提高多药耐药基因导入人CD34^＋细胞转导效率的探讨

目的 探讨逆转录病毒介导的多药耐药基因导入人ＣＤ３４＾＋细胞的影响因素,以提高基因转导效率。方法 用流式细胞术（ＦＣＭ）检测不同组合细胞因子及人骨髓基质细胞＋细胞因子支持的基因转导效率;用造血祖细胞集落培养观察耐药性;用ＦＣＭ检测不同浓度柴杉醇素对基因转导细胞的作用。     

不同造血生长因子对脐血有核细胞体外扩增作用的实验研究

目的：探讨造血生长因子不同组合方式对脐血有核细胞的扩增作用以及脐血扩增后Ｔ淋巴细胞和ＨＬＡ－ＡＢ、ＤＲ阳性细胞变化情况。方法：在脐血有核细胞体外培养体系中分别加入不同组合的细胞因子，观察细胞数、ＣＤ３４＋细胞、ＣＦＵ－ＧＭ、Ｔ４（ＣＤ４＋ＣＤ８－ＣＤ３＋）细胞、Ｔ８（ＣＤ４－ＣＤ８＋ＣＤ３＋）细胞以及ＨＬＡ－ＡＢ、ＤＲ阳性细胞的变化。结果：脐血有核细胞在体外液体培养体系中，经重组人干细胞因子（ｒｈＳＣＦ）、白细胞介素（ＩＬ）－３、ＩＬ－６、粒细胞集落刺激因子（Ｇ－ＣＳＦ）、粒－巨噬细胞集落刺激因子（ＧＭ－ＣＳＦ）和红细胞生成素（Ｅｐｏ）的作用下扩增效果最佳。结论：脐血有核细胞在各种造血生长因子的协同作用下可以在体外扩增。脐血扩增后Ｔ４、Ｔ８细胞减少，可能会降低脐血移植急性ＧＶＨＤ发生，但ＨＬＡ－ＡＢ和ＨＬＡ－ＤＲ阳性细胞数急剧上升，增加了免疫排斥的可能性。     

造血生长因子对脐血CD34^＋细胞的体外扩增作用

为探讨造血生长因子不同组合方式对脐血ＣＤ３４＋细胞的扩增作用、扩增细胞性能改变及合理的扩增时机，利用吸附单克隆抗体——磁珠分离系统分选出９５％～９９％纯度的脐血ＣＤ３４＋细胞，在体外液体培养体系中，经重组人干细胞因子（ｒｈＳＣＦ）、白细胞介素（ＩＬ）３、ＩＬ－６、粒－巨噬细胞集落刺激因子、粒细胞集落刺激因子（Ｇ－ＣＳＦ）和红细胞生成素（Ｅｐｏ）的不同组合扩增１～３周。结果表明，脐血ＣＤ３４＋细胞具有良好的扩增效应，细胞总数、集落形成细胞（ＣＦＣｓ）和ＣＤ３４＋细胞可分别扩增５００．０±８２．５倍、９４．０±２８．６倍和２４．０±３．８倍；ＳＣＦ是扩增最重要的生长因子，ＳＣＦ＋ＩＬ－３＋ＩＬ－６＋Ｇ－ＣＳＦ＋Ｅｐｏ组合的扩增效率最高；ＣＦＣｓ和ＣＤ３４＋细胞在１～２周维持在较高水平，以后即快速衰减；此外，扩增也加速了细胞的分化，至第３周时９３％ＣＦＣｓ为ＣＦＵ－ＧＭ，极少部分形成ＢＦＵ－Ｅ和ＣＦＵ－ＧＥＭＭ。因此，合理组合生长因子，把握适宜扩增时机，将有助于扩增细胞在质和量上满足移植和基因治疗等的要求。     

