造血干细胞的基因转移及其表达的实验研究

为探索一种安全、有效、简易的非病毒基因转移策略用于介导造血干细胞基因转移的可行性,本研究利用商品化的脂质体将两个标志基因(Neo R和Lac Z)共转导造血细胞。通过G418筛选、富集转导阳性细胞,观察了外源基因在小鼠原代骨髓细胞的基因转移率及其表达的稳定性。结果显示:通过脂质体介导,外源基因在小鼠骨髓细胞可获得有效的瞬时和稳定的表达。同时,经G418筛选,转导阳性细胞可得到明显的富集。提示利用脂质体这一非病毒载体个导造血干细胞基因转移的可行性。     

反义P^53基因和mdm2基因对裸鼠致瘤性的影响

目的;研究反义Ｐ＾５３基因和ｍｄｍ２基因对裸鼠致瘤性的影响,为肺腺癌基因治疗提供新思路和新方法。方法：将含有反义Ｐ＾５３基因和ｍｄｍ２基因及空载体的逆转录表达载体通过脂质体介导分别转染ＧＬＣ－８２细胞,经Ｇ４１８筛选得到抗性克隆。采用流式细胞仪测定细胞周期,软琼脂培养集落形成试验观察集落形成。     

重组人造血干细胞因子基因在人造血干／祖细胞的转移和表达

目的：拓展造血干细胞因子（ＳＣＦ）的研究和基因治疗途径。方法：利用基因重组技术，构建了编码可溶性人ＳＣＦ基因的逆转录病毒载体ｐＬＸＳＮ－ＳＣＦ，应用脂质体ｌｉｐｏｆｅｃｔｉｎ基因转移法将重组质粒导入Ψ２和ＰＡ３１７病毒包装细胞，经Ｇ４１８选择性培养基筛选，获得产重组病毒的包装细胞ＰＡ３１７／ＳＣＦ，其病毒效价为（２．４～８．５）×１０５ＣＦＵ／ｍｌ，继而感染人造血干／祖细胞。应用多聚酶链反应、ＡＰＡＡＰ免疫组化染色和化学发光－直接酶标法检测人ＳＣＦ基因在细胞中转移和表达。结果：逆转录病毒载体介导的ｒｈＳＣＦ基因在人造血干／祖细胞中获得有效转移和表达。结论：为进一步研究ＳＣＦ的生物学特性及开展干细胞移植等提供了一定的途径。     

人白细胞介素6基因转移的成纤维细胞对自然杀伤活性的增强作用

应用磷酸钙共沉淀法将人白细胞介素６（ＩＬ－６）基因转入成纤维细胞ＨＩＨ３Ｔ３，经Ｇ４１８抗性筛选和有限稀释法，从１２株阳性细胞克隆中选出一株高分泌ＩＬ－６克隆（代号为Ｔ６．６）。Ｔ６．６培养上清能显著增强自然杀伤（ＮＫ）活性，当与ＩＬ－２合用时增强效果更佳，抗ＩＬ－６单抗能阻断这种增强作用。将Ｔ６．６大量扩增后植入小鼠腹腔，４８小时后血清中可检测出较高水平的ＩＬ－６，且脾细胞ＮＫ活性比对照组显著升高。实验结果表明，人ＩＬ－６基因转移的成纤维细胞在体内、外均能显著增强ＮＫ活性，提示成纤维细胞介导的ＩＬ－６基因疗法可应用于抗肿瘤、抗感染和造血功能重建等。     

