腺相关病毒载体介导外源基因导入人外周血干细胞的研究

目的：观察腺相关病毒载体介导外源基因导入人外周血干细胞的转染效率及表达。方法：本文采用腺相关病毒（adeno-associated virus,AAV）载体介导的基因转移方法，将绿色荧光蛋白（green fluorescent protein,GFP）基因和人多药耐药基因（multi-drug resitance,MDR1）导入人外周造血干／祖细胞，并对转染效率和转基因造血细胞的耐药性进行了初步研究。结果：rAAV/GFP感染CD34阳性细胞后，在荧光显微镜下观察，约30％细胞中可见绿色荧光。将rAAV/MDR1重组病毒感染CD34阳性细胞，经PCR和MTT法证实，导入MDR1基因的CD34阳性细胞对秋水仙素的耐药性与未导入MDR1基因的细胞有明显差异。结论：腺相关病毒载体能有效地将外源基因导入外周血CD34阳性细胞，并可在其中有效地表达。     

5氮2′脱氧胞苷对人卵巢癌细胞凋亡及DNA错配修复基因表达的影响

目的:探讨胎肝AFT024细胞对人类脐血造血干细胞体外扩增的作用及对多药耐药基因(MDR1)转染效率的影响。方法:应用AFT024细胞支持下体外长期培养的方法将人类MDR1基因转入脐血CD34 细胞,观察细胞扩增倍数来检测AFT024细胞对造血干/祖细胞的扩增能力,采用RT-PCR、流式细胞术及耐药集落检测的方法测定基因转染效率、P-糖蛋白(P-gp)的表达及其功能活性。结果:(1)培养21d后AFT024细胞对有核细胞总数(TNC)的扩增没有明显作用,但CD34 细胞和集落形成细胞(CFC)的扩增倍数[(37.9±13.9)倍和(27.1±13.3)倍]均明显高于对照组[(9.1±2.3)倍和(7.7±3.6)倍],差异均有统计学意义(P<0.01)。(2)RT-PCR法可在AFT024组的转染细胞中检测到较高的MDR1mRNA水平,AFT024组基因转染效率(46.0%)明显高于对照组(15.2%);两组P-gp的表达分别为(31.7±10.2)%和(12.6±3.9)%;Rhodamine-123排出试验显示,具有P-gp功能活性的细胞分别为(35.5±11.4)%和(16.6±3.2)%,组间比较差异均有统计学意义(P<0.01)。结论:AFT024细胞具有较强的扩增造血干/祖细胞的能力,并能明显提高MDR1基因在脐血CD34 细胞中的转染效率。     

多药耐药基因在白血病细胞的高效转移与表达研究

目的　研究逆转录病毒介导多药耐药基因 MDR1的转移与表达。方法　用 MDR病毒转导人类白血病细胞K5 6 2和 NB4,获得耐药细胞系 ;外源性 MDR1基因的转移和表达用聚合酶链反应 (PCR)、流式细胞术 (FCM)和半固体集落培养法分析。结果　 MDR病毒转导使白血病细胞获得经典多药耐药表型 ,78.0 %～ 98.7%的细胞表达 P-糖蛋白 ;PCR分析证实耐药细胞整合有 MDR原病毒 ,并共表达全长和异常剪切 MDR1转录本。以 K5 6 2细胞为模型 ,FCM和集落培养法发现共培养法的基因转导率 (6 7.9%～72 .5 % )明显高于上清法 (33.1%～ 46 .8% ) ,加入生长因子可提高基因转导率约 2 3%。结论　逆转录病毒可介导MDR1基因在髓系白血病细胞进行有效的转移与表达 ;MDR1基因可作为选择性标志用于基因治疗     

人多药耐药基因mdr1野生型mRNA转导脐血干细胞提高其对化疗耐药性的体外研究

目的：将人类多药耐药基因(mdr1)全长野生型mRNA转导至人脐带血干细胞，分析其P糖蛋白的表达及干细胞的耐药性。方法：通过体外转录方法经人野生型mdr1基因全长cDNA制备相应的mRNA，经脂质体介导转染人造血干细胞，采用RT—PCR和Western blot检测转染效果，流式细胞仪检测蛋白表达、体外培养及细胞活率计数观察耐药性。结果：转染后P糖蛋白表达丰度为9．05％，对照组为1．01％；转染后具有Rhodamin-123排泌功能的细胞占98．72％，对照组为66．83％；转染后细胞耐药性明显增强，P=0．002。结论：通过脂质体介导，将人类mdr1基因野生型全长mRNA转导入脐血干细胞，增加了P糖蛋白的表达，提高了细胞的耐药性。该系细胞可用于缓解和治疗恶性肿瘤化疗带来的骨髓抑制。     

