scholarly journals 919. Gene Therapy for Platelet Disorders: Targeting Transgene Expression in Canine Platelets

2004 ◽  
Vol 9 ◽  
pp. S351-S352
Keyword(s):  
Gene Therapy ◽  
Transgene Expression ◽  
Platelet Disorders

Development of Megakaryocyte-Specific Lentiviral Vectors for Gene Therapy of Platelet Disorders.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 5143-5143
Author(s):  
Liesbeth De Waele ◽  
Kathleen Freson ◽  
Chantal Thys ◽  
Christel Van Geet ◽  
Désiré Collen ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Transgene Expression ◽  
Ex Vivo ◽  
Phosphoglycerate Kinase ◽  
Lentiviral Vectors ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Platelet Disorders

Abstract The prevalence of congenital platelet disorders has not been established but for some life-threatening bleeding disorders the current therapies are not adequate, justifying the development of alternative strategies as gene therapy. In the case of platelet dysfunction and thrombocytopenia as described for GATA1 deficiency, potentially lethal internal bleedings can occur. The objective of the study is to develop improved lentiviral vectors for megakaryocyte(MK)-specific long term gene expression by ex vivo transduction of hematopoietic stem cells (HSC) to ultimately use for congenital thrombopathies as GATA1 deficiency. Self-inactivating lentiviral vectors were constructed expressing GFP driven by the murine (m) or human (h) GPIIb promoter. These promoters contain multiple Ets and GATA binding sites directing MK-specificity. To evaluate the cell lineage-specificity and transgene expression potential of the vectors, murine Sca1+ and human CD34+ HSC were transduced in vitro with Lenti-hGPIIb-GFP and Lenti-mGPIIb-GFP vectors. After transduction the HSC were induced to differentiate in vitro along the MK and non-MK lineages. The mGPIIb and hGPIIb promoters drove GFP expression at overall higher levels (20% in murine cells and 25% in human cells) than the ubiquitous CMV (cytomegalovirus) or PGK (phosphoglycerate kinase) promoters, and this exclusively in the MK lineage. Interestingly, in both human and murine HSC the hGPIIb promoter with an extra RUNX and GATA binding site, was more potent in the MK lineage compared to the mGPIIb promoter. Since FLI1 and GATA1 are the main transcription factors regulating GPIIb expression, we tested the Lenti-hGPIIb-GFP construct in GATA1 deficient HSC and obtained comparable transduction efficiencies as for wild-type HSC. To assess the MK-specificity of the lentiviral vectors in vivo, we transplanted irradiated wild-type C57Bl/6 mice with Sca1+ HSC transduced with the Lenti-hGPIIb-GFP constructs. Six months after transplantation we could detect 6% GFP positive platelets without a GFP signal in other cell lineages. Conclusion: In vitro and in vivo MK-specific transgene expression driven by the hGPIIb and mGPIIb promoters could be obtained after ex vivo genetic engineering of HSC by improved lentiviral vectors. Studies are ongoing to study whether this approach can induce phenotypic correction of GATA1 deficient mice by transplantation of ex vivo Lenti-hGPIIb-GATA1 transduced HSC.

scholarly journals Hepatic DR5 Induces Apoptosis and Limits Adenovirus Gene Therapy Product Expression in the Liver

2002 ◽  
Vol 76 (11) ◽  
pp. 5692-5700 ◽  
Author(s):  
Huang-Ge Zhang ◽  
Jinfu Xie ◽  
Liang Xu ◽  
Pingar Yang ◽  
Xin Xu ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Immune Response ◽  
Transgene Expression ◽  
Cell Activation ◽  
Nk Cell ◽  
Death Domain ◽  
Activated T Cells ◽  
Tnf Α ◽  
Product Expression ◽  
Ifn Γ

ABSTRACT A major limitation of adenovirus (Ad) gene therapy product expression in the liver is subsequent elimination of the hepatocytes expressing the gene therapy product. This elimination is caused by both necrosis and apoptosis related to the innate and cell-mediated immune response to the Ad. Apoptosis of hepatocytes can be induced by the innate immune response by signaling through death domain receptors on hepatocytes including the tumor necrosis factor alpha (TNF-α) receptor (TNFR), Fas, and death domain receptors DR4 and DR5. We have previously shown that blocking signaling through TNFR enhances and prolongs gene therapy product expression in the liver. In the present study, we constructed an Ad that produces a soluble DR5-Fc (AdsDR5), which is capable of neutralizing TNF-related apoptosis-inducing ligand (TRAIL). AdsDR5 prevents TRAIL-mediated apoptosis of CD3-activated T cells and decreases hepatocyte apoptosis after AdCMVLacZ administration and enhances the level and duration of lacZ transgene expression in the liver. In addition to blocking TRAIL and directly inhibiting apoptosis, AdsDR5 decreases production of gamma interferon (IFN-γ) and TNF-α and decreases NK cell activation, all of which limit Ad-mediated transgene expression in the liver. These results indicate that (i) AdsDR5 produces a DR5-Fc capable of neutralizing TRAIL, (ii) AdsDR5 can reduce activation of NK cells and reduce induction of IFN-γ and TNF-α after Ad administration, and (iii) administration of AdsDR5 can enhance Ad gene therapy in the liver.