阳离子脂质体介导rhBMP-2基因转染兔骨髓基质干细胞体外分化成骨活性的实验

目的：探讨阳离子脂质体介导的重组人骨形态发生蛋白(Adv-rhBMP-2)基因对兔骨髓基质干细胞(marrow mesenchyrmal stemcells，MMSCs)体外成骨活性的影响。方法：2002-05／07在解放军总医院骨科研究所完成。脂质体介导的基因转染和检测方法：pEGFP-rhBMP-2的扩增．浓度及纯度鉴定。①脂质体包裹质粒DNA，转染MMSCs后测定转染率。②检测rhBMP-2，碱性磷酸酶(ALP)和Ⅰ型胶原的表达。结果：脂质体介导的基因转染后的检测结果：①脂质体介导pEGFP-rhBMP-2转染．MMSCs后所测定的最大转染率为14．18％。②pEGFP-rhBMP-2转染的MMSCs中rhBMP-2，ALP和Ⅰ型胶原的表达呈阳性，而pEGFP转染的细胞和未染细胞rhBMP-2，ALP和Ⅰ型胶原的表达弱阳性。结论：①MMSCs是一种较理想的骨组织工程种子细胞。②脂质体介导质粒rhBMP-2的基因转移安全性好，但转染率相对较低，随着新一代高转染率脂质体的问世，这种治疗方法有望率先进入临床。     

逆转录病毒载体介导PIG—A基因在突变型K562细胞中的表达

目的应用逆转录病毒载体将PIG-A cDNA转导至突变型K562细胞中,观察是否能够逆转K562细胞CD59的表达。方法采用PCR方法从质粒pEBPIG-A中扩增PIG-A基因片断,BamH I及Xho I双胁切后连接至逆转录病毒载体pLEGFP-C1相应位点。脂质体法转染PA317包装细胞,收集病毒上清感染突变型K562细胞,流式细胞仪测定感染前后CD59的表达情况。结果重组逆转录病毒载体转染PA317包装细胞后,24～48h荧光显微镜下观察到绿色荧光蛋白的表达。G418筛选后,病毒滴度测定达(1．6±0．2)×10~4CFU/mL。感染K562细胞前后测定CD59的表达率分别为4．5％±0．7％及21．3％±0．3％(P＜0．01)。结论成功构建了PIG-A基因逆转录病毒载体,感染突变型K562细胞后可以提高其CD59的表达。     

新型白蛋白微泡经超声介导破裂促进EGFP基因在Cos-7细胞的表达

目的：根据超声介导白蛋白微泡破裂空化效应可以增加真核细胞膜对大分子(如DNA)通透性的原理，探讨一种新的转基因方法，以便安全有效和定向地转移目的基因。方法：实验中选择绿色荧光蛋白基因EGFP为标记基因，以自制的白蛋白微泡为载体，用超声介导微泡破裂的方法在体外进行Cos—7细胞的基因转化，同时以脂质体为对照，激光共聚焦显微镜和流式细胞计数仪分别定性和定量观察细胞转化效率。锥虫蓝染色观察细胞的活性。结果：体外试验发现0．8MHz、1．0W／cm^2、10％占空比(dutycycle)、60s超声介导10％白蛋白微泡破裂可以有效稳定地转化EGFP基因在Cos—7细胞表达，且对细胞无毒副作用。结论：自制白蛋白微泡是一种安全、有效的新型基因载体，在一定超声条件控制下，能增强基因的转导与表达，有良好的靶向性，提示该技术有应用于临床基因治疗的广阔前景。     

原代骨髓基质细胞层对逆转录病毒载体介导的造血干/祖细胞基因转导的支持效应

为探讨建立原代骨髓基质细胞层的方法并观察基质接触对造血干／祖细胞(HSC／HPC)基因转移的影响，采用Ficoll—Hypaque分离成人骨髓单个核细胞(MNC)，用基质细胞培养液培养，传代4次以建立原代骨髓基质细胞层。将经细胞因子预刺激的造血干／祖细胞接种到经辐照处理的基质细胞层上，进行逆转录病毒介导的多药耐药基因(mdr1)转导，以半固体集落培养和聚合酶锭反应法(PCR)检测长春新碱(VCR)抗性集落数和mdr1基因扩增片段以测定转导效率。结果表明：原代骨髓基质细胞培养传代4—6周形成混合贴壁细胞层，主要由成纤维细胞组成。集落法和PCR法检测显示基质接触能提高骨髓造血干／祖细胞基因转导效率2.1—3.3倍，对逆转录病毒介导的造血干／祖细胞基因转导具有明显的支持效应。结论：基质细胞接触联合细胞因子作用可提高逆转录病毒介导的造血干／祖细胞基因转导效率。     