体外转录法制备人野生型MDR1基因mRNA

目的应用体外转录法大量制备人野生型多药耐药基因MDR1的mRNA,转染人造血干细胞后检测P糖蛋白表达.方法含人野生型MDR1基因的cDNA经酶切连接后构建可体外转录的模板,经体外转录得到mRNA,转染人造血干细胞,通过RT-PCR法检测mRNA及Western-bloting法检测P糖蛋白表达.结果转染后细胞mRNA相对含量(1.380)明显高于对照组(1.105)(P＜0.01);Western-bloting可见转染组MDR1基因编码的P-gp蛋白条带明显强于对照组.结论经体外转录法可大量制备人野生型MDR1基因的mRNA,并可成功应用于转染人造血干细胞,产生P糖蛋白表达.     

PA317产生高滴度带有人TNF-α基因逆转录病毒的研究

逆转录病毒介导的基因转移技术要过渡到临床应用，主要解决如何使病毒载体具有高滴度而不具有复制活性．本文旨在探索建立一种合适的方法，能产生高滴度而且是安全的逆转录病毒载体。采用带有人肿瘤坏死因子基因的LXSN载体转染PA317包装细胞，建立产病毒的包装细胞株，结果表明：病毒载体滴度受包装培养液体积和胎牛血清浓度影响：包装细胞在32℃产生的病毒滴度比37℃高，而且比较稳定。产病毒包装细胞和被感染的靶细胞经PCR分析显示．被转染和被转导的细胞都有病毒基因的整合．而且包装细胞不会产生具有复制活性的逆转录病毒，因此能进一步用于临床研究．     

iNOS基因转染人CD3AK细胞的实验研究

目的　构建一氧化氮供体CD3AK/iNOS细胞。方法　用PCR技术从 pCMV/iNOS质粒中扩增出iNOS全长cDNA ,与逆转录病毒pLNCX构建重组质粒 pLNCX/iNOS ;通过脂质体介导把重组质粒转染入包装细胞PA3 17中 ,经G418筛选出抗性克隆。通过NIH3T3细胞测定病毒滴度。用病毒上清感染人CD3AK细胞。测定CD3AK/iNOS细胞培养上清中NO含量及iNOS活性。结果　经过酶切分析和核苷酸序列分析鉴定重组质粒的正确性。G418筛选出 16个抗性克隆 ,能稳定合成并分泌重组逆转录病毒颗粒。NIH3T3细胞测定病毒滴度为 2 .1× 10 4CFU /ml。经重组逆转录病毒上清转染后CD3AK /iNOS细胞合成并分泌的NO含量及iNOS活性比CD3AK细胞明显增高。结论　逆转录病毒载体 pLNCX可有效地介导iNOS的转染。成功构建CD3AK/iNOS细胞 ,有效提高iNOS活性及NO含量。     

CD基因联合 5-Fc治疗人胃癌的实验研究

目的：通过 转基因方法观察自杀基因CD对人胃癌细胞株7901的体内外 杀伤作用,并观察组织病理变化。方法：应用逆转录病毒方法转导自杀基因CD,通过体外实验观察CD 基因对人胃癌7901细胞的杀伤性和旁观者效应;体内实验中首先在BALB／cnu/nu裸鼠建立胃癌模型,然后将病毒上清注入瘤体内,并结合应用前药,观察肿上瘤体积变化,通过病理切片观察组织病理变化。结果：CD基因在外外即显出明显的杀伤作用（含旁观者效应）,20％的转基因细胞可以杀伤70％－80％的肿瘤细胞。在实验动物体内,CD基因结合前药5－Fc可显著杀伤肿瘤,而单纯转导CD基因和只用5－Fc并不能起到杀伤作用。结论：自杀基因CD联合前药5－Fc对胃癌产生显著杀伤作用,不仅转基因细胞被杀死,而且通过旁观者效应杀伤大量周围细胞。CD／5－Fe在体内试验对胃癌有显著杀伤作用。     

