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Niemann-Pick disease type A (NPD-A) is a lysosomal storage disorder characterized by neurodegeneration and early death. It is caused by loss-of-function mutations in the gene encoding for acid sphingomyelinase (ASM), which hydrolyzes sphingomyelin into ceramide. Here, we evaluated the safety of cerebellomedullary (CM) cistern injection of adeno-associated viral vector serotype 9 encoding human ASM (AAV9-hASM) in nonhuman primates (NHP). We also evaluated its therapeutic benefit in a mouse model of the disease (ASM-KO mice). We found that CM injection in NHP resulted in widespread transgene expression within brain and spinal cord cells without signs of toxicity. CM injection in the ASM-KO mouse model resulted in hASM expression in cerebrospinal fluid and in different brain areas without triggering an inflammatory response. In contrast, direct cerebellar injection of AAV9-hASM triggered immune response. We also identified a minimally effective therapeutic dose for CM injection of AAV9-hASM in mice. Two months after administration, the treatment prevented motor and memory impairment, sphingomyelin (SM) accumulation, lysosomal enlargement, and neuronal death in ASM-KO mice. ASM activity was also detected in plasma from AAV9-hASM CM-injected ASM-KO mice, along with reduced SM amount and decreased inflammation in the liver. Our results support CM injection for future AAV9-based clinical trials in NPD-A as well as other lysosomal storage brain disorders.

Classic galactosemia (CG) is a rare disorder of autosomal recessive inheritance. It is caused predominantly by point mutations as well as deletions in the gene encoding the enzyme galactose‐1‐phosphate uridyltransferase (GALT). The majority of the more than 350 mutations identified in the GALT gene cause a significant reduction in GALT enzyme activity resulting in the toxic buildup of galactose metabolites that in turn is associated with cellular stress and injury. Consequently, developing a therapeutic strategy that reverses both the oxidative and ER stress in CG cells may be helpful in combating this disease. Recombinant adeno‐associated virus (AAV)‐mediated gene therapy to restore GALT activity offers the potential to address the unmet medical needs of galactosemia patients. Here, utilizing fibroblasts derived from CG patients we demonstrated that AAV‐mediated augmentation of GALT protein and activity resulted in the prevention of ER and oxidative stress. We also demonstrate that these CG patient fibroblasts exhibit reduced CD109 and TGFβRII protein levels and that these effectors of cellular homeostasis could be restored following AAV‐mediated expression of GALT. Finally, we show initial in vivo proof‐of‐concept restoration of galactose metabolism in a GALT knockout mouse model following treatment with AAV‐GALT. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined the effect of nebulisation of non-viral cystic fibrosis transmembrane conductance regulator (CFTR) gene therapy on patients with cystic fibrosis.

Background The nuclear membrane of differentiated airway epithelial cells is a significant barrier for nonviral vectors. Trans-cyclohexane-1,2-diol (TCHD) is an amphipathic alcohol that has been shown to collapse nuclear pore cores and allow the uptake of macromolecules that would otherwise be too large for nuclear entry. Previous studies have shown that TCHD can increase lipid-mediated transfection in vitro. Methods We aimed to reproduce these in vitro studies using the cationic lipid GL67A, which we are currently assessing in cystic fibrosis trials and, more importantly, we assessed the effects of TCHD on transfection efficiency in differentiated airway epithelium ex vivo and in mouse lung in vivo using three different drug delivery protocols (nebulisation and bolus administration of TCHD to the mouse lung, as well as perfusion of TCHD to the nasal epithelium, which prolongs contact time between the airway epithelium and drug). Results TCHD (0.5-2%) dose-dependently increased Lipofectamine 2000 and GL67A-mediated transfection of 293T cells by up to 2 logs. Encouragingly, exposure to 8% TCHD (but not 0.5% or 2.0%) increased gene expression in fully differentiated human air liquid interface cultures by approximately 20-fold, although this was accompanied by significant cell damage. However, none of the TCHD treated mice in any of the three protocols had higher gene expression compared to no TCHD controls. Conclusions Although TCHD significantly increases gene transfer in cell lines and differentiated airway epithelium ex vivo, this effect is lost in vivo and further highlights that promising in vitro findings often cannot be translated into in vivo applications. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Spinal muscular atrophy (SMA) is a neuromuscular disease caused by a deficiency of functional SMN protein because of mutations in SMN1. A decrease in SMN activity results in motor neuron cell loss in the spinal cord, leading to a weakness of the proximal muscles responsible for crawling, walking, head/neck control and swallowing as well as the involuntary muscles that control breathing and coughing. Thus, patients present with pulmonary manifestations, paralysis and a shortened lifespan. Gene therapy is emerging as a promising therapeutic strategy for SMA given that the molecular basis for this monogenic disorder is well established. Recent advances and findings from preclinical studies in animal models provide optimism that gene therapy might be an effective therapeutic strategy for treating SMA. [ABSTRACT FROM AUTHOR]

