髓损伤处的神经干细胞不被诱导分化成神经元样细胞,可被诱导分化成神经胶质细胞.     

肿瘤坏死因子α对大鼠平滑肌细胞增殖及syndecan-4蛋白表达的影响

目的 观察肿瘤坏死因子α（TNF—α）对大鼠胸主动脉血管平滑肌细胞（VSMC）增殖和syndecan-4蛋白表达的影响。方法 体外培养大鼠胸主动脉VSMC，1、10、20、100ng／mL的TNF—α分别作用并设立对照组（不采取干预措施）进行比较，采用MTS／PES法确定VSMC的增殖状态，利用Western blot蛋白免疫印迹法测定syndecan-4蛋白表达。结果 各组细胞增殖率分别为对照组1．001±0．064，TNF—α 1ng／mL组1．082±0．272，10ng／mL组1．125±0．198，20ng／mL组1．566±0．060，100ng／mL组1．215±0．231。统计分析显示低至1ng／mL的TNF-α仍能明显刺激大鼠VSMC的增殖（与对照组比较，P〈0．05），其中以TNF—α 20ng／mL组细胞增殖最显著。TNF-α对VSMC的syndecan-4蛋白的表达有显著的增强作用（与对照组比较，P〈0．05），其中也以20ng／mL组增强作用最显著。结论 TNF-α对体外培养大鼠VSMC增殖和syndecan-4蛋白表达均有显著的促进作用。     

hTERT正、反义表达载体转染大鼠骨髓间充质干细胞的实验研究

目的研究提高和阻断端粒酶活性对大鼠骨髓间充质干细胞(BMSCs)增殖及分化的影响。方法采用直接贴壁法分离、培养SD大鼠BMSCs,流式细胞仪检测BMSCs表面标记。阳离子脂质体介导hTERT正、反义表达载体转染BMSCs,RT-PCR和免疫组化方法检测TERT表达,并对转染前后BMSCs的生长增殖能力、神经细胞方向的分化能力和大鼠颅内移植存活情况进行研究。结果大鼠BMSCs表面CD29、CD44、CD90阳性,CD31、CD34、CD45阴性,转染正义hTERT后BMSCs增殖速度明显提高,而其向神经元和星形胶质细胞诱导分化及异体海马移植后的存活能力未受影响,转染反义hTERT后BMSCs增殖速度减慢,5￣6周内死亡。结论BMSCs存在端粒酶低表达,提高或阻断端粒酶活性对BMSCs的增殖分别起到促进或抑制作用。     

骨髓基质细胞分化为神经元样细胞后与皮质神经元间突触的建立

目的 观察与大脑皮质神经元共培养的骨髓基质细胞(BMSCs)经诱导分化成神经元样细胞后,与脑皮质神经元之间形成功能性突触的情况.方法 无菌条件下取绿色荧光蛋白(GFP)转基因小鼠骨髓,用贴壁筛选法体外培养获得GFP转基因小鼠BMSCs(GFP-GM-BMSCs),在体外培养、扩增、纯化.取第3代GFP-GM-BMSCs,种植到源于小鼠大脑的原代皮质神经元和胶质细胞中,培养介质为加有20 ng/mL表皮生长因子(EGF)、20 ng/mL碱性成纤维细胞生长因子(bFGF)的无血清培养基(Neurobasal-A+2%B27),体外模拟建立细胞移植的共培养体系.共培养第10天,利用FM1-43荧光染料染色活动突触小泡的特性,通过荧光显微镜观察共培养的两种细胞之间形成的突触.结果 与神经元共培养的GFP-GM-BMSCs在含有EGF、bFGF的无血清培养基中7 d后分化为神经元样细胞.共培养10 d后,FM1-43染色阳性的突触囊泡明显增加,主要位于神经元样细胞胞体、突起及其末端结构上.结论 在体外模拟细胞移植共培养体系中,分化自GFP-GM-BMSCs的神经元样细胞能与神经元之间形成突触样连接.     

HIV-1来源的慢病毒载体转染大鼠脊髓神经干细胞

目的 介绍人类免疫缺陷病毒（Human immunodenciency virus-1，HIV-1）载体的构建技转染大鼠脊髓神经干细胞的实验方法。方法 将含有绿色荧光蛋白（green fluorescence protein，GFP）的4种质粒通过293T细胞构建成GFP—HIV载体。用Elisa法及Hela细胞分别验证其高浓度技强感染力后将其转染大鼠脊髓神经干细胞。结果 GFP—HIV载体浓度达56672．93pg／ml，荧光显微镜FHela细胞胞浆内充满深浅不一的绿荧光，大鼠脊髓神经干细胞球发强烈的绿荧光：结论此实验方法操作简单、快捷，具有高效性及安全性。HIV载体将是基因治疗的理想工具。     