二氢叶酸还原酶耐药基因对人外周血CD34+细胞的保护作用

目的 探讨突变的二氢叶酸还原酶（ｍＤＨＦＲ）耐药基因在人外周血ＣＤ３４＾＋细胞中抗甲氨喋呤（ＭＴＸ）的效应。方法 应用免疫磁珠分选系统（ＭＡＣＳ）分离纯化外周血ＣＤ３４＾＋细胞后,用含ｍＤ－ＨＦＲ基因的逆转录病毒上清转染人外周血ＣＤ３４＾＋细胞,采用造血祖细胞集落形成实验进行转导后细胞抗ＭＴＸ分析。结果 在ＭＴＸ（２０ｎｍｏｌ／Ｌ）存在的条件下,转导ｍＤＨＦＲ耐药基因的外周血ＣＤ３４＾＋细胞集落形     

逆转录病毒介导高效的白血病细胞基因转移

目的建立安全高效的逆转录病毒介导的基因转移系统,为白血病基因治疗提供实验基础。方法分别用脂质体转染和小鼠逆转录病毒转导方法,将含标志基因ＮｅｏＲ的逆转录病毒载体ｐＬＸＳＮ导入双嗜型包装细胞ＧＰ＋ｅｎｖＡｍ１２,获得重组逆转录病毒;用含病毒上清感染白血病细胞系（ＮＢ４、Ｕ９３７和ＴＨＰ－１）,并分析对Ｋ５６２细胞的转导效率。结果脂质体ＤＯＳＰＥＲ转染法获得病毒滴度为８．０×１０５ＣＦＵ／ｍｌ,而病毒感染法高达１．６×１０７ＣＦＵ／ｍｌ。经Ｇ４１８选择,ＰＣＲ证实ＮｅｏＲ基因被整合到白血病细胞基因组中,巢式ＰＣＲ与补救分析均未检测到辅助病毒存在。单个集落Ｋ５６２细胞的ＰＣＲ分析证实,基因转移效率可达９３．３％～１００％。结论逆转录病毒介导的基因转移系统是高效、安全的,有助于人类白血病的基因治疗研究。     

In vitro study on the cloning and transduction of human O6-methylguanine-DNA-methyltransferase cDNA into human umbilical cord blood CD34+ cells

Objective: To explore whether human umbilical cord blood hematopoietic progenitor cells transduced with human O6-methylguanine-DNA-methyltransferase (MGMT) gene could increase resistance to 1,3-Bis(2-Chloroethyl)-1-Nitrosourea (BCNU). Methods: The cDNA encoding the MGMT was isolated by using RT-PCR method from total RNA of fresh human liver, the fragment was cloned into pGEM-T vector and further subcloned into G1Na retrovirus vector. Then the G1Na-MGMT was transduced into the packaging cell lines GP+E86 and PA317 by LipofectAMINE. By using the medium containing BCNU for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, high titer amphotropic PA317 producer clone with the highest titer up to 5.8′ 105 CFU/ml was obtained. Cord blood CD34+ cells were transfected repeatedly with supernatant of retrovirus containing human MGMT-cDNA under stimulation of hemopoietic growth factors. Results: The retrovirus vector construction was verified by restriction endonuclease analysis and DNA sequencing. PCR, RT-PCR, Southern Blot, Western Blot and MTT analyses showed that MGMT drug resistance gene has been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently. The transgene cord blood CD34+ cells conferred 4-folds stronger resistance to BCNU than untransduced cells. Conclusion: The retrovirus vector-mediated transfer of MGMT drug resistance gene into human cord blood CD34+ cells and its expression provided an experimental foundation for gene therapy in clinical trial.     

IN VITRO STUDY ON THE CLONING AND TRANSDUCTION OF HUMAN O~6-METHYLGUANINE-DNA-METHYLTRANS cDNA INTO HUMAN UMBILICAL CORD BLOOD CD34~ CELLS

Myelosuppressionisoftenadose-limitingsideeffectofchemotheropeaticdrugsinthetreatmentofcancer.Transducingresistancegenesintohematopoieticprecursorsthatconferprotectionagainstthehematotoxicityofanticanceragentshasbeenprovedtoreducemyelosuppression.Inthisregard,effortshavebeenmadetopotentiatetheresistanceconferredbythismethod.Chemotheraopeaticdrugssuchasalkylatingagents(temozolomide,BCNU,mitozolomide,chlorozotocinandrocarbazine)arecytotoxicasaconsequenceofformingO'-alkylguanineDNAadducts.O6me…     

Improvement of combination chemotherapy tolerance by introduction of polycistronic retroviral vector drug resistance genes MGMT and MDR1 into human umbilical cord blood CD34+ cells.