CD3＋细胞分选及临床应用

ＣＤ３４＋是造血干细胞的免疫表型，采用某种方法选择ＣＤ３４＋细胞，选择后ＣＤ３４＋细胞浓集，其百分率有较大增高，并可以有效去除Ｔ细胞及某些恶性肿瘤细胞，选择ＣＤ３４＋细胞移植可以减少异基因移植后急性，重度移植物抗宿主病（ＧＶＨＤ），并可能减少自体移植后原发病复发。本文介绍了造血干细胞的免疫表型，生物学特性及ＣＤ３＋细胞分选方法、临床应用等方面的研究进展。     

骨髓增生异常综合征CD34^＋细胞对不同生长因子的反应性研究

目的：更准确地研究造血生长因子对骨髓增生异常综合征（ＭＤＳ）造血干、祖细胞的影响及临床治疗效果。方法：利用吸附单克隆抗体的免疫磁珠分离系统分离纯化ＭＤＳ患者ＣＤ３４＋细胞，在体外半固体培养体系中，研究ＭＤＳＣＤ３４＋细胞对粒－巨噬细胞集落刺激因子（ＧＭ－ＣＳＦ）、白细胞介素３（ＩＬ－３）、红细胞生成素（Ｅｐｏ）、干细胞因子（ＳＣＦ）单独及联合应用的反应。结果：ＭＤＳＣＤ３４＋细胞在增殖分化过程中存在一定程度缺陷，单独应用生长因子不能有效地改善其缺陷，ＳＣＦ与ＧＭ－ＣＳＦ、ＩＬ－３、Ｅｐｏ等生长因子的联合应用可提高一部分患者造血祖细胞的集落形成能力，但在ＭＤＳ高危组，部分患者在正常集落形成能力改善的同时，白血病细胞集落也有不同程度的增长。结论：治疗ＭＤＳ患者须合理地联合应用造血生长因子。     

脐血CD34^＋细胞体外扩增的研究

采用ＤｙｎａｌＭ－４５０ＣＤ＿（３４）免疫磁珠分离纯化脐血ＣＤ＿（３４）￣＋细胞，并探讨了不同细胞因子［干细胞因子（ＳＣＦ）、白细胞介素６（ＩＬ－６）、白细胞介素３（ＩＬ－３）及红细胞生成素（Ｅｐｏ）］组合对脐血ＣＤ＿（３４）￣＋细胞的体外培养和扩增作用。结果表明：①经ＤｙｎａｌＭ－４５０ＣＤ＿（３４）免疫磁珠分离的脐血ＣＤ＿（３４）￣＋细胞，其纯度达８５％～。９５％；②甲基纤维素培养体系中，在不同组合的细胞因子作用下，脐血ＣＤ＿（３４）￣＋细胞的集落产率明显不同，单用ＩＬ－６最低，ＳＣＦ、ＩＬ－６、ＩＬ－３及Ｅｐｏ联用产率最高；③在低氧液体培养体系中，ＩＬ－６和ＩＬ６＋Ｅｐｏ不能有效地扩增脐血ＣＤ＿（３４）￣＋细胞，而其它细胞因子组合均可产生明显的扩增作用；其中加Ｅｐｏ的组合扩增效果显著高于无Ｅｐｏ的相应组合。脐血ＣＤ＿（３４）￣＋细胞分离、纯化及其体外扩增的研究对于脐血造血细胞库的建立，脐血造血细胞移植和基因导入的研究均具有重要意义。     

人参皂甙对人骨髓造血干细胞的增殖作用

目的：探讨人参皂甙（ＣＳ）对人骨髓ＣＤ３４＾＋造血干细胞的增殖作用。方法：采用Ｄｙｎａｌ Ｍ４５０ ＣＥ３４＾＋免疫磁珠分离法阳性选择获取高纯度的人骨髓ＣＳ３４＾＋造血干细胞,应用多向细胞（ＣＦＵ－Ｍｉｘ）体外培养技术,观察ＣＤ３４＾＋造血干细胞对ＣＳ的敏感性。结果：１经Ｄｙｎａｌ Ｍ０４５０ＣＤ３４＾＋免疫磁珠分离获得骨３髓ＣＤ３４＾＋细胞占骨髓单个核细胞（ＭＮＣ）的０．５２－１．３０％,Ｃ３４     

