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Find video protocols related to scientific articles indexed in Pubmed.
Manufacturing and characterization of a recombinant adeno-associated virus type 8 reference standard material.
Hum. Gene Ther.
PUBLISHED: 10-03-2014
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Abstract Gene therapy approaches using recombinant adeno-associated virus serotype 2 (rAAV2) and serotype 8 (rAAV8) have achieved significant clinical benefits. The generation of rAAV Reference Standard Materials (RSM) is key to providing points of reference for particle titer, vector genome titer, and infectious titer for gene transfer vectors. Following the example of the rAAV2RSM, here we have generated and characterized a novel RSM based on rAAV serotype 8. The rAAV8RSM was produced using transient transfection, and the purification was based on density gradient ultracentrifugation. The rAAV8RSM was distributed for characterization along with standard assay protocols to 16 laboratories worldwide. Mean titers and 95% confidence intervals were determined for capsid particles (mean, 5.50×10(11) pt/ml; CI, 4.26×10(11) to 6.75×10(11) pt/ml), vector genomes (mean, 5.75×10(11) vg/ml; CI, 3.05×10(11) to 1.09×10(12) vg/ml), and infectious units (mean, 1.26×10(9) IU/ml; CI, 6.46×10(8) to 2.51×10(9) IU/ml). Notably, there was a significant degree of variation between institutions for each assay despite the relatively tight correlation of assay results within an institution. This outcome emphasizes the need to use RSMs to calibrate the titers of rAAV vectors in preclinical and clinical studies at a time when the field is maturing rapidly. The rAAV8RSM has been deposited at the American Type Culture Collection (VR-1816) and is available to the scientific community.
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A Phase 1/2a Follistatin Gene Therapy Trial for Becker Muscular Dystrophy.
Mol. Ther.
PUBLISHED: 08-26-2014
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Becker muscular dystrophy (BMD) is a variant of dystrophin deficiency resulting from DMD gene mutations. Phenotype is variable with loss of ambulation in late teenage or late mid-life years. There is currently no treatment for this condition. In this BMD proof-of-principle clinical trial, a potent myostatin antagonist, follistatin (FS), was used to inhibit the myostatin pathway. Extensive preclinical studies, using adeno-associated virus (AAV) to deliver follistatin, demonstrated an increase in strength. For this trial, we used the alternatively spliced FS344 to avoid potential binding to off target sites. AAV1.CMV.FS344 was delivered to six BMD patients by direct bilateral intramuscular quadriceps injections. Cohort 1 included three subjects receiving 3?×?10(11) vg/kg/leg. The distance walked on the 6MWT was the primary outcome measure. Patients 01 and 02 improved 58 meters (m) and 125 m, respectively. Patient 03 showed no change. In Cohort 2, Patients 05 and 06 received 6?×?10(11) vg/kg/leg with improved 6MWT by 108 m and 29 m, whereas, Patient 04 showed no improvement. No adverse effects were encountered. Histological changes corroborated benefit showing reduced endomysial fibrosis, reduced central nucleation, more normal fiber size distribution with muscle hypertrophy, especially at high dose. The results are encouraging for treatment of dystrophin-deficient muscle diseases.Molecular Therapy (2014); doi:10.1038/mt.2014.200.
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Retinal gene therapy in patients with choroideremia: initial findings from a phase 1/2 clinical trial.
Lancet
PUBLISHED: 01-16-2014
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Choroideremia is an X-linked recessive disease that leads to blindness due to mutations in the CHM gene, which encodes the Rab escort protein 1 (REP1). We assessed the effects of retinal gene therapy with an adeno-associated viral (AAV) vector encoding REP1 (AAV.REP1) in patients with this disease.
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VIP-expressing dendritic cells protect against spontaneous autoimmune peripheral polyneuropathy.
Mol. Ther.
PUBLISHED: 01-15-2014
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The spontaneous autoimmune peripheral polyneuropathy (SAPP) model in B7-2 knockout nonobese diabetic mice mimics a progressive and unremitting course of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). In this study, bone marrow-derived dendritic cells (DCs) were transduced to express vasoactive intestinal polypeptide (VIP) using a lentiviral vector (LV-VIP). These transduced DCs (LV-VIP-DCs) were then injected intravenously (i.v.) into 16-week-old (before disease onset) and 21-week-old (after disease onset) SAPP mice in order to prevent or attenuate the disease. Outcome measures included behavioral tests, clinical and histological scoring, electrophysiology, real-time PCR, flow cytometry analyses, and enzyme-linked immunosorbent assay. LV-VIP-DCs were recruited to the inflamed sciatic nerve and reduced the expression of inflammatory cytokines. A single injection of LV-VIP-DC delayed the onset of disease, stabilized, and attenuated clinical signs correlating with ameliorated behavioral functions, reduced nerve demyelination, and improved nerve conduction. This proof-of-principle study is an important step potentially leading to a clinical translational study using DCs expressing VIP in cases of CIDP refractory to standard immunosuppressive therapy.