Niemann-Pick type A disease is a lysosomal storage disorder caused by a deficiency in acid sphingomyelinase (ASM) activity. Previously we showed that storage pathology in the ASM knock-out (ASMKO) mouse brain can be corrected by adeno-associated virus serotype 2 (AAV2)-mediated gene transfer. The present experiment compared the relative therapeutic efficacy of different recombinant AAV serotype vectors (1, 2, 5, 7, and 8) using histological, biochemical, and behavioral endpoints. In addition, we evaluated the use of the deep cerebellar nuclei (DCN) as a site for injection to facilitate global distribution of the viral vector and enzyme. Seven-week-old ASM knockout mice were injected within the DCN with different AAV serotype vectors encoding human ASM (hASM) and then killed at either 14 or 20 weeks of age. Results showed that AAV1 was superior to serotypes 2, 5, 7, and 8 in its relative ability to express hASM, alleviate storage accumulation, and correct behavioral deficits. Expression of hASM was found not only within the DCN, but also throughout the cerebellum, brain-stem, midbrain, and spinal cord. This finding demonstrates that targeting the DCN is an effective approach for achieving wide-spread enzyme distribution throughout the CNS. Our results support the continued development of AAV based vectors for gene therapy of the CNS manifestations in Niemann-Pick type A disease. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to examine the effects of adenovirus-mediated expression of p35, a baculovirus gene, on apoptosis induced by hypoxia/reoxygenation (H/R) in cardiomyocytes. Methods: Neonatal rat cardiomyocytes were infected with recombinant adenoviral vectors expressing p35 (Ad2/CMVp35) or no transgene (Ad2/CMVEV) and were then subjected to H/R. Separate groups of non-infected cardiomyocytes were treated with pharmacological caspase inhibitors or antioxidants. Cell viability, apoptosis, caspase activity, and cellular reactive oxygen species (ROS) were measured using various assays. Results: H/R decreased cell viability and increased cellular ROS levels, caspase activity, and cell apoptosis. Infection with Ad2/CMVp35 effectively inhibited the increase in cellular ROS levels, the activities of caspases 3 and 8, apoptosis, and cell death following H/R, whereas Ad2/CMVEV had no effect. Despite its ability to abolish the increase in caspase activity and partially inhibit apoptosis, the pan-caspase inhibitor ZVAD-fmk (100 μM) failed to significantly reduce cell death induced by H/R. N-acetyl-l-cysteine, an antioxidant, completely inhibited H/R-induced increase in cellular ROS levels, but reduced apoptosis and cell death by 30% only. Conclusions: Adenovirus-mediated expression of p35 effectively inhibits H/R-induced cardiomyocyte apoptosis by reducing cellular ROS levels and inhibiting caspase activity. [Copyright &y& Elsevier]

Objective: This study aimed to determine the mode of action of Fas ligand (FasL)/Fas at mediating apoptosis so as to evaluate the potential of FasL in gene therapy for restenosis. Methods: Passaged human coronary artery smooth muscle (HCASM) cells were infected with recombinant adenoviral vectors expressing murine FasL. Various parameters of FasL expression and apoptosis were measured using FACS, immunofluorescence, calorimetric, and cytotoxicity assays. Results: Most HCASM cells under normal growth conditions expressed Fas and were shown to be susceptible to membrane bound but not soluble FasL. However, some FasL expressing cells survived for up to 7 days. These surviving cells were observed to be spatially distributed and were not in direct physical contact with each other. Upon examination, it was determined that although the majority of the surviving cells expressed FasL, only 30% expressed both Fas and FasL. These cells were capable of inducing apoptosis of target cells and some were also susceptible to FasL expressing cells, provided that the effector and target cells were in close physical contact. FasL/Fas-mediated apoptosis was inhibited by p35, a baculovirus gene that inhibits caspases. Additionally, in contrast to HCASM cells, neither membrane-bound nor soluble FasL induced apoptosis in coronary artery endothelial cells. Conclusions: FasL expressing HCASM cells do not undergo FasL/Fas mediated “suicide” but kill neighboring cells bearing Fas in a “fratricidal” manner. A small population of HCASM cells expresses no surface Fas. These results imply that HCASM cells transduced in vivo with FasL may serve as “scavengers” and exert a bystander effect on surrounding cells that may be enhanced by co-expression of p35. As FasL-mediated apoptosis occurs in coronary arterial smooth muscle but not endothelial cells, FasL may also offer an advantage over other genes for use in restenosis since the latter may indiscriminately delay re-endothelialization at the sites of gene. [ABSTRACT FROM PUBLISHER]