小发夹RNA对白血病K562细胞血管内皮生长因子受体Fit-1基因表达的抑制作用

本研究观察小发夹RNA对白血病细胞血管内皮生长N子受体flt-1基因表达的抑制作用并探讨其对白血病细胞侵袭能力的影响及作用机制。采用脂质体介导的方法将构建的人flt-1基N特异性shRNA真核表达载体转染入K562细胞,用（3418抗性筛选获得阳性克隆;抽提基因组DNA,用PCR方法验证shRNA基因对K562细胞的转染;以RT—PCR和免疫印迹反应检测flt-1mRNA和蛋白表达量的变化;用Boyden小室体外侵袭实验检测白血病细胞的侵袭能力;RT～PCR方法检测白血病细胞MMP-2和MMP-9的表达。结果表明,flt-1基因特异性shRNA真核表达载体转染入白血病细胞株K562,G418筛选2周获得阳性克隆;PCR检测证实shRNA基因整合入白血病细胞基因DNA;携有shRNA的flt-1基因能明显下调白血病细胞内flt-1基因mRNA表达水平;设计的2种不同flt-1shRNA序列能不同程度干扰flt—1基因和蛋白在细胞中的表达,两纽阳性细胞中flt-1基因表达抑制率分别为46．1％和65．4％;flt—1 shRNA转染白血病细胞系K562细胞后,MMP-2和MMP-9mRNA表达水平均较转染前明显下降;阳性细胞穿透人工重组基底膜的能力（4．3±1．2）％较对照组（12．7±1．9）％及（9．6±1．7）％明显降低（P〈0．01）。结论：VEGF受体flt-1特异性shRNA的真核表达载体能够高效转染入白血病细胞株K562,有效抑制flt-1基因的表达,并使白血病细胞体外侵袭能力减弱,MMP-2和MMP-9mRNA表达水平下降。这提示VEGF可能通过与其受体结合调控MMP-2和MMP-9的方式,参与白血病细胞的转移。     

醛脱氢酶基因转导介导的K562细胞对环磷酰胺的耐受性

本研究的目的是观察经醛脱氢酶基因（ALDH1）转导的造血细胞对环磷酰胺的耐受性，以逆转录病毒载体pLXSN-ALDH1将醛脱氢酶基因是导入人造血细胞系K562，应用PCR证实原病毒的整合，用RT－PCR检测ALDH1基因表达和MTT法分析ALDH1过表达导致的4－氢过氧环磷酰胺的耐药表型。结果发现，逆转录病毒成功地介导了醛脱氢酶基因转移，全长ALDH1cDNA以原病毒形式整合入受体K562细胞基因组，RT－PCR检测到ALDH1基因转录表达。ALDH1过表达的基因转移细胞对环磷酰胺的耐受性明显提高（4倍），IC50≈10μmol／L。结论提示，体外ALDH1过表达足以引起对环磷酰胺耐受，为体内ALDH1基因转移以保护骨髓细胞免受环磷酰胺的毒性作用提供了实验依据。     

增强型绿色荧光蛋白转染猪骨髓间充质干细胞特性观察

目的：借助质粒将增强型绿色荧光蛋白（EGFP）基因转染猪骨髓干细胞（MSC）,观察转染后EGPP在（MSC）内表达情况及MSC生长特性。方法：1月龄小型香猪为MSC供体,EGFP基因转染MSC,计算转染效率,流式细胞仪鉴定G418筛选后EGFP基因稳定表达率和转染后细胞增殖周期改变。结果：转染率为（36．9±3．4）％;G418筛选后EGFP表达率75．6％,EGFP转染MSCG0／G1期MSC比例较对照组明显增加（P〈0．01）,S＋G2／M期MSC比例减少（P〈0．01）。结论：猪MSC经基因转染和G418筛选,获得EGFP稳定表达;转染和G418筛选后MSC增殖能力降低,G0／G1期MSC比例增加,S＋G2／M期MSC比例下降。     