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Vascular delivery of rAAVrh74.MCK.GALGT2 to the gastrocnemius muscle of the rhesus macaque stimulates the expression of dystrophin and laminin ?2 surrogates.
Mol. Ther.
PUBLISHED: 09-18-2013
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Overexpression of GALGT2 in skeletal muscle can stimulate the glycosylation of ? dystroglycan and the upregulation of normally synaptic dystroglycan-binding proteins, some of which are dystrophin and laminin ?2 surrogates known to be therapeutic in forms of muscular dystrophy. Here, we describe for the first time vascular delivery of GALGT2 gene therapy in a large animal model, the rhesus macaque. Recombinant adeno associated virus, rhesus serotype 74 (rAAVrh74), was used to deliver GALGT2 via the femoral artery to the gastrocnemius muscle using an isolated focal limb perfusion method. GALGT2 expression averaged 44±4% of myofibers after treatment in macaques with low pre-existing anti-rAAVrh74 serum antibodies, and expression was reduced to 9±4% of myofibers in macaques with high pre-existing rAAVrh74 immunity (p<0.001, n=12 per group). This was the case regardless of the addition of immunosuppressants, including prednisolone, tacrolimus and mycophenolate mofetil. GALGT2-treated macaque muscles showed increased glycosylation of ? dystroglycan and increased expression of dystrophin and laminin ?2 surrogate proteins, including utrophin, plectin1, agrin and laminin ?5. These experiments demonstrate successful transduction of rhesus macaque muscle with rAAVrh74.MCK.GALGT2 after vascular delivery and induction of molecular changes thought to be therapeutic in several forms of muscular dystrophy.Molecular Therapy (2013); doi:10.1038/mt.2013.246.
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Micro-dystrophin and follistatin co-delivery restores muscle function in aged DMD model.
Hum. Mol. Genet.
PUBLISHED: 07-17-2013
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Pharmacologic strategies have provided modest improvement in the devastating muscle-wasting disease, Duchenne muscular dystrophy (DMD). Pre-clinical gene therapy studies have shown promise in the mdx mouse model; however, studies conducted after disease onset fall short of fully correcting muscle strength or protecting against contraction-induced injury. Here we examine the treatment effect on muscle physiology in aged dystrophic mice with significant disease pathology by combining two promising therapies: micro-dystrophin gene replacement and muscle enhancement with follistatin, a potent myostatin inhibitor. Individual treatments with micro-dystrophin and follistatin demonstrated marked improvement in mdx mice but were insufficient to fully restore muscle strength and response to injury to wild-type levels. Strikingly, when combined, micro-dystrophin/follistatin treatment restored force generation and conferred resistance to contraction-induced injury in aged mdx mice. Pre-clinical studies with miniature dystrophins have failed to demonstrate full correction of the physiological defects seen in mdx mice. Importantly, the addition of a muscle enhancement strategy with delivery of follistatin in combination with micro-dystrophin gene therapy completely restored resistance to eccentric contraction-induced injury and improved force. Eccentric contraction-induced injury is a pre-clinical parameter relevant to the exercise induced injury that occurs in DMD patients, and herein, we demonstrate compelling evidence for the therapeutic potential of micro-dystrophin/follistatin combinatorial therapy.
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AAV1.NT-3 Gene Therapy for Charcot-Marie-Tooth Neuropathy.
Mol. Ther.