Background: Long-term intraocular injections of vascular endothelial growth factor (VEGF)-neutralising proteins can preserve central vision in many patients with neovascular age-related macular degeneration. We tested the safety and tolerability of a single intravitreous injection of an AAV2 vector expressing the VEGF-neutralising protein sFLT01 in patients with advanced neovascular age-related macular degeneration.Methods: This was a phase 1, open-label, dose-escalating study done at four outpatient retina clinics in the USA. Patients were assigned to each cohort in order of enrolment, with the first three patients being assigned to and completing the first cohort before filling positions in the following treatment groups. Patients aged 50 years or older with neovascular age-related macular degeneration and a baseline best-corrected visual acuity score of 20/100 or less in the study eye were enrolled in four dose-ranging cohorts (cohort 1, 2 × 108 vector genomes (vg); cohort 2, 2 × 109 vg; cohort 3, 6 × 109 vg; and cohort 4, 2 × 1010 vg, n=3 per cohort) and one maximum tolerated dose cohort (cohort 5, 2 × 1010 vg, n=7) and followed up for 52 weeks. The primary objective of the study was to assess the safety and tolerability of a single intravitreous injection of AAV2-sFLT01, through the measurement of eye-related adverse events. This trial is registered with ClinicalTrials.gov, number NCT01024998.Findings: 19 patients with advanced neovascular age-related macular degeneration were enrolled in the study between May 18, 2010, and July 14, 2014. All patients completed the 52-week trial period. Two patients in cohort 4 (2 × 1010 vg) experienced adverse events that were possibly study-drug related: pyrexia and intraocular inflammation that resolved with a topical steroid. Five of ten patients who received 2 × 1010 vg had aqueous humour concentrations of sFLT01 that peaked at 32·7-112·0 ng/mL (mean 73·7 ng/mL, SD 30·5) by week 26 with a slight decrease to a mean of 53·2 ng/mL at week 52 (SD 17·1). At baseline, four of these five patients were negative for anti-AAV2 serum antibodies and the fifth had a very low titre (1:100) of anti-AAV2 antibodies, whereas four of the five non-expressers of sFLT01 had titres of 1:400 or greater. In 11 of 19 patients with intraretinal or subretinal fluid at baseline judged to be reversible, six showed substantial fluid reduction and improvement in vision, whereas five showed no fluid reduction. One patient in cohort 5 showed a large decrease in vision between weeks 26 and 52 that was not thought to be vector-related.Interpretation: Intravitreous injection of AAV2-sFLT01 seemed to be safe and well tolerated at all doses. Additional studies are needed to identify sources of variability in expression and anti-permeability activity, including the potential effect of baseline anti-AAV2 serum antibodies.Funding: Sanofi Genzyme, Framingham, MA, USA. [ABSTRACT FROM AUTHOR]

Mucolipidoses II and III (ML II and ML III) are lysosomal disorders in which the mannose 6-phosphate recognition marker is absent from lysosomal hydrolases and other glycoproteins due to mutations in GNPTAB , which encodes two of three subunits of the heterohexameric enzyme, N-acetylglucosamine-1-phosphotransferase. Both disorders are caused by the same gene, but ML II represents the more severe phenotype. Bone manifestations of ML II include hip dysplasia, scoliosis, rickets and osteogenesis imperfecta. In this study, we sought to determine whether a recombinant adeno-associated viral vector (AAV2/8-GNPTAB) could confer high and prolonged gene expression of GNPTAB and thereby influence the pathology in the cartilage and bone tissue of a GNPTAB knock out (KO) mouse model. The results demonstrated significant increases in bone mineral density and content in AAV2/8-GNPTAB-treated as compared to non-treated KO mice. We also showed that IL-6 (interleukin-6) expression in articular cartilage was reduced in AAV2/8-GNPTAB treated ML II mice. Together, these data suggest that AAV-mediated expression of GNPTAB in ML II mice can attenuate bone loss via inhibition of IL-6 production. This study emphasizes the value of the MLII KO mouse to recapitulate the clinical manifestations of the disease and highlights its amenability to therapy. [ABSTRACT FROM AUTHOR]

Spinal muscular atrophy (SMA) is a neuromuscular disease caused by mutations in survival motor neuron 1 ( SMN1). Previously, we showed that central nervous system (CNS) delivery of an adeno-associated viral (AAV) vector encoding SMN1 produced significant improvements in survival in a mouse model of SMA. Here, we performed a dose-response study in SMA mice to determine the levels of SMN in the spinal cord necessary for efficacy, and measured the efficiency of motor neuron transduction in the spinal cord after intrathecal delivery in pigs and nonhuman primates (NHPs). CNS injections of 5e10, 1e10, and 1e9 genome copies (gc) of self-complementary AAV9 (scAAV9)-hSMN1 into SMA mice extended their survival from 17 to 153, 70, and 18 days, respectively. Spinal cords treated with 5e10, 1e10, and 1e9 gc showed that 70-170%, 30-100%, and 10-20% of wild-type levels of SMN were attained, respectively. Furthermore, detectable SMN expression in a minimum of 30% motor neurons correlated with efficacy. A comprehensive analysis showed that intrathecal delivery of 2.5e13 gc of scAAV9-GFP transduced 25-75% of the spinal cord motor neurons in NHPs. Thus, the extent of gene expression in motor neurons necessary to confer efficacy in SMA mice could be obtained in large-animal models, justifying the continual development of gene therapy for SMA. [ABSTRACT FROM AUTHOR]

