28. Intravenous Administration of Lentiviral Vectors Expressing Hyperactive Factor IX Converts Severe Into Mild Hemophilia B in a Canine Model

Lentiviral vectors (LVs) are attractive vehicles for liver-directed gene therapy by virtue of their ability to stably integrate in the genome of target cells and the lack of pre-existing immunity against vector components in most humans. Over the past years, we have developed a LV platform that can achieve stable transgene expression in the liver, induce transgene-specific immune tolerance and establish correction of hemophilia in mouse models upon systemic administration. This LV is designed to stringently target transgene expression to hepatocytes through transcriptional and microRNA-mediated regulation. We then investigated the efficacy and safety profile of portal vein administration of LVs expressing wild-type, codon-optimized (c.o.) or c.o. and hyperactive factor IX (FIX) in a canine model of hemophilia B. We produced large-scale batches of LVs qualified for in vivo administration and treated adult hemophilia B dog by portal vein administration. We observed long-term stable reconstitution of canine FIX activity up to 1% of normal and significant amelioration of the clinical phenotype in 3 treated dogs (>9 years cumulative follow up). LV infusion was associated with transient signs of inflammation and mild hepatotoxicity, which could be abrogated by pretreatment with anti-inflammatory drugs. There was no detectable long-term toxicity or development of FIX inhibitors. In the perspective of clinical translation and to increase therapeutic efficacy, we next treated an 11-kg, hemophilia B dog by peripheral vein administration of LVs expressing the c.o. and hyperactive canine FIX at a 5-fold higher dose than those previously administered. At the current follow-up (3 months after gene therapy) FIX activity is 6-9% of normal. Intravenous LV administration, coupled with a 1-day anti-inflammatory and anti-histamine pre-treatment, induced mild and selflimiting leukopenia and elevation of aminotransferases. Treatment of more hemophilia B dogs is underway to confirm and extend these results. Overall, our studies, which suggest comparable efficacy of LV by both portal and peripheral vein administration, position LV-mediated liver gene therapy for further pre-clinical development and clinical translation. LVs may thus complement other available vectors to address some of the outstanding challenges posed by liver gene therapy of hemophilia and conceivably other diseases

756 stable amelioration of hemophilia b in dogs by intravenous administration of lentiviral vectors expressing hyper functional factor ix

Lentiviral vectors (LVs) are attractive vehicles for liver-directed gene therapy by virtue of their ability to stably integrate in the genome of target cells and the low prevalence of pre-existing immunity against HIV in humans. Over the past years, we have developed a LV platform that can achieve stable transgene expression in the liver, induce transgene-specific immune tolerance and establish correction of hemophilia in mouse models upon systemic administration. This LV is designed to stringently target transgene expression to hepatocytes through transcriptional and microRNA-mediated regulation. We then investigated the efficacy and safety profile of portal vein administration of LVs expressing canine factor IX (FIX) in a canine model of hemophilia B. We produced large-scale batches of LVs qualified for in vivo administration and treated adult hemophilia B dog by portal vein administration. We observed long-term stable reconstitution of canine FIX activity up to 1% of normal and significant amelioration of the clinical phenotype in 3 treated dogs with 6, 3.5 and 2.5 years of follow up. LV infusion was associated with transient signs of inflammatory response and mild hepatotoxicity, which could be abrogated by pretreatment with anti-inflammatory drugs. There was no detectable long-term toxicity or development of FIX inhibitors. In the perspective of clinical translation and to increase therapeutic efficacy, we next treated two 10-kg hemophilia B dogs by peripheral vein administration of LVs expressing a codon-optimized and hyperfunctional canine FIX at a 5-fold higher dose than those previously administered. Intravenous LV administration was well tolerated with mild and self-limiting elevation of aminotransferases in one dog. In the dog that reached more than 1 year of follow up FIX activity ranged between 4-8% of normal. Treatment of two more dogs at a higher dose is underway. Overall, our studies position LV-mediated liver gene therapy for further pre-clinical development and clinical translation. LVs may thus complement other available vectors to address some of the outstanding challenges posed by liver gene therapy of hemophilia and conceivably other diseases

Genome-wide computational analysis reveals cardiomyocyte-specific transcriptional cis-regulatory motifs that enable efficient cardiac gene therapy

Gene therapy is a promising emerging therapeutic modality for the treatment of cardiovascular diseases and hereditary diseases that afflict the heart. Hence, there is a need to develop robust cardiac-specific expression modules that allow for stable expression of the gene of interest in cardiomyocytes. We therefore explored a new approach based on a genome-wide bioinformatics strategy that revealed novel cardiac-specific cis-acting regulatory modules (CS-CRMs). These transcriptional modules contained evolutionary-conserved clusters of putative transcription factor binding sites that correspond to a "molecular signature" associated with robust gene expression in the heart. We then validated these CS-CRMs in vivo using an adeno-associated viral vector serotype 9 that drives a reporter gene from a quintessential cardiac-specific a-myosin heavy chain promoter. Most de novo designed CS-CRMs resulted in a > 10-fold increase in cardiac gene - expression. The most robust CRMs enhanced cardiac-specific transcription 70- to 100-fold. Expression was sustained and restricted to cardiomyocytes. We then combined the most potent CS-CRM4 with a synthetic heart and muscle-specific promoter (SPc5-12) and obtained a significant 20-fold increase in cardiac gene expression compared to the cytomegalovirus promoter. This study underscores the potential of rational vector design to improve the robustness of cardiac gene therapy

Korkunç İstanbul

Yeni Türk'te tefrika edilen Korkunç İstanbul adlı romanTefrikada yazarın adı belirtilmemiştir.Tefrika yarım kalmıştır. Arşivdeki eksikler nedeniyle tefrikanın tamamlanıp tamamlanmadığı bilinmemektedir