We obtained a full-length cDNA fragment encoding human O(6)-methylguanine-DNA-methyltransferase (MGMT) from the liver tissue of a patient with cholelithiasis by RT-PCR and confirmed by DNA sequencing. The polycistronic retrovirus vector G1Na-MGMT-Neo(r)-IRES-MDR1 was constructed and verified by restriction endonuclease analysis and DNA sequencing. The vector was transfected into packaging cells GP+E86 and PA317 by the LipofectAMINE method. Cord blood CD34+ cells were transfected with the supernatant of retrovirus containing human MGMT and MDR1cDNA under stimulation of hematopoietic growth factors. PCR, RT-PCR, Southern Blot, Western Blot, FACS and MTT analyses showed that dual drug resistance genes have been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently. The transgene cord blood CD34+ cells conferred 5.8-6.3-fold stronger resistance to P-glycoprotein effluxed drugs and 5-fold to BCNU than untransduced cells. The polycistronic retrovirus vector mediated transfer of two different types of drug resistance genes into human cord blood CD34+ cells and co-expression provided an experimental foundation for improving combination chemotherapy tolerance in clinical practice.     

Efficient detection and selection of immature rhesus monkey and human CD34+ hematopoietic cells expressing the enhanced green fluorescent protein (EGFP).

The feasibility of using the enhanced green fluorescent protein (EGFP) as a selectable reporter molecule of retroviral-mediated gene transfer in immature rhesus monkey and human CD34+ hematopoietic cells was examined. Retroviral transduction with the MFG-EGFP retroviral vector resulted in readily detectable EGFP expression in 27% of human and 11-35% of rhesus monkey bone marrow cells, and in 17-38% of rhesus monkey peripheral blood cells mobilized with FLT3 ligand (FL) and granulocyte colony-stimulating factor (G-CSF). In addition, we used the human CD34+ KG1A cell line as a model to study viability and growth of successfully transduced cells. Cultures of mock- and EGFP-transduced KG1A cells generated equal viable cell numbers for at least 1 month, indicating the absence of a cytotoxic effect of EGFP expression in these cells. FACS selection on the basis of EGFP and CD34 expression resulted in enriched subsets (> or = 87%) of CD34+ EGFP-negative and CD34+ EGFP-positive KG1A, rhesus monkey and human bone marrow cells, demonstrating the potential of obtaining almost pure populations of transduced immature hematopoietic cells. EGFP expression was also readily demonstrated in erythroid and granulocyte/macrophage colonies derived from the CD34+ EGFP-positive rhesus monkey and human bone marrow cells by either inverted fluorescence microscopy or flow cytometry. Using four-color flow cytometry, EGFP expression could also be demonstrated in viable and phenotypically defined immature subpopulations of the CD34+ cells, ie those expressing little or no HLA-DR (rhesus monkey) or CD38 (human) antigens at the cell surface. These results demonstrate that EGFP is a very useful marker to monitor gene transfer efficiency in phenotypically defined immature rhesus monkey and human hematopoietic cell types and to select for these cells by multicolor flow cytometry prior to transplantation.     

切割MDR1 RNA的核酶(Ribozyme)对肝癌多药耐药细胞株BEL-7402/DOX化疗耐药性的逆转作用

为逆转肿瘤多药耐药基因(MDR1)产物P-gp蛋白所介导的肿瘤细胞对多种化疗药物的耐受性,设计合成了一种能切割MDR1 mRNA第196密码子GUC序列的锤头状核酶(Ribozlyme)并定向克隆于转录病毒载体pDOR-neo的BamH Ⅰ位点.经病毒包装细胞PA317包装后感染人肝癌多药耐药细胞株BEL-7402/DOX细胞,经G418筛选得到稳定的转化细胞株.Northem Blot杂交证实包装细胞PA317及转化的BEL-7402/DOX细胞中均有病毒的高表达,RT-PCR证实转化细胞中MDR1 mRNA与未转化细胞相比明显减少甚至不能扩增出来,流式细胞技术检测转化细胞P-gp的表达与非转化细胞的93.4～97.5%相比下降至8.2～14.6%.MTT法检测证实转化细胞对多种化疗药物重新产生较高的敏感性.结果表明,表达Ribozyme的逆转录病毒载体转化肝癌多药耐药细胞BEL-7402/DOX后能有效抑制MDR1的表达和翻译,使已产生耐药的肿瘤细胞的多药耐药表型发生逆转.     