Abstract: Clinically effective gene therapy for Cystic Fibrosis has been a goal for over 20 years. A plasmid vector (pGM169) that generates persistent expression and reduced host inflammatory responses in mice has raised prospects for translation to the clinic. The UK CF Gene Therapy Consortium is currently evaluating long-term repeated delivery of pGM169 complexed with the cationic lipid GL67A in a large Multidose Trial. This regulatory-compliant evaluation of aerosol administration of nine doses of pGM169/GL67A at monthly intervals, to the sheep lung, was performed in preparation for the Multidose Trial. All sheep tolerated treatment well with no adverse effects on haematology, serum chemistry, lung function or histopathology. Acute responses were observed in relation to bronchoalveolar cellularity comprising increased neutrophils and macrophage numbers 1 day post-delivery but these increases were transient and returned to baseline. Importantly there was no cumulative inflammatory effect or lung remodelling with successive doses. Molecular analysis confirmed delivery of pGM169 DNA to the airways and pGM169-specific mRNA was detected in bronchial brushing samples at day 1 following doses 1, 5 and 9. In conclusion, nine doses of pGM169/GL67A were well tolerated with no significant evidence of toxicity that would preclude adoption of a similar strategy in CF patients. [Copyright &y& Elsevier]

Salutary responses to adeno-associated viral (AAV) gene therapy have been reported in the mouse model of Sandhoff disease (SD), a neurodegenerative lysosomal storage disease caused by deficiency of β-N-acetylhexosaminidase (Hex). While untreated mice reach the humane endpoint by 4.1 months of age, mice treated by a single intracranial injection of vectors expressing human hexosaminidase may live a normal life span of 2 years. When treated with the same therapeutic vectors used in mice, two cats with SD lived to 7.0 and 8.2 months of age, compared with an untreated life span of 4.5 ± 0.5 months (n = 11). Because a pronounced humoral immune response to both the AAV1 vectors and human hexosaminidase was documented, feline cDNAs for the hexosaminidase α- and β-subunits were cloned into AAVrh8 vectors. Cats treated with vectors expressing feline hexosaminidase produced enzymatic activity >75-fold normal at the brain injection site with little evidence of an immune infiltrate. Affected cats treated with feline-specific vectors by bilateral injection of the thalamus lived to 10.4 ± 3.7 months of age (n = 3), or 2.3 times as long as untreated cats. These studies support the therapeutic potential of AAV vectors for SD and underscore the importance of species-specific cDNAs for translational research. [ABSTRACT FROM AUTHOR]

Abstract: The efficacy of administering a recombinant adeno-associated virus (AAV) vector encoding human IGF-1 (AAV2/1-hIGF-1) into the deep cerebellar nucleus (DCN) of a type III SMA mouse model was evaluated. High levels of IGF-1 transcripts and protein were detected in the spinal cord at 2months post-injection demonstrating that axonal connections between the cerebellum and spinal cord were able to act as conduits for the viral vector and protein to the spinal cord. Mice treated with AAV2/1-hIGF-1 and analyzed 8months later showed changes in endogenous Bax and Bcl-xl levels in spinal cord motor neurons that were consistent with IGF-1-mediated anti-apoptotic effects on motor neurons. However, although AAV2/1-hIGF-1 treatment reduced the extent of motor neuron cell death, the majority of rescued motor neurons were non-functional, as they lacked axons that innervated the muscles. Furthermore, treated SMA mice exhibited abnormal muscle fibers, aberrant neuromuscular junction structure, and impaired performance on motor function tests. These data indicate that although CNS-directed expression of IGF-1 could reduce motor neuron cell death, this did not translate to improvements in motor function in an adult mouse model of type III SMA. [Copyright &y& Elsevier]

Abstract: The cationic lipid GL67A is one of the more efficient non-viral gene transfer agents (GTAs) for the lungs, and is currently being evaluated in an extensive clinical trial programme for cystic fibrosis gene therapy. Despite conferring significant expression of vector-specific mRNA following transfection of differentiated human airway cells cultured on air liquid interfaces (ALI) cultures and nebulisation into sheep lung in vivo we were unable to detect robust levels of the standard reporter gene Firefly luciferase (FLuc). Recently a novel secreted luciferase isolated from Gaussia princeps (GLuc) has been described. Here, we show that (1) GLuc is a more sensitive reporter gene and offers significant advantages over the traditionally used FLuc in pre-clinical models for lung gene transfer that are difficult to transfect, (2) GL67A-mediated gene transfection leads to significant production of recombinant protein in these models, (3) promoter activity in ALI cultures mimics published in vivo data and these cultures may, therefore, be suitable to characterise promoter activity in a human ex vivo airway model and (4) detection of GLuc in large animal broncho-alveolar lavage fluid and serum facilitates assessment of duration of gene expression after gene transfer to the lungs. In summary, we have shown here that GLuc is a sensitive reporter gene and is particularly useful for monitoring gene transfer in difficult to transfect models of the airway and lung. This has allowed us to validate that GL67A, which is currently in clinical use, can generate significant amounts of recombinant protein in fully differentiated human air liquid interface cultures and the ovine lung in vivo. [Copyright &y& Elsevier]