PUBLISHED: 06-12-2013
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Charcot-Marie-Tooth (CMT) neuropathies represent a heterogeneous group of peripheral nerve disorders affecting 1 in 2,500 persons. One variant, CMT1A, is a primary Schwann cell (SC) disorder, and represents the single most common variant. In previous studies, we showed that neurotrophin-3 (NT-3) improved the trembler(J) (Tr(J)) mouse and also showed efficacy in CMT1A patients. Long-term treatment with NT-3 was not possible related to its short half-life and lack of availability. This led to considerations of NT-3 gene therapy via adenoassociated virus (AAV) delivery to muscle, acting as secretory organ for widespread distribution of this neurotrophic agent. In the Tr(J) model of demyelinating CMT, rAAV1.NT-3 therapy resulted in measurable NT-3 secretion levels in blood sufficient to provide improvement in motor function, histopathology, and electrophysiology of peripheral nerves. Furthermore, we showed that the compound muscle action potential amplitude can be used as surrogate for functional improvement and established the therapeutic dose and a preferential muscle-specific promoter to achieve sustained NT-3 levels. These studies of intramuscular (i.m.) delivery of rAAV1.NT-3 serve as a template for future CMT1A clinical trials with a potential to extend treatment to other nerve diseases with impaired nerve regeneration.Molecular Therapy (2013); doi:10.1038/mt.2013.250.
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Dose-dependent Toxicity of Humanized Renilla reniformis GFP (hrGFP) Limits Its Utility as a Reporter Gene in Mouse Muscle.
Mol Ther Nucleic Acids
PUBLISHED: 04-18-2013
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Gene therapy has historically focused on delivering protein-coding genes to target cells or tissues using a variety of vectors. In recent years, the field has expanded to include gene-silencing strategies involving delivery of noncoding inhibitory RNAs, such as short hairpin RNAs or microRNAs (miRNAs). Often called RNA interference (RNAi) triggers, these small inhibitory RNAs are difficult or impossible to visualize in living cells or tissues. To circumvent this detection problem and ensure efficient delivery in preclinical studies, vectors can be engineered to coexpress a fluorescent reporter gene to serve as a marker of transduction. In this study, we set out to optimize adeno-associated viral (AAV) vectors capable of delivering engineered miRNAs and green fluorescent protein (GFP) reporter genes to skeletal muscle. Although the more broadly utilized enhanced GFP (eGFP) gene derived from the jellyfish, Aequorea victoria was a conventional choice, we were concerned about some previous studies suggesting this protein was myotoxic. We thus opted to test vectors carrying the humanized Renilla reniformis-derived GFP (hrGFP) gene, which has not seen as extensive usage as eGFP but was purported to be a safer and less cytotoxic alternative. Employing AAV6 vector dosages typically used in preclinical gene transfer studies (3×10(10) -1 × 10(11) particles), we found that hrGFP caused dose-dependent myopathy when delivered to wild-type (wt) mouse muscle, whereas identical titers of AAV6 carrying eGFP were relatively benign. Dose de-escalation at or below 8 × 10(9) AAV particles effectively reduced or eliminated hrGFP-associated myotoxicity, but also had dampening effects on green fluorescence and miRNA-mediated gene silencing in whole muscles. We conclude that hrGFP is impractical for use as a transduction marker in preclinical, AAV-based RNA interference therapy studies where adult mouse muscle is the target organ. Moreover, our data support that eGFP is superior to hrGFP as a reporter gene in mouse muscle. These results may impact the design of future preclinical gene therapy studies targeting muscles and non-muscle tissues alike.Molecular Therapy - Nucleic Acids (2013) 2, e86; doi:10.1038/mtna.2013.16; published online 16 April 2013.
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Impaired regeneration in LGMD2A supported by increased PAX7-positive satellite cell content and muscle-specific microrna dysregulation.
Muscle Nerve
PUBLISHED: 03-29-2013
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Recent in vitro studies suggest that CAPN3 deficiency leads initially to accelerated myofiber formation followed by depletion of satellite cells (SC). In normal muscle, up-regulation of miR-1 and miR-206 facilitates transition from proliferating SCs to differentiating myogenic progenitors.
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AAV-mediated overexpression of human ?7 integrin leads to histological and functional improvement in dystrophic mice.
Mol. Ther.
PUBLISHED: 01-15-2013
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Duchenne muscular dystrophy (DMD) is a severe muscle disease caused by mutations in the DMD gene, with loss of its gene product, dystrophin. Dystrophin helps link integral membrane proteins to the actin cytoskeleton and stabilizes the sarcolemma during muscle activity. We investigated an alternative therapeutic approach to dystrophin replacement by overexpressing human ?7 integrin (ITGA7) using adeno-associated virus (AAV) delivery. ITGA7 is a laminin receptor in skeletal and cardiac muscle that links the extracellular matrix (ECM) to the actin skeleton. It is modestly upregulated in DMD muscle and has been proposed to be an important modifier of dystrophic symptoms. We delivered rAAV8.MCK.ITGA7 to the lower limb of mdx mice through isolated limb perfusion (ILP) of the femoral artery. We demonstrated ~50% of fibers in the tibialis anterior (TA) and extensor digitorum longus (EDL) overexpressing ?7 integrin at the sarcolemma following AAV gene transfer. The increase in ITGA7 in skeletal muscle significantly protected against loss of force following eccentric contraction-induced injury compared with untreated (contralateral) muscles while specific force following tetanic contraction was unchanged. Reversal of additional dystrophic features included reduced Evans blue dye (EBD) uptake and increased muscle fiber diameter. Taken together, this data shows that rAAV8.MCK.ITGA7 gene transfer stabilizes the sarcolemma potentially preserving mdx muscle from further damage. This therapeutic approach demonstrates promise as a viable treatment for DMD with further implications for other forms of muscular dystrophy.