The FBMD-1 stroma cell line secretes a unique moiety which can increase retroviral transduction of lineage-committed and primitive human peripheral blood progenitor cells

Peripheral blood progenitor cells are a prime target for gene therapy approaches. As recent data point to the relevance of soluble stroma factors for the efficient transduction of progenitor cells, we tested the stroma-conditioned medium (SCM) of the two cell lines FBMD-1 and L88/5 as well as desulfated and O-sulfated heparin (HS dS and HS OS) for their effect on transduction of peripheral blood progenitor cells. We transduced CD34+ cells of nine tumor patients with the retroviral SF-MDR vector containing the human multidrug resistance 1 (MDR1) gene under serum-free conditions on the fibronectin fragment CH-296 with or without SCM. Provirus-specific polymerase chain reaction showed a median 1.6-fold higher integration rate of the transgene into committed progenitor cells for the group with added FBMD-1 SCM (P=.008). This was maintained after 2 (P=.02) and, as a trend, after 5 weeks of stroma-dependent long-term culture. We found a median 1.5-fold increase in rhodamine-123 (Rh-123) exclusion in myeloid lineage-committed progeny cells following transduction in the presence of FBMD-1 SCM (P=.0004). After 2 or 5 weeks of long-term culture, a significantly higher proportion of Rh-123(dull) cells could still be detected in the FBMD-1 SCM transduction group (P=.003 and P=.04, respectively). L88/5 SCM or HS OS or HS dS was not effective as supplement for improving gene transfer. The FBMD-1 stroma cell line appears to secrete a unique moiety, which can increase retroviral transduction of lineage-committed and primitive progenitor cells. The FBMD-1 stroma activity is not attributable to heparan sulfate.     

PRELIMINARY STUDY OF RETROVIRAL MEDIATED TRANSFER OF THE HUMAN mdr-1 GENE INTO MURINE AND HUMAN HEMATOPOIETIC STEM/PROGENITOR CELLS

ＰＲＥＬＩＭＩＮＡＲＹＳＴＵＤＹＯＦＲＥＴＲＯＶＩＲＡＬＭＥＤＩＡＴＥＤＴＲＡＮＳＦＥＲＯＦＴＨＥＨＵＭＡＮｍｄｒ１ＧＥＮＥＩＮＴＯＭＵＲＩＮＥＡＮＤＨＵＭＡＮＨＥＭＡＴＯＰＯＩＥＴＩＣＳＴＥＭ／ＰＲＯＧＥＮＩＴＯＲＣＥＬＬＳＦｅｎｇＫａｉ冯凯Ｐｅ...     

Enhancement of Adenovirus-Mediated Gene Transfer to Human Bone Marrow Cells

Adenovirus infection of CD34⁺ hematopoietic stem/progenitor cells is dependent on the multiplicity of infection (MOI), time of incubation, the volume in which the co-incubation occurs and the presence or absence of growth factors. Studies revealed that a brief co-incubation (1-8 hours), resulted in low levels of transgene expression, suggesting that adenovirus infection of CD34⁺ cells occurs slowly, and optimal transduction requires a 24 hour exposure to adenovirus. Infection by Ad/β-gal or Ad/p53 at a MOI of 500:1 provided a high transduction efficiency but inhibited hematopoietic function. However, treatment at a MOI of 50-100 resulted in efficient transduction (10.7-15.7% positive) without detectable toxicity. Secondary proof of adenovirus transgene expression was demonstrated by detection of mRNA for p53 in Ad/p53 infected stem cells. We conclude that a 24 hour exposure to recombinant adenovirus encoding p53 or β-gal, at a MOI of 50-100 is optimal for in vitro gene transfer to BM cells and has no significant effect on hematopoietic function. Adenovirus-mediated transduction of BM cells can also be modulated by growth factors (IL-3, GM-CSF and G-CSF) with improved gene delivery and maintenance of hematopoietic function. In summary, adenovirus vectors can be used to transiently transduce stem cells, and conditions have been defined to maximize expression and limit inhibitory effects on CD34⁺ cells. These data support continued investigation of this vector for local cytokine delivery and purging of stem cell products.