Late infantile neuronal ceroid lipofuscinosis (LINCL) is one of a group of autosomal recessive neurodegenerative diseases caused by deficiencies in lysosomal proteins and characterized clinically by progressive motor and cognitive decline, progressive vision loss, intractable seizures, and premature death. Currently available treatments for these disorders are merely supportive and do not alter disease progression, supporting investigations into novel treatments.Enzyme replacement therapy is a currently available treatment for some lysosomal storage diseases affecting primarily peripheral tissues, but has not been beneficial in those with central nervous system involvement. Enzyme delivery through the cerebrospinal fluid is a potential alternative route to the central nervous system, but it has not been widely studied. Using a transgenic mouse model of LINCL, a pilot study was done to determine the efficiency of enzyme delivery to the CNS following intraventricular injection. Osmotic pumps (Alzet, Cupertino, CA) were used to deliver recombinant tripeptidyl peptidase 1 (TPP1, Genzyme, Cambridge, MA), which is deficient in the mouse. Pumps were implanted subcutaneously in 18 week old mice and delivered 100 ul enzyme (1.6 mg/ml) through a permanently implanted intraventricular cannula at a rate of 1ul/hr. One week after enzyme delivery, immunostaining for TPP1 in brain sections revealed enzyme distribution throughout the meninges, as well as regions of the cerebral cortex, hippocampus, corpus callosum, and areas adjacent to these structures. In addition, TPP1 enzyme activity met or exceeded heterozygous levels throughout the rostral-caudal extent of the brain. This data suggests that the cerebrospinal luid may mediate enzyme uptake in the CNS. Additional studies are underway to determine the effects of this approach on the neuropathological and behavioral phenotypes observed in the TPP1-deficient mouse, as well as to compare the enzyme replacement approach to a viral vector approach in which TPP1 is expressed and secreted from the ependyma via an adeno-associated virus.Molecular Therapy (2006) 13, S84–S84; doi: 10.1016/j.ymthe.2006.08.243 [ABSTRACT FROM AUTHOR]

Liver-directed gene therapy with adeno-associated virus (AAV) vectors effectively treats mouse models of lysosomal storage diseases (LSDs). We asked whether these results were likely to translate to patients. To understand to what extent preexisting anti-AAV8 antibodies could impede AAV8-mediated liver transduction in primates, commonly preexposed to AAV, we quantified the effects of preexisting antibodies on liver transduction and subsequent transgene expression in mouse and nonhuman primate (NHP) models. Using the highest viral dose previously reported in a clinical trial, passive transfer of NHP sera containing relatively low anti-AAV8 titers into mice blocked liver transduction, which could be partially overcome by increasing vector dose tenfold. Based on this and a survey of anti-AAV8 titers in 112 humans, we predict that high-dose systemic gene therapy would successfully transduce liver in >50% of human patients. However, although high-dose AAV8 administration to mice and monkeys with equivalent anti-AAV8 titers led to comparable liver vector copy numbers, the resulting transgene expression in primates was ~1.5-logs lower than mice. This suggests vector fate differs in these species and that strategies focused solely on overcoming preexisting vector-specific antibodies may be insufficient to achieve clinically meaningful expression levels of LSD genes using a liver-directed gene therapy approach in patients. [ABSTRACT FROM AUTHOR]

Due to the lack of acid α-glucosidase (GAA) activity, Pompe mice develop glycogen storage pathology and progressive skeletal muscle dysfunction with age. Applying either gene or enzyme therapy to reconstitute GAA levels in older, symptomatic Pompe mice effectively reduces glycogen storage in skeletal muscle but provides only modest improvements in motor function. As strategies to stimulate muscle hypertrophy, such as by myostatin inhibition, have been shown to improve muscle pathology and strength in mouse models of muscular dystrophy, we sought to determine whether these benefits might be similarly realized in Pompe mice. Administration of a recombinant adeno-associated virus serotype 8 vector encoding follistatin, an inhibitor of myostatin, increased muscle mass and strength but only in Pompe mice that were treated before 10 months of age. Younger Pompe mice showed significant muscle fiber hypertrophy in response to treatment with follistatin, but maximal gains in muscle strength were achieved only when concomitant GAA administration reduced glycogen storage in the affected muscles. Despite increased grip strength, follistatin treatment failed to improve rotarod performance. These findings highlight the importance of treating Pompe skeletal muscle before pathology becomes irreversible, and suggest that adjunctive therapies may not be effective without first clearing skeletal muscle glycogen storage with GAA. [ABSTRACT FROM AUTHOR]

