Neonatal helper-dependent adenoviral vector gene therapy mediates correction of hemophilia A and tolerance to human factor VIII

Neonatal gene therapy is a promising strategy for treating a number of congenital diseases diagnosed shortly after birth as expression of therapeutic proteins during postnatal life may limit the pathologic consequences and result in a potential "cure." Hemophilia A is often complicated by the development of antibodies to recombinant protein resulting in treatment failure. Neonatal administration of vectors may avoid inhibitory antibody formation to factor VIII (FVIII) by taking advantage of immune immaturity. A helper-dependent adenoviral vector expressing human factor VIII was administered i.v. to neonatal hemophilia A knockout mice. Three days later, mice produced high levels of FVIII. Levels declined rapidly with animal growth to 5 wk of age with stable factor VIII expression thereafter to >1 y of age. Decline in factor VIII expression was not related to cell-mediated or humoral responses with lack of development of antibodies to capsid or human factor VIII proteins. Subsequent readministration and augmentation of expression was possible as operational tolerance was established to factor VIII without development of inhibitors; however, protective immunity to adenovirus remained.     

Sustained correction of bleeding disorder in hemophilia B mice by gene therapy

Mice generated by disrupting the clotting factor IX gene exhibit severe bleeding disorder and closely resemble the phenotype seen in hemophilia B patients. Here we demonstrate that a single intraportal injection of a recombinant adeno-associated virus (AAV) vector encoding canine factor IX cDNA under the control of a liver-specific enhancer/promoter leads to a long-term and complete correction of the bleeding disorder. High level expression of up to 15-20 microgram/ml of canine factor IX was detected in the plasma of mice injected with 5.6 x 10(11) particles of an AAV vector for >5 months. The activated partial thromboplastin time of the treated mice was fully corrected to higher than normal levels. Liver-specific expression of canine factor IX was confirmed by immunofluorescence staining, and secreted factor IX protein was identified in the mouse plasma by Western blotting. All treated mice survived the tail clip test without difficulty. Thus, a single intraportal injection of a recombinant adeno-associated virus vector expressing factor IX successfully cured the bleeding disorder of hemophilia B mice, proving the feasibility of using AAV-based vectors for liver-targeted gene therapy of genetic diseases.     

A gene-deleted adenoviral vector results in phenotypic correction of canine hemophilia B without liver toxicity or thrombocytopenia

Many approaches for treating hemophilia via gene transfer have been attempted in large animal models but all have potential drawbacks. Recombinant adenoviral vectors offer high-efficiency transfer of an episomal vector but have been plagued by the cytotoxicity/immunogenicity of early-generation vectors that contain viral genes. In our current study, we have used a nonintegrating helper-dependent (HD) adenoviral vector for liver-directed gene transfer to achieve hemostatic correction in a dog with hemophilia B. We measured plasma canine factor IX (cFIX) concentrations at a therapeutic range for up to 2.5 months and normalization of the whole blood clotting time (WBCT) for about a month. This was followed by a decrease and stabilized partial correction for 4.5 months. Hepatic gene transfer of a slightly lower dose of the HD vector resulted in WBCTs that were close to normal for 2 weeks, suggesting a dose threshold effect in dogs. In sharp contrast to other studies using first- or second-generation adenoviral vectors, we observed no vector-related elevation of liver enzymes, no fall in platelet counts, and normal liver histology. Taken together, this study demonstrates that injection of an adenoviral HD vector results in complete but transient phenotypic correction of FIX deficiency in canine models with no detectable toxicity.     

Sustained phenotypic correction of canine hemophilia A using an adeno-associated viral vector

Gene therapy for hemophilia A requires efficient delivery of the factor VIII gene and sustained protein expression at circulating levels of at least 1% to 2% of normal. Adeno-associated viral type 2 (AAV2) vectors have a number of advantages over other viral vectors, including an excellent safety profile and persistent gene expression. However, a major disadvantage is their small packaging capacity, which has hampered their use in treating diseases such as hemophilia A, cystic fibrosis, and muscular dystrophy, which are caused by mutations in large genes. Here we demonstrate that this can be overcome by using small regulatory elements to drive expression of a B-domain-deleted form of FVIII. The use of this vector for hepatic gene transfer in a canine model of hemophilia A resulted in the sustained (> 14 months) expression of biologically active FVIII. FVIII activity levels of 2% to 4% were achieved. These levels correlated with a partial correction in the whole-blood clotting time and cuticle bleeding time. In addition, immunoprecipitation analysis demonstrated the expression of canine FVIII of the predicted size in the plasma of injected animals. These data support the use of AAV2 vectors in human clinical trials to treat hemophilia A patients.     