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Evaluation of the fate of rAAV genomes following in vivo administration.
Methods Mol. Biol.
PUBLISHED: 10-29-2011
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Recombinant adeno-associated virus (rAAV) vectors are capable of mediating long-term gene expression in a wide variety of animals, including primates. The rAAV genome is packaged into the virion as single-stranded DNA devoid of any viral genes. A proportion of the single-stranded genomes are converted into transcriptionally active double-stranded DNA (dsDNA) early after nuclear entry by second-strand synthesis mediated by host repair DNA polymerases or/and by annealing of the rAAV (-) and (+) strands. Second-generation, self-complementary vectors are packaged as single-strand hairpins and rapidly assume a dsDNA conformation independent of the action of polymerases. In both cases, linear dsDNA vector genomes circularize and can undergo concatemerization into higher order forms (McCarty et al. Annu Rev Genet 38: 819-845, 2004; Schultz and Chamberlain Mol Ther 16: 1189-1199, 2008; Duan et al. J Virol 72: 8568-8577, 1998). As a result, rAAV vector genomes are maintained mainly as circular monomeric and concatemeric episomal forms in skeletal muscle and liver (Schnepp et al. J Virol 77: 3495-3504, 2003; Penaud-Budloo et al. J Virol 82: 7875-7885, 2008; Nakai et al. J Virol 75: 6969-6976, 2001). Moreover, in nonhuman primate skeletal muscle, it has been shown that rAAV episomes assimilate into chromatin with a typical nucleosomal pattern that presumably is important for persistence and gene expression in quiescent tissues over a period of several years (Penaud-Budloo et al. J Virol 82: 7875-7885, 2008). Conversely, although rAAV is not considered as an integrative vector per se, introduction of exogenous DNA into the nuclear compartment can result in low-level vector assimilation into the host genome. One mechanism appears to involve vector insertion at sites of double-strand DNA breaks using cellular DNA repair enzymes. As rAAV gene transfer technology and applications mature, a better characterization of the genetic fate of the rAAV genome is critical to accurately evaluate the risk/benefit ratio for a particular disease indication. In this chapter, two complementary methods are detailed to enable characterization of rAAV molecular structure in a particular target tissue and estimation of its integration frequency.
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Rapid and efficient clearance of blood-borne virus by liver sinusoidal endothelium.
PLoS Pathog.
PUBLISHED: 06-02-2011
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The liver removes quickly the great bulk of virus circulating in blood, leaving only a small fraction to infect the host, in a manner characteristic of each virus. The scavenger cells of the liver sinusoids are implicated, but the mechanism is entirely unknown. Here we show, borrowing a mouse model of adenovirus clearance, that nearly all infused adenovirus is cleared by the liver sinusoidal endothelial cell (LSEC). Using refined immunofluorescence microscopy techniques for distinguishing macrophages and endothelial cells in fixed liver, and identifying virus by two distinct physicochemical methods, we localized adenovirus 1 minute after infusion mainly to the LSEC (?90%), finding ?10% with Kupffer cells (KC) and none with hepatocytes. Electron microscopy confirmed our results. In contrast with much prior work claiming the main scavenger to be the KC, our results locate the clearance mechanism to the LSEC and identify this cell as a key site of antiviral activity.
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Sustained alpha-sarcoglycan gene expression after gene transfer in limb-girdle muscular dystrophy, type 2D.
Ann. Neurol.
PUBLISHED: 10-30-2010
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The aim of this study was to attain long-lasting alpha-sarcoglycan gene expression in limb-girdle muscular dystrophy, type 2D (LGMD2D) subjects mediated by adeno-associated virus (AAV) gene transfer under control of a muscle specific promoter (tMCK).
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Dystrophin immunity in Duchennes muscular dystrophy.