Diagnostic Difficulties and Treatment Implications

Summary: Differentiation between types of epileptic seizures has been aided in recent years by the introduction of intensive neurodiagnostic techniques and the development of increasingly detailed classification systems. Paradoxically, these developments have not simplified the task of matching the appropriate antiepileptic drug to a particular seizure type. It is reasonable to assume that anticonvulsant drugs will have different effects on different types of seizures, but faulty, circular reasoning can enter the picture if one also assumes that responses of seizures to different drugs signify different seizure types. There are several examples of differential diagnoses that can fall prey to this problem, including the diagnosis between partial seizures with secondary generalization and generalized tonic-clonic seizures, and the diagnosis between complex partial seizures and absence seizures with automatisms, among others. Considerations of etiology in future classification systems can further complicate the problem: should one then choose an anticonvulsant drug on the basis of individual seizure type or on the basis of the type of epilepsy? Ramifications of this issue extend even to the drug approval process. Official sanction is not given for use of a drug for a seizure type not included in the original efficacy studies, even if later scientific evidence shows that seizure type to be related to a type that is included. New trials must be undertaken. These problems arise from how we choose to classify seizures.     

Cognitive Dysfunction Associated with Antiepileptic Drug Therapy

Summary: Epilepsy is frequently associated with cognitive dysfunction. However, the reasons for this correlation are unclear. Possible influential factors include patient age; duration, frequency, etiology, and type of seizures; hereditary factors; psychosocial issues; and antiepileptic drug (AED) therapy. Whereas many of these factors are beyond the physician's control, AED therapy is one element that can be addressed in treatment decisions by recognizing the potential cognitive effects of particular AEDs. For example, phenobarbital impairs memory and concentration; phenytoin affects attention, problem solving ability, and performance of visuomotor tasks. In contrast, carbamazepine may affect concentration, while valproate would appear to have minimal effects on cognition. Moreover, cognitive effects of AEDs are amplified with coadministration of multiple anticonvulsants (polytherapy). A review of studies on the cognitive effects of monotherapy with AEDs, as opposed to those of polytherapy, provides evidence that drug-related cognitive dysfunction can be reversed if patients are switched to a simpler therapeutic regimen. Future research should be directed toward developing reliable measures for assessing and monitoring cognition, and understanding the particular cognitive side effects of each AED. Physicians also need to revise their opinions about which side effects are "tolerable" for epileptic patients.     

Carbamazepine Efficacy in Adults With Partial and Generalized Tonic-Clonic Seizures

Summary: Carbamazepine and phenytoin are drugs of choice in initial monotherapy for adult partial and secondarily generalized tonic-clonic seizures. These designations reflect the results of the Veterans Administration Epilepsy Cooperative Study Group of 1985. An earlier comparative study of carbamazepine and phenytoin by Ramsay and associates found both drugs equally effective in controlling new-onset seizures. Among the advantages of carbamazepine is that it causes relatively few cognitive and dysmorphic side effects. Its disadvantages are its unavailability in parenteral formulation and its metabolic autoinduction. The latter must be compensated for by planned dosage increases to maintain therapeutic plasma steady-state levels during the first 2 or 3 months of treatment. Carbamazepine is judged a drug of choice in the treatment of these secondarily generalized tonic-clonic seizures, and the drug of choice in children, adolescents, and women susceptible to the dysmorphic side effects associated with other anticonvulsant agents.     

Etiologic and Preventive Aspects of Epilepsy in the Child–Bridging the Gap Between Laboratory and Clinic

Summary: Four broad categories of basic phenomena are pertinent to developing ways to prevent epilepsy. These include mechanisms of epileptogenesis, ictal initiation and temporary entrainment by the seizure discharge of normally functioning brain, seizure propagation, and control mechanisms that function both to restrain the cascade of epileptic events culminating in a seizure and to arrest the epileptic event and restore the interictal state. In newborns and children, hypoxia-ischemia is a major factor leading to epileptogenesis, and several schemes are proposed to classify, quantify, and prevent hypoxic-ischemic encephalopathy. Control mechanisms must be better understood in order to develop prophylactic recommendations for epilepsy, and an experimental model of "kindling antagonism" may increase our understanding of these. Programs of prevention of seizures in children will evolve only if basic researchers and clinicians work productively together to develop an adequate understanding of factors important in epileptogenesis and antiepileptogenic control mechanisms.     

Treatment Considerations in Anticonvulsant Monotherapy

Summary: The long-standing practice of polypharmacy in treating epilepsy is giving way to use of monotherapy. Monotherapy can improve seizure control as well as reduce the risk of serious idiosyncratic reactions, dose-related side effects, and complex drug interactions. Monotherapy also offers improved compliance and cost-effectiveness. The basis of monotherapy is accurate diagnosis and assessment of the patient's seizure type(s), followed by selection of a single appropriate anticonvulsant drug. Many patients currently treated with multiple anticonvulsants can be successfully converted to monotherapy with a carefully monitored program in which troublesome and redundant drugs are gradually withdrawn from the therapeutic regimen.     