<i>piggyBac </i>transposons expressing full-length human dystrophin enable genetic correction of dystrophic mesoangioblasts

Duchenne muscular dystrophy (DMD) is a genetic neuromuscular disorder caused by the absence of dystrophin. We developed a novel gene therapy approach based on the use of the piggyBac (PB) transposon system to deliver the coding DNA sequence (CDS) of either full-length human dystrophin (DYS: 11.1 kb) or truncated microdystrophins (MD1: 3.6 kb; MD2: 4 kb). PB transposons encoding microdystrophins were transfected in C2C12 myoblasts, yielding 65±2% MD1 and 66±2% MD2 expression in differentiated multinucleated myotubes. A hyperactive PB (hyPB) transposase was then deployed to enable transposition of the large-size PB transposon (17 kb) encoding the full-length DYS and green fluorescence protein (GFP). Stable GFP expression attaining 78±3% could be achieved in the C2C12 myoblasts that had undergone transposition. Western blot analysis demonstrated expression of the full-length human DYS protein in myotubes. Subsequently, dystrophic mesoangioblasts from a Golden Retriever muscular dystrophy dog were transfected with the large-size PB transposon resulting in 50±5% GFP-expressing cells after stable transposition. This was consistent with correction of the differentiated dystrophic mesoangioblasts following expression of full-length human DYS. These results pave the way toward a novel non-viral gene therapy approach for DMD using PB transposons underscoring their potential to deliver large therapeutic genes.status: publishe

Efficient CRISPR/Cas9-mediated editing of trinucleotide repeat expansion in myotonic dystrophy patient-derived iPS and myogenic cells

International audienceCRISPR/Cas9 is an attractive platform to potentially correct dominant genetic diseases by gene editing with unprecedented precision. In the current proof-of-principle study, we explored the use of CRISPR/Cas9 for gene-editing in myotonic dys-trophy type-1 (DM1), an autosomal-dominant muscle disorder, by excising the CTG-repeat expansion in the 3-untranslated-region (UTR) of the human myotonic dystrophy protein kinase (DMPK) gene in DM1 patient-specific induced pluripotent stem cells (DM1-iPSC), DM1-iPSC-derived myogenic cells and DM1 patient-specific myoblasts. To eliminate the pathogenic gain-of-function mutant DMPK transcript , we designed a dual guide RNA based strategy that excises the CTG-repeat expansion with high efficiency , as confirmed by Southern blot and single molecule real-time (SMRT) sequencing. Correction efficiencies up to 90% could be attained in DM1-iPSC as confirmed at the clonal level, following ribonucle-oprotein (RNP) transfection of CRISPR/Cas9 components without the need for selective enrichment. Expanded CTG repeat excision resulted in the disappearance of ribonuclear foci, a quintessential cellular phenotype of DM1, in the corrected DM1-iPSC, DM1-iPSC-derived myogenic cells and DM1 myoblasts. Consequently, the normal intracellular localization of the muscleblind-like splicing regulator 1 (MBNL1) was restored, resulting in the normalization of splicing pattern of SERCA1. This study validates the use of CRISPR/Cas9 for gene editing of repeat expansions

Hepatocyte-Targeted Expression by Integrase-Defective Lentiviral Vectors Induces Antigen-Specific Tolerance in Mice with Low Genotoxic Risk

Lentiviral vectors are attractive tools for liver-directed gene therapy because of their capacity for stable gene expression and the lack of preexisting immunity in most human subjects. However, the use of integrating vectors may raise some concerns about the potential risk of insertional mutagenesis. Here we investigated liver gene transfer by integrase-defective lentiviral vectors (IDLVs) containing an inactivating mutation in the integrase (D64V). Hepatocyte-targeted expression using IDLVs resulted in the sustained and robust induction of immune tolerance to both intracellular and secreted proteins, despite the reduced transgene expression levels in comparison with their integrase-competent vector counterparts. IDLV-mediated and hepatocyte-targeted coagulation factor IX (FIX) expression prevented the induction of neutralizing antibodies to FIX even after antigen rechallenge in hemophilia B mice and accounted for relatively prolonged therapeutic FIX expression levels. Upon the delivery of intracellular model antigens, hepatocyte-targeted IDLVs induced transgene-specific regulatory T cells that contributed to the observed immune tolerance. Deep sequencing of IDLV-transduced livers showed only rare genomic integrations that had no preference for gene coding regions and occurred mostly by a mechanism inconsistent with residual integrase activity. Conclusion: IDLVs provide an attractive platform for the tolerogenic expression of intracellular or secreted proteins in the liver with a substantially reduced risk of insertional mutagenesis. (hepatology 2011;

Atonal homolog 1 Is a Tumor Suppressor Gene

Colon cancer accounts for more than 10% of all cancer deaths annually. Our genetic evidence from Drosophila and previous in vitro studies of mammalian Atonal homolog 1 (Atoh1, also called Math1 or Hath1) suggest an anti-oncogenic function for the Atonal group of proneural basic helix-loop-helix transcription factors. We asked whether mouse Atoh1 and human ATOH1 act as tumor suppressor genes in vivo. Genetic knockouts in mouse and molecular analyses in the mouse and in human cancer cell lines support a tumor suppressor function for ATOH1. ATOH1 antagonizes tumor formation and growth by regulating proliferation and apoptosis, likely via activation of the Jun N-terminal kinase signaling pathway. Furthermore, colorectal cancer and Merkel cell carcinoma patients show genetic and epigenetic ATOH1 loss-of-function mutations. Our data indicate that ATOH1 may be an early target for oncogenic mutations in tissues where it instructs cellular differentiation

Translating the genomics revolution: the need for an international gene therapy consortium for monogenic diseases

Letter to the Edito