N. Engl. J. Med.
PUBLISHED: 10-08-2010
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We report on delivery of a functional dystrophin transgene to skeletal muscle in six patients with Duchennes muscular dystrophy. Dystrophin-specific T cells were detected after treatment, providing evidence of transgene expression even when the functional protein was not visualized in skeletal muscle. Circulating dystrophin-specific T cells were unexpectedly detected in two patients before vector treatment. Revertant dystrophin fibers, which expressed functional, truncated dystrophin from the deleted endogenous gene after spontaneous in-frame splicing, contained epitopes targeted by the autoreactive T cells. The potential for T-cell immunity to self and nonself dystrophin epitopes should be considered in designing and monitoring experimental therapies for this disease. (Funded by the Muscular Dystrophy Association and others; ClinicalTrials.gov number, NCT00428935.).
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Characterization of a recombinant adeno-associated virus type 2 Reference Standard Material.
Hum. Gene Ther.
PUBLISHED: 09-16-2010
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A recombinant adeno-associated virus serotype 2 Reference Standard Material (rAAV2 RSM) has been produced and characterized with the purpose of providing a reference standard for particle titer, vector genome titer, and infectious titer for AAV2 gene transfer vectors. Production and purification of the reference material were carried out by helper virus-free transient transfection and chromatographic purification. The purified bulk material was vialed, confirmed negative for microbial contamination, and then distributed for characterization along with standard assay protocols and assay reagents to 16 laboratories worldwide. Using statistical transformation and modeling of the raw data, mean titers and confidence intervals were determined for capsid particles ({X}, 9.18?x?10¹¹ particles/ml; 95% confidence interval [CI], 7.89?x?10¹¹ to 1.05?x?10¹² particles/ml), vector genomes ({X}, 3.28?x?10¹? vector genomes/ml; 95% CI, 2.70?x?10¹? to 4.75?x?10¹? vector genomes/ml), transducing units ({X}, 5.09?x?10? transducing units/ml; 95% CI, 2.00?x?10? to 9.60?x?10? transducing units/ml), and infectious units ({X}, 4.37?x?10? TCID?? IU/ml; 95% CI, 2.06?x?10? to 9.26?x?10? TCID?? IU/ml). Further analysis confirmed the identity of the reference material as AAV2 and the purity relative to nonvector proteins as greater than 94%. One obvious trend in the quantitative data was the degree of variation between institutions for each assay despite the relatively tight correlation of assay results within an institution. This relatively poor degree of interlaboratory precision and accuracy was apparent even though attempts were made to standardize the assays by providing detailed protocols and common reagents. This is the first time that such variation between laboratories has been thoroughly documented and the findings emphasize the need in the field for universal reference standards. The rAAV2 RSM has been deposited with the American Type Culture Collection and is available to the scientific community to calibrate laboratory-specific internal titer standards. Anticipated uses of the rAAV2 RSM are discussed.
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The association of BMI and Braden total score on the occurrence of pressure ulcers.
J Wound Ostomy Continence Nurs
PUBLISHED: 07-21-2010
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We compared pressure ulcer (PU) prevalence patients with a body mass index (BMI) of 40 or more, and Braden Scale scores of 16 or more to patients with lower BMI.
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Persistent expression of FLAG-tagged micro dystrophin in nonhuman primates following intramuscular and vascular delivery.
Mol. Ther.
PUBLISHED: 11-10-2009
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Animal models for Duchenne muscular dystrophy (DMD) have species limitations related to assessing function, immune response, and distribution of micro- or mini-dystrophins. Nonhuman primates (NHPs) provide the ideal model to optimize vector delivery across a vascular barrier and provide accurate dose estimates for widespread transduction. To address vascular delivery and dosing in rhesus macaques, we have generated a fusion construct that encodes an eight amino-acid FLAG epitope at the C-terminus of micro-dystrophin to facilitate translational studies targeting DMD. Intramuscular (IM) injection of AAV8.MCK.micro-dys.FLAG in the tibialis anterior (TA) of macaques demonstrated robust gene expression, with muscle transduction (50-79%) persisting for up to 5 months. Success by IM injection was followed by targeted vascular delivery studies using a fluoroscopy-guided catheter threaded through the femoral artery. Three months after gene transfer, >80% of muscle fibers showed gene expression in the targeted muscle. No cellular immune response to AAV8 capsid, micro-dystrophin, or the FLAG tag was detected by interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot (ELISpot) at any time point with either route. In summary, an epitope-tagged micro-dystrophin cassette enhances the ability to evaluate site-specific localization and distribution of gene expression in the NHP in preparation for vascular delivery clinical trials.