特异性RNA干扰阻抑骨髓基质细胞SDF-1表达对Jurkat细胞黏附及药物敏感性的影响

目的观察特异性RNA干扰(RNA i)阻抑急性白血病骨髓基质细胞衍生因子-1(SDF-1)表达对共培养的急性白血病细胞系Jurkat细胞黏附及药物敏感性的影响。方法脂质体介导SDF-1特异性RNA i质粒转染培养的急性白血病患者骨髓基质细胞,G418筛选阳性混合克隆,ELISA法检测SDF-1表达;Jurkat细胞与之共培养,通过细胞计数计算黏附率,MTT法检测对阿霉素的药物敏感性。以未转染急性白血病骨髓基质细胞及正常骨髓基质细胞作为对照。结果转染阳性克隆组、未转染急性白血病组及正常对照组骨髓基质细胞培养上清SDF-1水平分别为每周(1920±205)pg/105细胞、(12 370±1355)pg/105细胞和(6620±770)pg/105细胞;与之共培养的Jurkat细胞黏附率分别为(28.8±2.6)%,(57.4±3.8)%和(45.2±4.0)%,阿霉素50%抑制浓度分别为585,6162,1758 nmol/L。结论RNA i阻抑SDF-1表达的骨髓基质细胞使Jurkat细胞黏附减少,对阿霉素的敏感性增加。     

大鼠转化生长因子β1基因转染成骨细胞后的表达

背景将生物材料复合细胞因子基因,或复合转入细胞因子基因的细胞植入骨缺损处可以促进骨修复.目的观察将大鼠转化生长因子β1基因转染成骨细胞后进行骨缺损基因治疗的可行性.设计对照观察实验.单位华中科技大学同济医学院附属协和医院骨科.对象新生SD大鼠5只,雌雄不限.方法实验于2000-02/09在华中科技大学同济医学院附属协和医院骨科实验室完成.通过脂质体介导将转化生长因子β1基因导入大鼠成骨细胞,并以质粒pcDNA3转染细胞作为对照.转染24 h后通过链霉亲和素-生物素化过氧化物酶复合物法和原位杂交法检测目的基因瞬时表达的情况.采用G418筛选转染细胞2周,获得阳性细胞克隆,用链霉亲和素-生物素化过氧化物酶复合物法检测转染细胞稳定表达转化生长因子β1的情况.主要观察指标链霉亲和素-生物素化过氧化物酶复合物法和原位杂交法检测转染细胞基因表达情况.结果①pcDNA3-TGF-β1转染成骨细胞瞬时表达组化检测和原位杂交检测结果24 h转染成骨细胞胞浆中充满染色的棕黄色颗粒,对照组空载体转染细胞胞浆中则没有棕黄色颗粒,说明转基因细胞中转化生长因子β1 mRNA明显增高.②G418筛选转基因细胞组化检测G418筛选2周后的转染细胞仍然有较高的转化生长因子β1表达.结论利用基因转染技术可使成骨细胞瞬时、高效表达细胞因子,转染后瞬时和筛选2周后,均呈现转化生长因子β1基因转染成骨细胞后稳定的高表达,说明采用细胞因子基因转染成骨细胞进行骨缺损的基因治疗具有可行性.     

Toward gene therapy for Gaucher disease

We are studying the transfer and expression by retroviral vectors of the human glucocerebrosidase (GC) gene into bone marrow cells as a model of gene therapy for genetic diseases of hematopoietic cells. A simple retroviral vector (G2) was developed that contains a normal human GC cDNA under the control of the Moloney murine leukemia virus long-terminal repeat (LTR) enhancer/promoter. Murine bone marrow was transduced with the G2 vector and maintained in long-term bone marrow culture (LTBMC). Expression of the human GC gene in the transduced murine LTBMC cells exceeded the level of endogenous murine GC mRNA. Murine bone marrow cells were also transduced with G2 and transplanted into irradiated syngeneic recipients. High levels of GC gene transfer and expression were seen in day-12 CFU-S foci, and to a lesser extent in the hematopoietic organs 4 months after gene transfer/bone marrow transplant (BMT). Human bone marrow, from a patient with Gaucher disease, was also used in studies of GC gene transduction. Gene transfer into 35-40% of the Gaucher hematopoietic progenitor cells was achieved, following prestimulation of the marrow with recombinant hematopoietic growth factors. Equal rates of gene transfer were obtained using either total marrow mononuclear cells or progenitor cells enriched 100-fold by immunomagnetic bead separation. GC gene transduction corrected the enzymatic deficiency of the Gaucher marrow. Our results demonstrate the potential utility of retroviral vector-mediated gene transfer for gene therapy of Gaucher disease. Current efforts are aimed at achieving more consistent in vivo GC expression in the murine BMT model and demonstrating transduction of pluripotent human hematopoietic stem cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Human cord blood cells as targets for gene transfer: potential use in genetic therapies of severe combined immunodeficiency disease