Permanent phenotypic correction of hemophilia B in immunocompetent mice by prenatal gene therapy

Hemophilia B, also known as Christmas disease, arises from mutations in the factor IX (F9) gene. Its treatment in humans, by recombinant protein substitution, is expensive, thus limiting its application to intermittent treatment in bleeding episodes and prophylaxis during surgery; development of inhibitory antibodies is an associated hazard. This study demonstrates permanent therapeutic correction of his disease without development of immune reactions by introduction of an HIV-based lentiviral vector encoding the human factor IX protein into the fetal circulation of immunocompetent hemophiliac and normal outbred mice. Plasma factor IX antigen remained at around 9%, 13%, and 16% of normal in the 3 hemophilia B mice, respectively, until the last measurement at 14 months. Substantial improvement in blood coagulability as measured by coagulation assay was seen in all 3 mice and they rapidly stopped bleeding after venipuncture. No humoral or cellular immunity against the protein, elevation of serum liver enzymes, or vector spread to the germline or maternal circulation were detected.     

Hepatitis B virus inhibition in mice by lentiviral vector mediated short hairpin RNA

Background  

Chronic hepatitis B virus (HBV) infection is an important cause of cirrhosis and hepatocellular carcinoma. The major challenges for current therapies are the low efficacy of current drugs and the occurrence of drug resistant HBV mutations. RNA interference (RNAi) of virus-specific genes offers the possibility of developing a new anti-HBV therapy. Recent reports have shown that lentiviral vectors based on HIV-1 are promising gene delivery vehicles due to their ability to integrate transgenes into non-dividing cells. Herein, a lentivirus-based RNAi system was developed to drive expression and delivery of HBV-specific short hairpin RNA (shRNA) in a mouse model for HBV replication.     

Successful correction of the human beta-thalassemia major phenotype using a lentiviral vector

beta-thalassemias are the most common single gene disorders and are potentially amenable to gene therapy. However, retroviral vectors carrying the human beta-globin cassette have been notoriously unstable. Recently, considerable progress has been made using lentiviral vectors, which stably transmit the beta-globin expression cassette. Thus far, mouse studies have shown correction of the beta-thalassemia intermedia phenotype and a partial, variable correction of beta-thalassemia major phenotype. We tested a lentiviral vector carrying the human beta-globin expression cassette flanked by a chromatin insulator in transfusion-dependent human thalassemia major, where it would be ultimately relevant. We demonstrated that the vector expressed normal amounts of human beta-globin in erythroid cells produced in in vitro cultures for unilineage erythroid differentiation. There was restoration of effective erythropoiesis and reversal of the abnormally elevated apoptosis that characterizes beta-thalassemia. The gene-corrected human beta-thalassemia progenitor cells were transplanted into immune-deficient mice, where they underwent normal erythroid differentiation, expressed normal levels of human beta-globin, and displayed normal effective erythropoiesis 3 to 4 months after xenotransplantation. Variability of beta-globin expression in erythroid colonies derived in vitro or from xenograft bone marrow was similar to that seen in normal controls. Our results show genetic modification of primitive progenitor cells with correction of the human thalassemia major phenotype.     

Total correction of hemophilia A mice with canine FVIII using an AAV 8 serotype

Despite the popularity of adeno-associated virus 2 (AAV2) as a vehicle for gene transfer, its efficacy for liver-directed gene therapy in hemophilia A or B has been suboptimal. Here we evaluated AAV serotypes 2, 5, 7, and 8 in gene therapy of factor VIII (FVIII) deficiency in a hemophilia A mouse model and found that AAV8 was superior to the other 3 serotypes. We expressed canine B domain-deleted FVIII cDNA either in a single vector or in 2 separate AAV vectors containing the heavy- and light-chain cDNAs. We also evaluated AAV8 against AAV2 in intraportal and tail vein injections. AAV8 gave 100% correction of plasma FVIII activity irrespective of the vector type or route of administration.     