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Limb-girdle muscular dystrophy type 2D gene therapy restores alpha-sarcoglycan and associated proteins.
Ann. Neurol.
PUBLISHED: 10-03-2009
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alpha-Sarcoglycan deficiency results in a severe form of muscular dystrophy (limb-girdle muscular dystrophy type 2D [LGMD2D]) without treatment. Gene replacement represents a strategy for correcting the underlying defect. Questions related to this approach were addressed in this clinical trial, particularly the need for immunotherapy and persistence of gene expression.
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Crystal structure of a 3B3 variant--a broadly neutralizing HIV-1 scFv antibody.
Protein Sci.
PUBLISHED: 09-29-2009
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We present the crystal structure determination of an anti-HIV-1 gp120 single-chain variable fragment antibody variant, 3B3, at 2.5 A resolution. This 3B3 variant was derived from the b12 antibody, using phage display and site-directed mutagenesis of the variable heavy chain (V(H)) complementary-determining regions (CDRs). 3B3 exhibits enhanced binding affinity and neutralization activity against several cross-clade primary isolates of HIV-1 by interaction with the recessed CD4-binding site on the gp120 envelope protein. Comparison with the structures of the unbound and bound forms of b12, the 3B3 structure closely resembles these structures with minimal differences with two notable exceptions. First, there is a reorientation of the CDR-H3 of the V(H) domain where the primary sequences evolved from b12 to 3B3. The structural changes in CDR-H3 of 3B3, in light of the b12-gp120 complex structure, allow for positioning an additional Trp side chain in the binding interface with gp120. Finally, the second region of structural change involves two peptide bond flips in CDR-L3 of the variable light (V(L)) domain triggered by a point mutation in CDR-H3 of Q100eY resulting in changes in the intramolecular hydrogen bonding patterning between the V(L) and V(H) domains. Thus, the enhanced binding affinities and neutralization capabilities of 3B3 relative to b12 probably result from higher hydrophobic driving potential by burying more aromatic residues at the 3B3-gp120 interface and by indirect stabilization of intramolecular contacts of the core framework residues between the V(L) and V(H) domains possibly through more favorable entropic effect through the expulsion of water.
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Follistatin gene delivery enhances muscle growth and strength in nonhuman primates.
Sci Transl Med
PUBLISHED: 08-04-2009
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Antagonists of myostatin, a blood-borne negative regulator of muscle growth produced in muscle cells, have shown considerable promise for enhancing muscle mass and strength in rodent studies and could serve as potential therapeutic agents for human muscle diseases. One of the most potent of these agents, follistatin, is both safe and effective in mice, but similar tests have not been performed in nonhuman primates. To assess this important criterion for clinical translation, we tested an alternatively spliced form of human follistatin that affects skeletal muscle but that has only minimal effects on nonmuscle cells. When injected into the quadriceps of cynomolgus macaque monkeys, a follistatin isoform expressed from an adeno-associated virus serotype 1 vector, AAV1-FS344, induced pronounced and durable increases in muscle size and strength. Long-term expression of the transgene did not produce any abnormal changes in the morphology or function of key organs, indicating the safety of gene delivery by intramuscular injection of an AAV1 vector. Our results, together with the findings in mice, suggest that therapy with AAV1-FS344 may improve muscle mass and function in patients with certain degenerative muscle disorders.
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Overexpression of Galgt2 in skeletal muscle prevents injury resulting from eccentric contractions in both mdx and wild-type mice.
Am. J. Physiol., Cell Physiol.