HSV-tk/GCV自杀基因疗法及其影响树突状细胞功能的实验研究

目的 研究单纯疱疹病毒－胸苷激酶／更昔洛韦（ＨＳＶ－ｔｋ／ＧＣＶ）自杀基因系统的特性,探讨转ＨＳＶ－ｔｋ基因后,肿瘤细胞被更昔洛韦（Ｇａｎｃｉｃｌｏｖｉｒ,ＧＣＶ）杀伤时的凋亡现象及对树突状细胞功能的影响。方法 以逆转录病毒法将ＨＳＶ－ｔｋ基因转人乳腺癌细胞株ＭＣＦ－７中,以Ｓｏｕｔｈｅｒｎ ｂｌｏｔ法对肿瘤细胞基因组ＤＮＡ中ｔｋ基因的整合进行鉴定,以流式细胞仪及电镜观察ＧＣＶ杀伤ＭＣＦ－７／ｔｋ细胞时的凋亡现象,由脐血ＣＤ３４＾＋细胞诱生树突状细胞,以＾３Ｈ－ＴｄＲ掺入法检测树突状细胞刺激同种异体Ｔ淋巴细胞增殖的能力。结果 以逆转录病毒法成功地将ＨＳＶ－ｔｋ基因转入ＭＣＦ－７细胞中,转染ｔｋ基因的ＭＣＦ－７细胞能被ＧＣＶ有效杀伤并存在凋亡现象,凋亡率可达３１．３％;由脐血ＣＤ３４＾＋细胞在ＧＭ－ＣＳＦ、ＴＮＦ     

骨髓基质细胞对人造血CD_34~+细胞体外扩增及基因转导的作用

目的：探讨造血基质细胞对人外周血干细胞体外培养扩增及基因转导的促进作用。方法：应用基质细胞支持培养扩增体系进行人造血干细胞体外培养扩增及基因转导。结果：骨髓基质细胞和造血生长因子共同支持组的造血ＣＤ＋３４细胞在体外培养３周后,其造血祖克隆形成能力较单纯造血生长因子支持组高３０．７％（Ｐ＜０．０５）。在有基质细胞支持时,逆转录病毒载体上清转导人造血ＣＤ＋３４细胞后,其造血细胞克隆中Ｎｅｏ基因阳性克隆是无基质支持对照组的２倍。结论：基质细胞的支持有维持造血干细胞原始造血活性及促进基因转导的双重好处。     

人脐血造血干／祖细胞移植的研究进展

人脐血作为一种可替代骨髓的造血干细胞资源，具有移植成活率高，移植物抗宿主反应轻的特点。脐血富含ＣＤ３４＋细胞，对异抗原刺激反应较低，具有高增生和长期骨髓重建的能力。脐血造血干细胞较外周血和骨髓更为原始，大部分ＣＤ３４＋细胞属于寝髓系分化细胞，ＣＤ３４＋ＣＤ３８－具有Ｂ－细胞和粒细胞两种分化途径的能力。脐血具有独特的免疫特性，能耐受异基因的刺激，Ｂ细胞处于休眠状态。在一定条件下，脐血ＮＫ细胞毒作用明     