Predisposing and Causative Factors in Childhood Epilepsy

Summary: We review information from large studies of defined populations, examining the role of known factors and especially of prenatal and perinatal factors in contributing to nonfebrile seizure disorders of early childhood. We depend especially, but not exclusively, on the recently completed analyses from the Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke, the NCPP. About 4% of children in the NCPP who had at least one non-febrile nonsymptomatic seizure by the age of 7 years had a previous seizure during acute neurologic illness, such as meningitis or during the acute illness after trauma. Many such seizures should potentially be preventable. Of children with seizures, 10% had had a neonatal seizure and 13% had had a febrile seizure. Among the hundreds of prenatal and perinatal factors explored as predictors of childhood seizure disorders, the principal predictors identified were congenital malformations of the fetus, cerebral and noncerebral; family history of certain neurologic disorders; and neonatal seizures. In agreement with the British National Child Development Study, labor and delivery factors in the NCPP appeared to contribute very little to childhood seizure disorders. Maldevelopment, rather than damage at birth to an initially intact nervous system, appeared to be the more common mechanism. Most seizure disorders of early childhood remained unexplained by the large set of prenatal and perinatal characteristics examined.     

Dextromethorphan: Cellular Effects Reducing Neuronal Hyperactivity

Summary: Dextromethorphan is a dextrorotary morphinan without affinity for opioid receptors, commonly used as an antitussive medication. During the past 5 years, interest in the compound and its demethylated derivative, dextrorphan, has been revived because additional neuroprotective and an-tiepileptic properties were found in in vitro studies, animal experiments, and a few clinical cases. Both morphinans are able to inhibit N -methyl-D-aspartate (NMDA) receptor channels and voltage-operated calcium and sodium channels with different potencies. The inhibition of the NMDA receptor is believed to be the predominant mechanism of action responsible for the anticonvulsant and neuroprotective properties of the compounds.     

Anticonvulsant Drugs and Cognitive Function: A Review of the Literature

Summary: Alterations of cognitive function are separate from disturbances of behavior seen in association with epilepsy. The nature of the cognitive disability may to a certain extent depend on the seizure type. Partial seizures, mainly derived from a temporal lobe focus, impair memory tasks, while generalized seizures seem to have more effect on attentional abilities. A number of studies, reviewed in this paper, suggest that anticonvulsant drugs further impair cognitive function. Maximal impairments are seen in patients receiving polytherapy: rationalization of polytherapy improves cognitive abilities. Studies in children and adults have allowed differentiation of the effects of various commonly used antiepileptic agents. Maximal cognitive deficits are seen with. phenytoin, while phenobarbital and sodium valproate induce moderate disturbances, and carbamazepine seems relatively free from such toxicity. Further research is needed on the interrelationship between types of seizure disorders, types of anticonvulsant medications, and cognitive function.     

Effects of NMD A- and AMPA-Receptor Antagonists on Different Forms of Epileptiform Activity in Rat Temporal Cortex Slices

Summary: Lowering extracellular magnesium induces different patterns of epileptiform activity in rat hippocampus and entorhinal cortex. Short recurrent epileptiform discharges in the hippocampus are stable over time, whereas seizurelike events (SLEs) in the entorhinal cortex, the subiculum, and the neighboring neocortex develop into late recurrent discharges which are not blocked by clinically employed antiepileptic drugs. We tested the sensitivity of the different epileptiform discharge patterns to. /V-methyl-D-aspartate (NMDA)- and non-NMDA-receptor antagonists. As NMDA-receptor antagonist we used dextrorphan, ket-amine, and 2-aminophosphonovalerate (2APV); as α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA)-receptor antagonist we employed the quinoxaline derivative glutamate 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). The findings show that the different patterns of epileptiform activity, including the late recurrent discharges, are sensitive to all NMDA-receptor antagonists. However, when dextrorphan was employed to suppress seizure-like events, later recurrent discharges did not develop during the remaining time course of the experiment. CNQX reversibly suppressed recurrent discharges in the hippocampus and SLEs in the entorhinal cortex. However, late recurrent discharges become insensitive to CNQX, even at a high concentration of 60 μM m. This finding suggests a prominent role for NMDA receptors in the generation of late recurrent discharges.     

Pediatric Epilepsy Surgery

Summary: The use of implantable arrays of epidural electrodes has made it possible to carry out extraoperative electrocorticography (ECoG) and functional localization in the awake child. This has permitted cortical excisions that are determined by criteria similar to those obtained during surgical procedures performed under local anesthesia in adults. In addition, the method also permits simultaneous ECoG and video monitoring during the child's symptomatic seizures, providing additional important localizing information that is impractical to obtain in operations under local anesthesia. We report our experience with 75 children, ages 5 months to 15 years, whom we have managed with epidural electrode arrays. The method of extraoperative ECoG is described and illustrative cases are presented to demonstrate its feasibility and utility in children. In addition, we call attention to gliomas as a common cause of chronic focal seizures in children. Of 49 children undergoing resection and followed for from 1 to 14 years (mean of 5.8 years), 32 (65%) are either seizure free or have had a significant reduction in seizure frequency that has unambiguously improved their quality of life. The results are analyzed further by relating the surgical outcome to each of the pathologic entities that caused the seizures. This analysis reveals the variety of neurological conditions that commonly cause intractable focal seizure disorder in children and distinguishes those pathologic entities in which the seizure disorder is apt to respond to surgical intervention from those that will not.