Abstract: We have assessed whether viscoelastic gels known to inhibit mucociliary clearance can increase lipid-mediated gene transfer. Methylcellulose or carboxymethylcellulose (0.25–1.5%) was mixed with complexes of the cationic lipid GL67A and plasmids encoding luciferase and perfused onto the nasal epithelium of mice. Survival after perfusion with 1% CMC or 1% MC was 90 and 100%, respectively. In contrast 1.5% CMC was uniformly lethal likely due to the viscous solution blocking the airways. Perfusion with 0.5% CMC containing lipid/DNA complexes reproducibly increased gene expression by approximately 3-fold (n =16, p <0.05). Given this benefit, likely related to increased duration of contact, we also assessed the effect of prolonging contact time of the liposome/DNA complexes by delivering our standard 80μg DNA dose over either approximately 22 or 60min of perfusion. This independently increased gene transfer by 6-fold (n =8, p <0.05) and could be further enhanced by the addition of 0.5% CMC, leading to an overall 25-fold enhancement (n =8, p <0.001) in gene expression. As a result of these interventions CFTR transgene mRNA transgene levels were increased several logs above background. Interestingly, this did not lead to correction of the ion transport defects in the nasal epithelium of cystic fibrosis mice nor for immunohistochemical quantification of CFTR expression. To assess if 0.5% CMC also increased gene transfer in the mouse lung, we used whole body nebulisation chambers. CMC was nebulised for 1h immediately before, or simultaneously with GL67A/pCIKLux. The former did not increase gene transfer, whereas co-administration significantly increased gene transfer by 4-fold (p <0.0001, n =18). This study suggests that contact time of non-viral gene transfer agents is a key factor for gene delivery, and suggests two methods which may be translatable for use in man. [Copyright &y& Elsevier]

Acute intermittent porphyria (AIP), an autosomal dominant hepatic porphyria due to half-normal hydroxymethylbilane synthase (HMB-synthase) activity, is manifested by life-threatening acute neurological attacks that are precipitated by factors that induce heme biosynthesis. The acute attacks are currently treated with intravenous hemin, but a more continuous therapy is needed, particularly for patients experiencing frequent attacks. Thus, a recombinant AAV8-based serotype vector expressing murine HMB-synthase driven by liver-specific regulatory elements was generated and its effectiveness to prevent the biochemical induction of an acute attack was evaluated in an AIP mouse model. Intraperitoneal administration of the adeno-associated viral (AAV) vector resulted in a rapid and dose-dependent increase of HMB-synthase activity that was restricted to the liver. Stable expression of hepatic HMB-synthase was achieved and wild-type or greater levels were sustained for 36 weeks. When heme synthesis was periodically induced by a series of phenobarbital injections, the treated mice did not accumulate urinary δ-aminolevulinic acid (ALA) or porphobilinogen (PBG), indicating that the expressed enzyme was functional in vivo and prevented induction of the acute attack. Further, rotarod performance and footprint analyses improved significantly. Thus, liver-directed gene therapy provided successful long-term correction of the hepatic metabolic abnormalities and improved neuromotor function in the murine model of human AIP. [ABSTRACT FROM AUTHOR]

The advent of novel adeno-associated virus (AAV) serotype vectors with higher transduction activity has encouraged a re-evaluation of the merits of this delivery platform for a variety of diseases. We report here that administration of a recombinant AAV8–based serotype vector encoding human α-galactosidase A into Fabry mice facilitated more rapid and significantly higher levels of production of the enzyme than an AAV2 vector. This translated into improved clearance of globotriaosylceramide, the glycosphingolipid that accumulates in the lysosomes of affected Fabry cells, and to correction of the peripheral neuropathy shown associated with this disease. The higher levels of α-galactosidase A expression also allowed for a more rapid induction of immunotolerance to the enzyme. Recombinant AAV8 vectors that facilitated hepatic–restricted expression of high levels of α-galactosidase A conferred immunotolerance to the expressed enzyme as early as 30 days post-treatment. Animals expressing lower levels of the hydrolase, such as those treated with an AAV2–based vector or with lower doses of the AAV8–based vector, were also able to develop immunotolerance, but only after a more extended time period. Adoptive transfer of T cells isolated from the spleens of immunotolerized mice suppressed the formation of antibodies in naïve recipient animals, suggesting the possible role of regulatory T cells in effecting this state.Molecular Therapy (2007) 15, 492–500. doi:10.1038/sj.mt.6300066; published online 26 December 2006 [ABSTRACT FROM AUTHOR]

Abstract: Acid sphingomyelinase deficiency is a lysosomal storage disorder in which the defective lysosomal hydrolase fails to degrade sphingomyelin. The resulting accumulation of substrate in the lysosomes of histiocytic cells leads to hepatosplenomegaly and severe pulmonary inflammation. Administration of a recombinant AAV1 vector encoding human acid sphingomyelinase to acid sphingomyelinase knockout (ASMKO) mice effectively reduced the accumulated substrate in all of the affected visceral organs. However, more complete and rapid clearance of sphingomyelin was observed when an AAV8-based serotype vector was used in lieu of AAV1. Importantly, AAV8-mediated hepatic expression of higher and sustained levels of the enzyme also corrected the abnormal cellularity, cell differentials, and levels of the chemokine MIP-1α in the bronchoalveolar lavage fluids of the ASMKO mice. Treatment also reversed the morphological aberrations associated with the alveolar macrophages of ASMKO mice and restored their phagocytic activity. No antibodies to the expressed enzyme were detected when the viral vectors were used in conjunction with a transcription cassette harboring a liver-restricted enhancer/promoter. Together, these data support the continued development of AAV8-mediated hepatic gene transfer as an approach to treat the visceral manifestations observed in individuals with acid sphingomyelinase deficiency. [Copyright &y& Elsevier]