mdr-1和DHFR双基因共转染人CD34+细胞拓宽造血细胞耐药谱的体外研究

目的　探讨将多药耐药基因 (mdr 1)和二氢叶酸还原酶基因 (DHFR)同时导入人CD3 4 细胞 ,以拓宽造血细胞耐药谱 ,改善骨髓耐受联合化疗的可行性。方法　将以造血细胞中高表达的逆转录病毒载体FMCF为基本结构骨架 ,通过引入IRES序列构建获得含mdr 1和DHFR(L2 2Y)双耐药基因的逆转录病毒载体pSF DIM ,通过脂质体介导包装 ,单嗜性和双嗜性包装细胞上清交叉感染提高病毒滴度。低温离心病毒上清转染人脐血CD3 4 细胞 ,用流式细胞仪检测P gp的表达 ,基因组PCR检测外源性耐药基因的整合 ,CFU GM培养观察耐药性变化。结果　逆转录病毒载体pSF DIM转导人脐血CD3 4 细胞后 ,P gp的表达较未转基因组增加了 10 .98% ;基因组PCR同时检测到两种外源性耐药基因的整合 ;与未转基因组比较 ,在 48nmol/L甲氨蝶呤和 10ng/ml及 12ng/ml紫杉醇 (商品名Taxol)浓度水平 ,CFU GM集落形成显著增加 (P <0 .0 5 )。结论　重组双耐药基因逆转录病毒载体pSF DIM可以有效介导mdr 1和DHFR双耐药基因进入人脐血CD3 4 细胞并且获得共表达 ,拓宽了造血细胞耐药谱     

mdr—1和DHFR双基因共转染入CD^＋34细胞拓宽造血细胞耐药谱的体外研究

目的：探讨将多药耐药基因（mdr-1)和二氢叶酸还原酶基因（DHFR)同时导入人CD^ 34细胞,以拓宽造血细胞耐药谱,改善骨髓耐受联合化疗的可行性,方法：将以造血细胞中高表达的逆转录病毒载体FMCF为基本结构骨架,通过引入IRES序列构建获得含mdr-1和DHFR（L22Y）双耐药基因的塑转录病毒载体pSF－DIM,通过脂质体介导包装,单嗜性和双 包装细胞上清交叉感染提高病毒滴度,低温离心病毒上清转染人脐血CD^ 34细胞,用流式细胞仪检测P－gp的表达,基因组PCR检测外源性耐药基因的整合,CFU－GM培养药性变化,结果：逆转录病毒载体pSF-DIM转人脐血CD^ 34细胞后,P-gp的表达较未转基因组增加了10．98％,基因组PCR同时检测到两种外源性药基因的整合,与未转基因组比较,在48nmol/L甲氢蝶呤和10ng/ml及12ng/ml紫杉醇（商品名Taxol）浓度水平,CFU－GM集落形成显著培养（P＜0．05）。结论：重组双耐药基因逆转录病毒载体pSF-DIM可度水平,CFU－GM集落形成显著增加（P＜0．05）,结论：重组双耐药基因逆转录病毒载体pSF-DIM可以有效介导mdr-1和DHFR双耐药基因进入人脐血CD34^ 细胞并获得共表达,拓宽了造血细胞药谱。     

High efficiency retroviral mediated gene transduction into single isolated immature and replatable CD34(3+) hematopoietic stem/progenitor cells from human umbilical cord blood

Umbilical cord blood is rich in hematopoietic stem and progenitor cells and has recently been used successfully in the clinic as an alternative source of engrafting and marrow repopulating cells. With the likelihood that cord blood stem/progenitor cells will be used for gene therapy to correct genetic disorders, we evaluated if a TK-neo gene could be directly transduced in a stable manner into single isolated subsets of purified immature hematopoietic cells that demonstrate self-renewed ability as estimated by colony replating capacity. Sorted CD34(3+) cells from cord blood were prestimulated with erythropoietin (Epo), steel factor (SLF), interleukin (IL)-3, and granulocyte-macrophage colony stimulating factor (GM-CSF) and transduced with the gene in two ways. CD34(3+) cells were incubated with retroviral-containing supernatant from TK-neo vector-producing cells, washed, and plated directly or resorted as CD34(3+) cells into single wells containing a single cell or 10 cells. Alternatively, CD34(3+) cells were sorted as a single cell/well and then incubated with viral supernatant. These cells were cultured with Epo, SLF, IL-3, and GM-CSF +/- G418. The TK-neo gene was introduced at very high efficiency into low numbers of or isolated single purified CD34(3+) immature hematopoietic cells without stromal cells as a source of virus or accessory cells. Proviral integration was detected in primary G418-resistant(R) colonies derived from single immature hematopoietic cells, and in cells from replated colonies derived from G418R-colony forming unit-granulocyte erythroid macrophage megakaryocyte (CFU-GEMM) and -high proliferative potential colony forming cells (HPP-CFC). This demonstrates stable expression of the transduced gene into single purified stem/progenitor cells with replating capacity, results that should be applicable for future clinical studies that may utilize selected subsets of stem/progenitor cells for gene therapy.     