微小RNA-1慢病毒载体介导大鼠骨髓间充质干细胞分化为心肌样细胞的研究

目的通过微小RNA-1(microRNA-1,miR-1)慢病毒载体转染大鼠骨髓间充质干细胞(MSC),探讨miR-1对MSC向心肌细胞分化的影响。方法采用全骨髓贴壁培养法分离培养大鼠MSC并进行流式细胞学鉴定;构建表达miR-1慢病毒载体;将miR-1慢病毒载体转染大鼠MSC(MSCmiR-1)连续培养15d,光镜下观察转染后细胞形态,分别于0、4、6、15dqRT-PCR检测miR-1、心肌相关基因锌指结构蛋白(GATA-4)、肌钙蛋白I(cTnI)、α肌动蛋白(α-actin)的表达;免疫荧光观察cTnI的表达;Western blot检测α-actin的表达。结果原代大鼠MSC呈长梭形、漩涡状生长,流式细胞学检测显示,98%以上细胞表达CD44和CD29,不足1%细胞表达CD45;成功构建miR-1重组慢病毒载体,病毒滴度为3×108 TU/μl;转导miR-1后,MSCmiR-1高表达心肌特异性相关基因GATA-4、α-actin、cTnI,并随时间逐渐增强,转染4d免疫荧光检测可见cTnI在部分MSCmiR-1中表达,于15d时表达最强,Westernblot进一步证实了α-actin在MSCmiR-1中表达。结论转导miR-1至大鼠MSC中可促使其向心肌样细胞的分化。     

小鼠肝细胞SMAC基因特异干扰载体的构建及慢病毒包装

目的构建并鉴定小鼠SMAC特异干扰载体,并进行慢病毒包装。方法针对小鼠SMAC基因设计并合成3对干扰序列siRNA1、siRNA2、siRNA3及一对阴性对照序列siRNAn,脂质体法转染小鼠肝细胞,Real time PCR法筛选出最佳干扰序列。依据该最佳干扰序列合成DNA oligo,连接GV115载体,获得重组干扰质粒,PCR鉴定阳性克隆并测序鉴定构建的正确性。将该重组干扰质粒与辅助质粒pHelper1.0和pHelper2.0共转染293T细胞,进行慢病毒包装,收集细胞上清并浓缩,梯度稀释法测定病毒滴度。多组间比较采用方差分析,进一步两两比较采用SNK-q检验。结果 3条siRNA对肝细胞SMAC mRNA均有不同程度的抑制作用,其中siRNA1的抑制效应最强,抑制效率达到70.3%。依siRNA1片段合成DNA oligo,并与慢病毒载体连接,测序显示其构建正确,梯度稀释法测定慢病毒滴度为6×108TU/ml。结论成功构建了小鼠SMAC基因特异干扰性的慢病毒,为研究SMAC基因在肝衰竭中的作用奠定基础。     

Homologous recombination mediates stable Fah gene integration and phenotypic correction in tyrosinaemia mouse-model