The successful application of gene therapy for the treatment of genetic diseases such as Fabry is reliant on the development of vectors that are safe and that facilitate sustained expression of therapeutic levels of the transgene product. Here, we report that intravenous administration of a recombinant AAV2 vector encoding human α-galactosidase A under the transcriptional control of a liver-restricted enhancer/promoter (AAV2/DC190-αgal) generated significantly higher levels of expression in BALB/c and Fabry mice than could be realized using the ubiquitous CMV promoter (AAV2/CMVHI-αgal). Moreover, AAV2/DC190-αgal-mediated hepatic expression of α-galactosidase A was sustained for 12 months in BALB/c mice and was associated with a significantly reduced immune response to the expressed enzyme. Subsequent challenge of the AAV2/DC190-αgal-treated animals with recombinant human α-galactosidase A at 6 months failed to elicit the production of anti-α-galactosidase A antibodies, suggesting the induction of immune tolerance in these animals. The levels of expression attained with AAV2/DC190-αgal in the Fabry mice were sufficient to reduce the abnormal accumulation of globotriaosylceramide in the liver, spleen, and heart to basal levels and in the kidney by approximately 40% at 8 weeks. Together, these results demonstrate that AAV2-mediated gene transfer that limits the expression of α-galactosidase A to the liver may be a viable strategy for treating Fabry disease. [Copyright &y& Elsevier]

Immunostimulatory CpG motifs have been implicated as a major contributor to the acute inflammatory response associated with nonviral vectors, most prominently seen after systemic delivery of cationic lipid–plasmid DNA (pDNA) complexes. We have shown previously that complexes containing pDNA vectors that have been largely depleted of CpG motifs have significantly reduced acute toxicity when delivered systemically. However, several CpGs remain in these vectors and the toxicity is not negligible, especially at higher doses of complex. To determine the maximal reduction in the acute toxic response that could be achieved by eliminating CpG signaling, we injected cationic lipid–pDNA complexes into transgenic mice that are deficient in Toll-like receptor 9 (TLR9), which is the receptor that recognizes immunostimulatory CpG motifs. We observed significantly decreased adverse hematological changes and liver damage in TLR9−/− mice compared to normal mice and increased survival at higher doses of complex. However, a pronounced loss of lymphocytes and platelets was still observed in the TLR9−/− mice at higher doses. We also measured the toxicity in normal mice of systemically delivered complexes containing non-CpG oligonucleotides. Although serum transaminase levels were reduced, a loss of lymphocytes and platelets akin to that seen in the TLR9−/− mice was observed. Taken together, these findings suggest that signaling through TLR9 contributes to the majority but not all of the toxic responses associated with systemic delivery of cationic lipid–pDNA complexes. [Copyright &y& Elsevier]

Progress towards developing gene therapy for Gaucher disease has been hindered by the lack of an animal model. Here we describe a mouse model of Gaucher disease which has a chemically induced deficiency of glucocerebrosidase and that accumulates elevated levels of glucosylceramide (GL-1) in the lysosomes of Kupffer cells. Administration of mannose-terminated glucocerebrosidase (Cerezyme) resulted in the reduction of GL-1 levels in the livers of these animals. Gene transduction of hepatocytes with a plasmid DNA vector encoding human glucocerebrosidase (pGZB-GC) generated high-level expression and secretion of the enzyme into systemic circulation with consequent normalization of Kupffer cell GL-1 levels. This suggested that the de novo synthesized and unmodified enzyme produced by hepatocyte transduction was also capable of being delivered to the cells that are primarily affected in Gaucher disease. Immunolocalization studies also revealed that preferential transduction and expression of human glucocerebrosidase in the Kupffer cells with subsequent reduction in the GL-1 levels could be attained with a low dose of a recombinant adenoviral vector encoding the human enzyme (Ad2/CMV-GC). This observation raises the possibility of gene therapy for Gaucher disease that involves directly transducing the affected histiocytes using recombinant adenoviral vectors. Together, these data demonstrate the potential for use of in vivo gene therapy vectors for treating Gaucher disease. [Copyright &y& Elsevier]

Systemic delivery of cationic lipid–plasmid DNA (pDNA) complexes induces an acute inflammatory response with adverse hematologic changes and liver damage. Immunostimulatory CpG motifs in the pDNA are known to contribute substantially to this response. Here we constructed a pDNA vector (pGZB) that has been depleted of 80% of the CpG motifs present in the original vector. Compared with the unmodified vector, systemic administration of pGZB induced considerably fewer changes in blood parameters, reduced levels of inflammatory cytokines, and decreased liver damage. Despite the extensive sequence modifications within pGZB, there were still robust levels of transgene expression. Furthermore, in contrast to the transient expression observed from the unmodified vector, we observed sustained or increasing expression for up to 49 days from pGZB in the lung and liver of immunocompetent BALB/c mice. Studies adding CpG motifs in trans or in cis indicate that the reduced CpG content of pGZB was the major determinant for its persistent expression. This combination of decreased toxicity and sustained expression suggests that CpG-depleted pDNA vectors can greatly improve the safety and efficacy of synthetic gene delivery systems. [Copyright &y& Elsevier]