双耐药基因导人脐血干/祖细胞降低联合化疗骨髓毒性作用的临床前研究

目的探讨转染醛脱氢酶基因(ALDH3)和多药耐药基因(mdr-1)的人脐血CD     

In vitro selection of lentivirus vector-transduced human CD34+ cells

Human CD34(+) cells with in vivo repopulating potential hold much promise as a target for corrective gene transfer for numerous hematopoietic disorders. However, the efficient introduction of exogenous genes into this small, quiescent population of cells continues to present a significant challenge. To circumvent the need for high initial transduction efficiency of human hematopoietic cells, we investigated a dominant selection strategy using a variant of the DHFR gene (DHFR(L22Y)). For this purpose, we constructed a lentivirus-based bicistronic vector expressing EGFP and DHFR(L22Y). Here we demonstrate efficient in vitro selection and enrichment of lentivirus vector-transduced human CD34(+) hematopoietic cells from fetal liver, umbilical cord blood, bone marrow, and peripheral blood after cytokine mobilization. Growth of transduced human CD34(+) cells in semisolid culture under selective pressure resulted in enrichment of transduced progenitor cells to 99.5% (n = 14). Selection for DHFR(L22Y)(+) cells after expansion of transduced progenitors in liquid culture resulted in a 7- to 13-fold increase in the percentage of marked cells. Thus we have shown that transduced human hematopoietic cells may be effectively enriched in vitro by dominant selection, suggesting that development of such strategies holds promise for future in vivo application.     

Efficient adenoviral vector transduction of human hematopoietic SCID-repopulating and long-term culture-initiating cells

This article presents our studies on the adenoviral transduction efficiency, level of transgene expression, cell cycle status, and multilineage reconstitution ability of human CD34+ hematopoietic cells transduced under proliferating and survival growth conditions. Bone marrow and umbilical cord blood CD34+ cells were cultured in serum-free medium under survival conditions with thrombopoietin (Tpo) alone, or under proliferating conditions with Tpo, c-Kit ligand (KL), and Flt3 ligand (FL). Adenoviral vectors carrying the enhanced green fluorescent protein (EGFP) gene under the control of the PGK-1 promoter were used to transduce CD34+ cells. Approximately 10% of CD34+ cells were EGFP+ under both culture conditions. In contrast, up to 50% of CD34+CD38- cells were EGFP+, whereas a maximum of 8% of CD34+CD38(high) cells were EGFP+ (p < 0.001). Both colony-forming unit cells (CFU-C) and 5-week long-term culture-initiating cells (LTC-ICs) were efficiently transduced. Under survival conditions, a substantial fraction of transduced CD34+ cells remained quiescent. The nondividing CD34+EGFP+ cells contained LTC-ICs capable of reconstituting longterm culture for as long as 10 weeks. CD34+EGFP+ cells also retained the ability to engraft and multilineage-reconstitute NOD/SCID mice. These observations demonstrate that primitive human hematopoietic progenitor cells can be efficiently transduced by adenoviral vectors.     