AIM To stably correct tyrosinaemia in proliferating livers of fumarylacetoacetate-hydrolase knockout(Fah-/-) mice by homologous-recombination-mediated targeted addition of the Fah gene.METHODS C57 BL/6 Fah?exon5 mice served as an animal model for human tyrosinaemia type 1 in our study. The vector was created by amplifying human Fah c DNA including the TTR promoter from a lentivirus plasmid as described. The Fah expression cassette was flanked by homologous arms(620 bp and 749 bp long) of the Rosa26 gene locus. Mice were injected with 2.1 × 108 VP of this vector(r AAV8-ROSA26.HAL-TTR.FahROSA26.HAR) via the tail vein. Mice in the control group were injected with 2.1 × 108 VP of a similar vector but missing the homologous arms(r AAV8-TTR.Fah). Primary hepatocytes from Fah-/-recipient mice, treated with our vectors, were isolated and 1 × 106 hepatocytes were transplanted into secondary Fah-/-recipient mice by injection into the spleen. Upon either vector application or hepatocyte transplantation NTBC treatment was stopped in recipient mice. RESULTS Here, we report successful HR-mediated genome editing by integration of a Fah gene expression cassette into the "safe harbour locus" Rosa26 by recombinant AAV8. Both groups of mice showed long-term survival, weight gain and FAH positive clusters as determined by immunohistochemistry analysis of liver sections in the absence of NTBC treatment. In the group of C57 BL/6 Fah?exon5 mice, which have been transplanted with hepatocytes from a mouse injected with r AAV8-ROSA26.HAL-TTR.Fah-ROSA26.HAR 156 d before, 6 out of 6 mice showed long-term survival, weight gain and FAH positive clusters without need for NTBC treatment. In contrast only 1 out 5 mice, who received hepatocytes from r AAV8-TTR.Fah treated mice, survived and showed few and smaller FAH positive clusters. These results demonstrate that homologous recombinationmediated Fah gene transfer corrects the phenotype in a mouse model of human tyrosinaemia type 1(Fah-/-mice) and is long lasting in a proliferating state of the liver as shown by withdrawal of NTBC treatment and serial transplantation of isolated hepatocytes from primary Fah-/-recipient mice into secondary Fah-/-recipient mice. This long term therapeutic efficacy is clearly superior to our control mice treated with episomal r AAV8 gene therapy approach.CONCLUSION HR-mediated r AAV8 gene therapy provides targeted transgene integration and phenotypic correction in Fah-/-mice with superior long-term efficacy compared to episomal r AAV8 therapy in proliferating livers.     

细胞外基质金属蛋白酶诱导因子RNAi慢病毒载体的构建

目的构建人细胞外基质金属蛋白酶诱导因子（EMMPRIN）RNA干扰（RNAi）慢病毒载体。方法参照文献设计RNAi靶点序列,合成靶序列的Oligo DNA,退火形成双链DNA,与经AgeⅠ和EcoRⅠ酶切后的pGCSIL-GFP载体连接产生RNAi慢病毒载体pGC-LV。PCR鉴定阳性克隆并测序,将测序正确的pGC-LV、pHelper 1.0和pHelper 2.0质粒经脂质体2000共转染293T细胞,获得重组慢病毒,用逐孔稀释法测定病毒滴度。结果合成的含EMMPRIN vshRNA慢病毒载体寡核苷酸链插入正确;病毒包装后滴度为1×109 TU/ml。结论应用基因工程技术成功构建了可供感染的EMMPRIN基因RNAi慢病毒载体,此为进一步研究EMMPRIN在急性白血病中的作用奠定了实验基础。     

A highly efficient,stable, and rapid approach for ex vivo human liver gene therapy via a FLAP lentiviral vector

Allogenic hepatocyte transplantation or autologous transplantation of genetically modified hepatocytes has been used successfully to correct congenital or acquired liver diseases and can be considered as an alternative to orthotopic liver transplantation. However, hepatocytes are neither easily maintained in culture nor efficiently genetically modified and are very sensitive to dissociation before their reimplantation into the recipient. These difficulties have greatly limited the use of an ex vivo approach in clinical trials. In the present study, we have shown that primary human and rat hepatocytes can be efficiently transduced with a FLAP lentiviral vector without the need for plating and culture. Efficient transduction of nonadherent primary hepatocytes was achieved with a short period of contact with vector particles, without modifying hepatocyte viability, and using reduced amounts of vector. We also showed that the presence of the DNA FLAP in the vector construct was essential to reach high levels of transduction. Moreover, transplanted into uPA/SCID mouse liver, lentivirally transduced primary human hepatocytes extensively repopulated their liver and maintained a differentiated and functional phenotype as assessed by the stable detection of human albumin and antitrypsin in the serum of the animals for months. In conclusion, the use of FLAP lentiviral vectors allows, in a short period of time, a high transduction efficiency of human functional and reimplantable hepatocytes. This work therefore opens new perspectives for the development of human clinical trials based on liver-directed ex vivo gene therapy.     