PUBLISHED: 04-28-2009
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The cytotoxic T cell (CT) GalNAc transferase, or Galgt2, is a UDP-GalNAc:beta1,4-N-acetylgalactosaminyltransferase that is localized to the neuromuscular synapse in adult skeletal muscle, where it creates the synaptic CT carbohydrate antigen {GalNAcbeta1,4[NeuAc(orGc)alpha2, 3]Galbeta1,4GlcNAcbeta-}. Overexpression of Galgt2 in the skeletal muscles of transgenic mice inhibits the development of muscular dystrophy in mdx mice, a model for Duchenne muscular dystrophy. Here, we provide physiological evidence as to how Galgt2 may inhibit the development of muscle pathology in mdx animals. Both Galgt2 transgenic wild-type and mdx skeletal muscles showed a marked improvement in normalized isometric force during repetitive eccentric contractions relative to nontransgenic littermates, even using a paradigm where nontransgenic muscles had force reductions of 95% or more. Muscles from Galgt2 transgenic mice, however, showed a significant decrement in normalized specific force and in hindlimb and forelimb grip strength at some ages. Overexpression of Galgt2 in muscles of young adult mdx mice, where Galgt2 has no effect on muscle size, also caused a significant decrease in force drop during eccentric contractions and increased normalized specific force. A comparison of Galgt2 and microdystrophin overexpression using a therapeutically relevant intravascular gene delivery protocol showed Galgt2 was as effective as microdystrophin at preventing loss of force during eccentric contractions. These experiments provide a mechanism to explain why Galgt2 overexpression inhibits muscular dystrophy in mdx muscles. That overexpression also prevents loss of force in nondystrophic muscles suggests that Galgt2 is a therapeutic target with broad potential applications.
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Infectious molecular clones of adeno-associated virus isolated directly from human tissues.
J. Virol.
PUBLISHED: 02-13-2009
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Adeno-associated virus (AAV) replication and biology have been extensively studied using cell culture systems, but there is precious little known about AAV biology in natural hosts. As part of our ongoing interest in the in vivo biology of AAV, we previously described the existence of extrachromosomal proviral AAV genomes in human tissues. In the current work, we describe the molecular structure of infectious DNA clones derived directly from these tissues. Sequence-specific linear rolling-circle amplification was utilized to isolate clones of native circular AAV DNA. Several molecular clones containing unit-length viral genomes directed the production of infectious wild-type AAV upon DNA transfection in the presence of adenovirus help. DNA sequence analysis of the molecular clones revealed the ubiquitous presence of a double-D inverted terminal repeat (ITR) structure, which implied a mechanism by which the virus is able to maintain ITR sequence continuity and persist in the absence of host chromosome integration. These data suggest that the natural life cycle of AAV, unlike that of retroviruses, might not have genome integration as an obligatory component.
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Therapeutic microRNA delivery suppresses tumorigenesis in a murine liver cancer model.
Cell
PUBLISHED: 02-11-2009
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Therapeutic strategies based on modulation of microRNA (miRNA) activity hold great promise due to the ability of these small RNAs to potently influence cellular behavior. In this study, we investigated the efficacy of a miRNA replacement therapy for liver cancer. We demonstrate that hepatocellular carcinoma (HCC) cells exhibit reduced expression of miR-26a, a miRNA that is normally expressed at high levels in diverse tissues. Expression of this miRNA in liver cancer cells in vitro induces cell-cycle arrest associated with direct targeting of cyclins D2 and E2. Systemic administration of this miRNA in a mouse model of HCC using adeno-associated virus (AAV) results in inhibition of cancer cell proliferation, induction of tumor-specific apoptosis, and dramatic protection from disease progression without toxicity. These findings suggest that delivery of miRNAs that are highly expressed and therefore tolerated in normal tissues but lost in disease cells may provide a general strategy for miRNA replacement therapies.
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Vector-mediated gene transfer engenders long-lived neutralizing activity and protection against SIV infection in monkeys.
Nat. Med.
PUBLISHED: 02-10-2009
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The key to an effective HIV vaccine is development of an immunogen that elicits persisting antibodies with broad neutralizing activity against field strains of the virus. Unfortunately, very little progress has been made in finding or designing such immunogens. Using the simian immunodeficiency virus (SIV) model, we have taken a markedly different approach: delivery to muscle of an adeno-associated virus gene transfer vector expressing antibodies or antibody-like immunoadhesins having predetermined SIV specificity. With this approach, SIV-specific molecules are endogenously synthesized in myofibers and passively distributed to the circulatory system. Using such an approach in monkeys, we have now generated long-lasting neutralizing activity in serum and have observed complete protection against intravenous challenge with virulent SIV. In essence, this strategy bypasses the adaptive immune system and holds considerable promise as a unique approach to an effective HIV vaccine.
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Essential metabolic, anti-inflammatory, and anti-tumorigenic functions of miR-122 in liver.