Adeno-associated virus 2-mediated high efficiency gene transfer into immature and mature subsets of hematopoietic progenitor cells in human umbilical cord blood

Recombinant adeno-associated virus 2 (AAV) virions were constructed containing a gene for resistance to neomycin (neoR), under the control of either the herpesvirus thymidine kinase (TK) gene promoter (vTK- Neo), or the human parvovirus B19 p6 promoter (vB19-Neo), as well as those containing an upstream erythroid cell-specific enhancer (HS-2) from the locus control region of the human beta-globin gene cluster (vHS2-TK-Neo; vHS2-B19-Neo). These recombinant virions were used to infect either low density or highly enriched populations of CD34+ cells isolated from human umbilical cord blood. In clonogenic assays initiated with cells infected with the different recombinant AAV-Neo virions, equivalent high frequency transduction of the neoR gene into slow-cycling multipotential, erythroid, and granulocyte/macrophage (GM) progenitor cells, including those with high proliferative potential, was obtained without prestimulation with growth factors, indicating that these immature and mature hematopoietic progenitor cells were susceptible to infection by the recombinant AAV virions. Successful transduction did not require and was not enhanced by prestimulation of these cell populations with cytokines. The functional activity of the transduced neo gene was evident by the development of resistance to the drug G418, a neomycin analogue. Individual high and low proliferative colony-forming unit (CFU)-GM, burst-forming unit-erythroid, and CFU- granulocyte erythroid macrophage megakaryocyte colonies from mock- infected, or the recombinant virus-infected cultures were subjected to polymerase chain reaction analysis using a neo-specific synthetic oligonucleotide primer pair. A 276-bp DNA fragment that hybridized with a neo-specific DNA probe on Southern blots was only detected in those colonies cloned from the recombinant virus-infected cells, indicating stable integration of the transduced neo gene. These studies suggest that parvovirus-based vectors may prove to be a useful alternative to the more commonly used retroviral vectors for high efficiency gene transfer into slow or noncycling primitive hematopoietic progenitor cells, without the need for growth factor stimulation, which could potentially lead to differentiation of these cells before transplantation.     

2型重组腺相关病毒对人脐血CD34+造血干/祖细胞的转导效率研究

为探讨 2型重组腺相关病毒 (rAAV 2 )载体能否有效地转导脐血CD34+造血干 /祖细胞 ,采用rAAV 2 /GFP感染经免疫磁珠法分离的脐血CD34+造血干 /祖细胞 ,在荧光显微镜下观察GFP的表达。结果显示 ,转导 19小时后感染复数 (MOI)为 2× 10 5时 ,CD34+细胞GFP基因的表达率为 4 3%。结论 :rAAV 2能有效地转导脐血CD34+造血干 /祖细胞。     

Retrovirus-mediated transfer of human alpha-galactosidase A gene to human CD34+ hematopoietic progenitor cells

Fabry disease, caused by a deficiency of lysosomal enzyme alpha-galactosidase A (alpha-gal A), is one of the inherited disorders potentially treatable by gene transfer to hematopoietic stem cells. In this study, a high-titer amphotropic retroviral producer cell line, MFG-alpha-gal A, was established. CD34+ cells from normal umbilical cord blood were transduced by centrifugal enhancement. The alpha-gal A activity in transduced cells increased 3.6-fold above the activity in nontransduced cells. Transduction efficiency measured by PCR for the integrated alpha-gal A cDNA in CFU-GM colonies was in the range of 42-88% (average, 63%). The expression of functional enzyme in TFI erythroleukemia was sustained for as long as cells remained in culture (84 days) and for 28 days in LTC-IC cultures of CD34+ cells. The ability of the transduced CD34+ cells to secrete the enzyme and to correct enzyme-deficient Fabry fibroblasts was assessed by cocultivation of these cells. The enzyme was secreted into the medium from transduced CD34+ cells and taken up by Fabry fibroblasts through mannose 6-phosphate receptors. These findings suggest that genetically corrected hematopoietic stem/progenitor cells can be an enzymatic source for neighboring enzyme-deficient cells, and can potentially be useful for gene therapy of Fabry disease.