scholarly journals Foamy Virus Vector Carries a Strong Insulator in Its Long Terminal Repeat Which Reduces Its Genotoxic Potential

2017 ◽  
Vol 92 (1) ◽  
Author(s):  
Michael Aaron Goodman ◽  
Paritha Arumugam ◽  
Devin Marie Pillis ◽  
Anastacia Loberg ◽  
Mohammed Nasimuzzaman ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Long Terminal Repeat ◽  
Transgene Expression ◽  
Viral Vectors ◽  
Foamy Virus ◽  
Terminal Repeat ◽  
Genotoxic Potential ◽  
Binding Factor ◽  
Activation Assay ◽  
Lentivirus Vectors

ABSTRACTStrong viral enhancers in gammaretrovirus vectors have caused cellular proto-oncogene activation and leukemia, necessitating the use of cellular promoters in “enhancerless” self-inactivating integrating vectors. However, cellular promoters result in relatively low transgene expression, often leading to inadequate disease phenotype correction. Vectors derived from foamy virus, a nonpathogenic retrovirus, show higher preference for nongenic integrations than gammaretroviruses/lentiviruses and preferential integration near transcriptional start sites, like gammaretroviruses. We found that strong viral enhancers/promoters placed in foamy viral vectors caused extremely low immortalization of primary mouse hematopoietic stem/progenitor cells compared to analogous gammaretrovirus/lentivirus vectors carrying the same enhancers/promoters, an effect not explained solely by foamy virus' modest insertional site preference for nongenic regions compared to gammaretrovirus/lentivirus vectors. Using CRISPR/Cas9-mediated targeted insertion of analogous proviral sequences into theLMO2gene and then measuringLMO2expression, we demonstrate a sequence-specific effect of foamy virus, independent of insertional bias, contributing to reduced genotoxicity. We show that this effect is mediated by a 36-bp insulator located in the foamy virus long terminal repeat (LTR) that has high-affinity binding to the CCCTC-binding factor. Using our LMO2 activation assay,LMO2expression was significantly increased when this insulator was removed from foamy virus and significantly reduced when the insulator was inserted into the lentiviral LTR. Our results elucidate a mechanism underlying the low genotoxicity of foamy virus, identify a novel insulator, and support the use of foamy virus as a vector for gene therapy, especially when strong enhancers/promoters are required.IMPORTANCEUnderstanding the genotoxic potential of viral vectors is important in designing safe and efficacious vectors for gene therapy. Self-inactivating vectors devoid of viral long-terminal-repeat enhancers have proven safe; however, transgene expression from cellular promoters is often insufficient for full phenotypic correction. Foamy virus is an attractive vector for gene therapy. We found foamy virus vectors to be remarkably less genotoxic, well below what was expected from their integration site preferences. We demonstrate that the foamy virus long terminal repeats contain an insulator element that binds CCCTC-binding factor and reduces its insertional genotoxicity. Our study elucidates a mechanism behind the low genotoxic potential of foamy virus, identifies a unique insulator, and supports the use of foamy virus as a vector for gene therapy.

scholarly journals Evaluation of Transduction Properties of an Adenovirus Vector in Neonatal Mice

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Shunsuke Iizuka ◽  
Fuminori Sakurai ◽  
Kahori Shimizu ◽  
Kazuo Ohashi ◽  
Shin-ichiro Nakamura ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Transgene Expression ◽  
Adenovirus Vector ◽  
Firefly Luciferase ◽  
Luciferase Expression ◽  
Cmv Promoter ◽  
Neonatal Mice ◽  
Neonatal Heart ◽  
Neonatal Liver ◽  
Neonates And Infants