Human cord blood (CB) contains large numbers of both committed and primitive hematopoietic progenitor cells and has been shown to have the capacity to reconstitute the lympho-hematopoietic system in transplant protocols. To investigate the potential usefulness of CB stem and progenitor cell populations to deliver new genetic material into the blood and immune systems, we have transduced these cells using retroviral technology and compared the efficiency of gene transfer into CB cells with normal adult human bone marrow cells using a variety of infection protocols. Using two retroviral vectors which differ significantly in both recombinant viral titers and vector design, low density CB or adult bone marrow (ABM) cells were infected, and committed progenitor and more primitive hematopoietic cells were analyzed for gene expression by G418 drug resistance (G418r) of neophosphotransferase and protein analysis for murine adenosine deaminase (mADA). Standard methylcellulose progenitor assays were used to quantitate transduction efficiency of committed progenitor cells, and the long term culture-initiating cell (LTC-IC) assay was used to quantitate transduction efficiency of more primitive cells. Our results indicate that CB cells were more efficiently transduced via retroviral- mediated gene transfer as compared with ABM-derived cells. In addition, stable expression of the introduced gene sequences, including the ADA cDNA, was demonstrated in the progeny of infected LTC-ICs after 5 wk in long-term marrow cultures. Expression of the introduced ADA cDNA was higher than the endogenous human ADA gene in the LTC-IC-derived colonies examined. These studies demonstrate that CB progenitor and stem cells can be efficiently infected using retroviral vectors and suggest that CB cells may provide a suitable target population in gene transfer protocols for some genetic diseases.     

Preincubation with endothelial cell monolayers increases gene transfer efficiency into human bone marrow CD34(+)CD38(-) progenitor cells

Retroviral gene transfer studies targeting bone marrow CD34(+)CD38(-) stem cells have been disappointing because of the rarity of these cells, their G(0) cell cycle status, and their low or absent expression of surface retroviral receptors. In this study, we examined whether preincubation of bone marrow CD34(+)CD38(-) stem cells with a hematopoietically supportive porcine microvascular endothelial cell line (PMVECs) could impact the cell cycle status and expression of retroviral receptors in pluripotent CD34+CD38- cells and the efficiency of gene transfer into these primitive target cells. PMVEC coculture supplemented with GM-CSF + IL-3 + IL-6 + SCF + Flt-3 ligand induced >93% of the CD34(+)CD38(-) population to enter the G(1) or G(2)/S/M phase while increasing this population from 1.4% on day 0 to 6.5% of the total population by day 5. Liquid cultures supplemented with the identical cytokines induced 73% of the CD34(+)CD38(-) population into cell cycle but did not maintain cells with the CD34(+)CD38(-) phenotype over time. We found no significant increase in the levels of AmphoR or GaLVR mRNA in PMVEC-expanded CD34(+)CD38(-) cells after coculture. Despite this, the efficiency of gene transfer using either amphotropic vector (PA317) or GaLV vector (PG13) was significantly greater in PMVEC-expanded CD34(+)CD38(-) cells (11.4 +/- 5.6 and 10.9 +/- 5.2%, respectively) than in either steady state bone marrow CD34(+)CD38(-) cells (0.6 +/- 1.7 and 0.2 +/- 0.6%, respectively; p < 0.01 and p < 0.01) or liquid culture-expanded CD34(+)CD38(-) cells (1.4 +/- 3.5 and 0.0%, respectively; p < 0.01 and p < 0.01). Since PMVEC coculture induces a high level of cell cycling in human bone marrow CD34(+)CD38(-) cells and expands hematopoietic cells capable of in vivo repopulation, this system offers potential advantages for application in clinical gene therapy protocols.     