携带Foxp3基因慢病毒载体的构建

目的构建携带叉头样转录因子p3（Foxp3）基因的重组慢病毒载体PWPXL-MOD-Foxp3,并包装成慢病毒,为体外获得CD4＋CD2＋5调节性T细胞（CD4＋CD2＋5 Tregs）奠定基础。方法采用双酶切法构建慢病毒表达载体PWPXL-MOD-Foxp3,用磷酸钙沉淀法将包装慢病毒所需的四质粒系统共转染人胚肾细胞293T,慢病毒系统转染48h后收集病毒上清液,纯化、浓缩后采用流式细胞术测定慢病毒滴度。结果重组的慢病毒载体滴度为3.3×108IU/ml。结论成功构建了含有Foxp3基因的高滴度的慢病毒载体,为体外获得CD 4＋CD 2＋5 Tregs奠定基础。     

人肿瘤抑素Tumstatin基因慢病毒表达载体的构建及其蛋白表达

目的 构建Tumstatin基因慢病毒表达载体,进一步研究Tumstatin基因的功能及其在肿瘤治疗中的应用.方法 采用PCR技术从含有Tumstatin基因的质粒pSPORT1-Sfi扩增目的 基因Tumstatin,并将基因克隆到慢病毒载体表达质粒PGC-Fu[含增强型绿色荧光蛋白(EGFP)基因]中,构建慢病毒载体表达质粒pGC-FU-Tum,通过酶切、测序验证Tumstatin基因后,将pGC-FU-Tum质粒和包装质粒pHelper1.0、pHelpe2.0共同转染人胚胎肾上皮细胞系293T细胞,获得携带Tumstatin基因和EGFP基因的重组慢病毒GC-Fu-Tum,并转染人脐静脉血管内皮细胞HUVEC,Wstem blot检测目的 蛋白Tumstatin的表达.结果 pGC-FU-Tum中携有正确的Tumstatin基因;pGC-FUTurn共转染包装细胞293T能产生高浓度的重组慢病毒GC-FU-Tum;目的 基因Tumstatin能被重组慢病毒高效地转导入HUVEC,荧光显微镜下能直接观察到EGFP,Western blot能检测到Tumstatin蛋白在靶细胞中的表达.结论 成功构建了携带Tumstatin基因的重组慢病毒载体;其蛋白表达与EGFP-致..     

Complete short-term correction of canine hemophilia A by in vivo gene therapy

Hemophilia A is a severe bleeding disorder caused by a deficiency in clotting factor VIII (FVIII). A canine model that closely mimics the human disease was used to determine if an adenoviral vector expressing a human FVIII cDNA could be used to correct the hemophilia A phenotype. Within 48 hours after peripheral vein administration of the vector to FVIII-deficient dogs, the hemophilic phenotype was corrected, based on determination of the activated clotting time, the activated partial thromboplastin time, and the cuticle bleeding time. Direct measurement of human FVIII in the dog plasma showed FVIII expression at amounts well above the human therapeutic level. FVIII expression in treated dogs was short-term, lasting 1 to 2 weeks, due to the development of a human FVIII-specific inhibitor antibody response. These data provide the first demonstration of in vivo gene therapy of hemophilia A.     

Discrepant ratios of arterial versus venous thrombosis in hemophilia A as compared with hemophilia B

The occurrence of thrombosis in patients with congenital bleeding disorders represents an exceptional event. Hemophilia A and hemophilia B patients have been showed to present both arterial and venous thrombosis (85 cases of arterial thrombosis and 34 cases of venous thrombosis). The great majority of arterial thrombosis are myocardial infarction or other acute coronary syndromes, whereas the majority of venous thrombosis are deep vein thrombosis and/or pulmonary embolisms. However there are discrepancies in the proportion of arterial and venous thrombosis seen in hemophilia A versus hemophilia B. The ratio of arterial versus venous thrombosis in hemophilia A is 3.72 whereas that for hemophilia B is 1.12. This indicates that arterial thrombosis is more frequent in hemophilia A as compared to hemophilia B and the opposite is true for venous thrombosis. The potential significance of this discrepancy is discussed.