In gene therapy for congenital disorders, treatments during neonate and infant stages are promising. Replication-incompetent adenovirus (Ad) vectors have been used in gene therapy studies of genetic disorders; however, the transduction properties of Ad vectors in neonates and infants have not been fully examined. Accordingly, this study examined the properties of Ad vector-mediated transduction in neonatal mice. A first-generation Ad vector containing a cytomegalovirus (CMV) promoter-driven luciferase expression cassette was administered to neonatal mice on the second day of lifeviaretro-orbital sinus. The highest Ad vector genome copy numbers and transgene expression were found in the neonatal liver. The neonatal heart exhibited the second highest levels of transgene expression among the organs examined. There was an approximately 1500-fold difference in the transgene expression levels between the adult liver and heart, while the neonatal liver exhibited only an approximately 30-fold higher level of transgene expression than the neonatal heart. A liver-specific promoter for firefly luciferase expression conferred a more than 100-fold higher luciferase expression in the liver relative to the other organs. No apparent hepatotoxicity was observed in neonatal mice following Ad vector administration. These findings should provide valuable information for gene therapy using Ad vectors in neonates and infants.

scholarly journals Evading the AAV Immune Response in Mucopolysaccharidoses

2020 ◽  
Vol 21 (10) ◽  
pp. 3433
Author(s):  
Matthew Piechnik ◽  
Kazuki Sawamoto ◽  
Hidenori Ohnishi ◽  
Norio Kawamoto ◽  
Yasuhiko Ago ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Immune Response ◽  
Humoral Immune Response ◽  
Transgene Expression ◽  
Evidence Based ◽  
Adeno Associated Virus ◽  
Gene Therapies ◽  
Humoral Immune ◽  
Significant Challenge ◽  
Racial Background

The humoral immune response elicited by adeno-associated virus (AAV)-mediated gene therapy for the treatment of mucopolysaccharidoses (MPS) poses a significant challenge to achieving therapeutic levels of transgene expression. Antibodies targeting the AAV capsid as well as the transgene product diminish the production of glycosaminoglycan (GAG)-degrading enzymes essential for the treatment of MPS. Patients who have antibodies against AAV capsid increase in number with age, serotype, and racial background and are excluded from the clinical trials at present. In addition, patients who have undergone AAV gene therapy are often excluded from the additional AAV gene therapy with the same serotype, since their acquired immune response (antibody) against AAV will limit further efficacy of treatment. Several methods are being developed to overcome this immune response, such as novel serotype design, antibody reduction by plasmapheresis and immunosuppression, and antibody evasion using empty capsids and enveloped AAV vectors. In this review, we examine the mechanisms of the anti-AAV humoral immune response and evaluate the strengths and weaknesses of current evasion strategies in order to provide an evidence-based recommendation on evading the immune response for future AAV-mediated gene therapies for MPS.

scholarly journals A Double-Switch Cell Fusion-Inducible Transgene Expression System for Neural Stem Cell-Based Antiglioma Gene Therapy

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Yumei Luo ◽  
Detu Zhu ◽  
Dang Hoang Lam ◽  
Juan Huang ◽  
Yi Tang ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Stem Cell ◽  
Neural Stem Cell ◽  
Cell Fusion ◽  
Transgene Expression ◽  
Glioma Cell ◽  
Expression System ◽  
Glioma Cells ◽  
Luciferase Reporter ◽  
Double Switch

Recent progress in neural stem cell- (NSC-) based tumor-targeted gene therapy showed that NSC vectors expressing an artificially engineered viral fusogenic protein, VSV-G H162R, could cause tumor cell death specifically under acidic tumor microenvironment by syncytia formation; however, the killing efficiency still had much room to improve. In the view that coexpression of another antitumoral gene with VSV-G can augment the bystander effect, a synthetic regulatory system that triggers transgene expression in a cell fusion-inducible manner has been proposed. Here we have developed a double-switch cell fusion-inducible transgene expression system (DoFIT) to drive transgene expression upon VSV-G-mediated NSC-glioma cell fusion. In this binary system, transgene expression is coregulated by a glioma-specific promoter and targeting sequences of a microRNA (miR) that is highly expressed in NSCs but lowly expressed in glioma cells. Thus, transgene expression is “switched off” by the miR in NSC vectors, but after cell fusion with glioma cells, the miR is diluted and loses its suppressive effect. Meanwhile, in the syncytia, transgene expression is “switched on” by the glioma-specific promoter. Ourin vitroandin vivoexperimental data show that DoFIT successfully abolishes luciferase reporter gene expression in NSC vectors but activates it specifically after VSV-G-mediated NSC-glioma cell fusion.

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