RNA干扰骨髓基质细胞衍生因子表达对共培养Jurkat细胞增殖及凋亡的影响

目的探讨阻抑骨髓基质细胞衍生因子(SDF1)表达对与其共培养的Jurkat细胞增殖、凋亡的影响。方法脂质体介导SDF1特异性RNA干扰质粒转染培养的急性白血病骨髓基质细胞,G418筛选阳性克隆(A组),采用ELISA法检测SDF1表达变化;与Jurkat细胞共培养,绘制生长曲线并计算倍增时间,用流式细胞术检测细胞周期,末端脱氧核苷酸转移酶介导的dUTP缺失末端标记(TUNEL)法检测细胞凋亡,免疫细胞化学检测增殖细胞核抗原(PCNA)、Bcl2、Bax、Fas、FasL表达。以未转染急性白血病骨髓基质细胞(B组)及正常骨髓基质细胞(C组)作为对照。结果A组骨髓基质细胞培养上清SDF1含量为(384±41)pg/ml,较B组[(2474±271)pg/ml]、C组[(1324±154)pg/ml]明显降低。与之共培养的Jurkat细胞,A组与B组、C组比较,细胞增殖速度减缓,倍增时间延长(A组42h,B组29h,C组33h);细胞周期分析G0/G1期细胞比例增多[A组(28.47±2.39)%,B组(19.43±2.80)%,C组(27.15±2.07)%],S期细胞减少[A组(25.57±1.90)%,B组(74.48±3.23)%,C组(60.99±2.33)%],G2/M期细胞增多[A组(45.96±3.24)%,B组(6.09±1.96)%,C组(11.86±1.98)%];细胞凋亡率增加[A组(15.2±0.8)%,B组(5.4±0.7)%,C组(9.5±0.4)%];PCNA、Bcl2、Fas表达减少,Bax、FasL表达增多。结论阻抑SDF1表达在一定程度上抑制与骨髓基质细胞共培养的Jurkat细胞的增殖活性,并促进其凋亡。     

Comparison of the effects of growth factors on retroviral vector-mediated gene transfer and the proliferative status of human hematopoietic progenitor cells

We have examined the ability of the recombinant hematopoietic growth factors (HGF) interleukin-3 (IL-3), IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) to increase retroviral vector-mediated gene transfer into human hematopoietic progenitor cells (HPC). The efficiency of neo gene transfer by the N2 vector into human HPC was enhanced by preculture with either GM-CSF or IL-3 (but not IL-6) and with each combination of the three factors. The combination of IL-3 plus IL-6 consistently produced significantly higher levels of G418-resistant colonies (50-60%) than any of the other combinations of HGF tested. Following preculture with HGF and transduction by N2, marrow was maintained in long-term bone marrow culture (LTBMC) for 2 months. The levels of G418-resistant HPC remained stable, and no apparent depletion of total HPC content resulted from the prior exposure to highly stimulatory doses of factors. The proliferative status of the HPC, following exposure to the HGF, was measured as the percentage of HPC that were inhibited from forming colonies by exposure to the S-phase-specific drug, hydroxyurea. The ability of the different HGF to increase the rate of gene transfer by N2 correlated significantly with the extent to which they stimulated HPC proliferation. These results suggest that the mechanism by which HGF increase rates of gene transfer into HPC is by stimulating cell proliferation. Techniques that produce high rates of gene transfer into long-lived human HPC will facilitate studies to quantitate expression of exogenous genes in hematopoietic cells and may be applicable to clinical gene therapy.     

逆转录病毒介导的GM-CSF在骨髓基质细胞中基因转移与表达

为了探索逆转录病毒介导的GM-CSF在骨髓基质细胞(BMSC)中的基因转移与表达,采用电穿孔法将重组质粒pLXSN/GM和空载体pLXSN转染PA317细胞,经G418筛选,用抗性克隆培养上清液成功地感染了BMSC。经PCR和Southern blot分析证实BMSC基因组中整合有外源NeoR和GM-CSF cDNA,原位杂交显示有较强的GM-CSFmRNA的表达,经增殖法和集落形成法表明转染的BMSC分泌较多的GM-CSF。据此表明,转染的BMSC较未转染BMSC具有更强的支持造血功能,提示BMSC可作为造血功能障碍基因治疗的靶细胞,为GM-CSF基因治疗血液病奠定基础。