J. Clin. Invest.
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miR-122, an abundant liver-specific microRNA (miRNA), regulates cholesterol metabolism and promotes hepatitis C virus (HCV) replication. Reduced miR-122 expression in hepatocellular carcinoma (HCC) correlates with metastasis and poor prognosis. Nevertheless, the consequences of sustained loss of function of miR-122 in vivo have not been determined. Here, we demonstrate that deletion of mouse Mir122 resulted in hepatosteatosis, hepatitis, and the development of tumors resembling HCC. These pathologic manifestations were associated with hyperactivity of oncogenic pathways and hepatic infiltration of inflammatory cells that produce pro-tumorigenic cytokines, including IL-6 and TNF. Moreover, delivery of miR-122 to a MYC-driven mouse model of HCC strongly inhibited tumorigenesis, further supporting the tumor suppressor activity of this miRNA. These findings reveal critical functions for miR-122 in the maintenance of liver homeostasis and have important therapeutic implications, including the potential utility of miR-122 delivery for selected patients with HCC and the need for careful monitoring of patients receiving miR-122 inhibition therapy for HCV.
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Homologous recombination mediates functional recovery of dysferlin deficiency following AAV5 gene transfer.
PLoS ONE
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The dysferlinopathies comprise a group of untreatable muscle disorders including limb girdle muscular dystrophy type 2B, Miyoshi myopathy, distal anterior compartment syndrome, and rigid spine syndrome. As with other forms of muscular dystrophy, adeno-associated virus (AAV) gene transfer is a particularly auspicious treatment strategy, however the size of the DYSF cDNA (6.5 kb) negates packaging into traditional AAV serotypes known to express well in muscle (i.e. rAAV1, 2, 6, 8, 9). Potential advantages of a full cDNA versus a mini-gene include: maintaining structural-functional protein domains, evading protein misfolding, and avoiding novel epitopes that could be immunogenic. AAV5 has demonstrated unique plasticity with regards to packaging capacity and recombination of virions containing homologous regions of cDNA inserts has been implicated in the generation of full-length transcripts. Herein we show for the first time in vivo that homologous recombination following AAV5.DYSF gene transfer leads to the production of full length transcript and protein. Moreover, gene transfer of full-length dysferlin protein in dysferlin deficient mice resulted in expression levels sufficient to correct functional deficits in the diaphragm and importantly in skeletal muscle membrane repair. Intravascular regional gene transfer through the femoral artery produced high levels of transduction and enabled targeting of specific muscle groups affected by the dysferlinopathies setting the stage for potential translation to clinical trials. We provide proof of principle that AAV5 mediated delivery of dysferlin is a highly promising strategy for treatment of dysferlinopathies and has far-reaching implications for the therapeutic delivery of other large genes.
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Gene therapy for muscular dystrophy: lessons learned and path forward.
Neurosci. Lett.
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Our Translational Gene Therapy Center has used small molecules for exon skipping and mutation suppression and gene transfer to replace or provide surrogate genes as tools for molecular-based approaches for the treatment of muscular dystrophies. Exon skipping is targeted at the pre-mRNA level allowing one or more exons to be omitted to restore the reading frame. In Duchenne Muscular Dystrophy (DMD), clinical trials have been performed with two different oligomers, a 2O-methyl-ribo-oligonucleoside-phosphorothioate (2OMe) and a phosphorodiamidate morpholino (PMO). Both have demonstrated early evidence of efficacy. A second molecular approach involves suppression of stop codons to promote readthrough of the DMD gene. We have been able to establish proof of principle for mutation suppression using the aminoglycoside, gentamicin. A safer, orally administered, alternative agent referred to as Ataluren (PTC124) has been used in clinical trials and is currently under consideration for approval by the FDA. Using a gene therapy approach, we have completed two trials and have initiated a third. For DMD, we used a mini-dystrophin transferred in adeno-associated virus (AAV). In this trial an immune response was seen directed against transgene product, a quite unexpected outcome that will help guide further studies. For limb girdle muscular dystrophy 2D (alpha-sarcoglycan deficiency), the transgene was again transferred using AAV but in this study, a muscle specific creatine kinase promoter controlled gene expression that persisted for six months. A third gene therapy trial has been initiated with transfer of the follistatin gene in AAV directly to the quadriceps muscle. Two diseases with selective quadriceps muscle weakness are undergoing gene transfer including sporadic inclusion body myositis (sIBM) and Becker muscular dystrophy (BMD). Increasing the size and strength of the muscle is the goal of this study. Most importantly, no adverse events have been encountered in any of these clinical trials.
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Knee extensor strength exhibits potential to predict function in sporadic inclusion-body myositis.
Muscle Nerve
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In this study we address the challenging issue of potential use of muscle strength to predict function in clinical trials. This has immediate relevance to translational studies that attempt to improve quadriceps strength in sporadic inclusion-body myositis (sIBM).
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.