Gene therapy efforts have focused primarily on the use of either the liver or skeletal muscle as depot organs for the production of a variety of therapeutic proteins that act systemically. Here we examined the lung to determine whether it could function as yet another portal for the secretion of proteins into the circulation. Fabry disease is caused by a deficiency of the lysosomal hydrolase α-galactosidase A, resulting in the abnormal deposition of the glycosphingolipid globotriaosylceramide (GL-3) in vascular lysosomes. Pulmonary instillation of a recombinant adenoviral vector (Ad2/CMVHI-αgal) encoding human α-galactosidase A into Fabry mice resulted in high-level transduction and expression of the enzyme in the lung. Importantly, enzymatic activity was also detected in the plasma, liver, spleen, heart, and kidneys of the Fabry mice. The detection of enzymatic activity outside of the lung, along with the finding that viral DNA was limited to the lung, indicates that the enzyme crossed the air/blood barrier, entered the systemic circulation, and was internalized by the distal visceral organs. The levels of α-galactosidase A attained in these tissues were sufficient to reduce GL-3 to basal levels in the lung, liver, and spleen and to ∼ 50% of untreated levels in the heart. Together, these results suggest that the lung may be a viable alternate depot organ for the production and systemic secretion of α-galactosidase A for Fabry disease. [Copyright &y& Elsevier]

Classical late infantile neuronal ceroid lipofuscinosis (cLINCL) is a neurodegenerative disorder that results from the loss of tripeptidyl peptidase I (TPP1) enzyme activity. Patients with cLINCL possess seizures that are frequently associated with blindness, exhibit cognitive and behavioral deficits that are progressive, and death by 7–20 years of age. Accumulation of autofluorescent storage material is a cardinal feature of the disease, as well as axonal degeneration and loss of cortical neurons. A recent study by our group in a knockout mouse model of cLINCL showed that recombinant AAV2 or AAV5 significantly reduced autofluorescent storage and curvilinear bodies in cells of the brain. Reversal of pathology was restricted to injected and nearby structures at a dose of 2.0 e11 genome copies (gc)/ml. To further evaluate AAV gene therapy, a codon-optimized synthetic human CLN2 cDNA was engineered, packaged into AAV1 capsids (AAV1-hCLN2), concentrated to a high titer (3.3 e12 gc/ml), and injected into the CLN2 (−/−) thalamus of one hemisphere. At 1 month post-injection, brain homogenates of the injection site contained TTP1 enzyme activity that was 15-fold higher than corresponding regions of untreated CLN2 (+/+) mice. TPP1 activity was also observed in the rostral and caudal regions of injected hemisphere, and in the contralateral hemisphere at levels 2-fold higher than CLN2 (+/+) controls. These data demonstrate that the AAV1 vector is capable of producing widespread and high levels of TPP1 activity in vivo. A cohort of 4-week old CLN2 (−/−) mice were then injected with AAV1-hCLN2 into multiple structures of the right (striatum, hippocampus, cerebellum) and left (motor cortex, thalamus, medulla) hemispheres to investigate global reversal of pathology, functional recovery, and extension of lifespan. The results of this experiment including behavioral testing and survival data will be presented.Molecular Therapy (2006) 13, S344–S344; doi: 10.1016/j.ymthe.2006.08.982 [ABSTRACT FROM AUTHOR]

The inborn neurodegenerative Tay-Sachs and Sandhoff diseases are caused by mutations in the α and β subunits of β-hexosaminidase A(αβ) (HexA) and B (ββ) (HexB) isozymes, respectively. In the absence of active enzyme GM2 ganglioside and related glycolipids accumulate prominently in neuronal lysosomes. This leads to cell dysfunction, inflammation and finally neuronal loss.Mice homozygous for disrupted β-hexosaminidase β gene (hex β-/-, Sandhoff mouse), an authentic model of human GM2 gangliosidosis, although normal at birth develop a progressive neurodegenerative disease requiring euthanasia by 16 weeks of age.We have used AAV-derived vectors to direct expression of human hex β (hhexβ) and hex α (hhexα) in the brain of Sandhoff mice with the aim of improving outcome by gene therapy, and to further understand disease pathogenesis.One-month old Sandhoff mice were injected with a mixture of AAV2/2 expressing hhexβ (AAVhhexβ) and hhexα (AAVhhexα) or AAVhhexβ and AAVhhexα on their own in the presence of 6% mannitol. Single striatal injections as well as four-site injections, two in the striatum and two in the cerebellum, were performed. All animals treated with AAVhhexα and β or AAVhhexβ alone, and culled at different post-injection times, showed widespread gene expression ipsilaterally and contralaterally, extending from olfactory bulbs to lower spinal cord. Clearance of storage mapped directly to regions where enzymatic activity was present, as determined by PAS staining and electronmicroscopy, and microglia expansion/ activation was absent in these regions. Expression of hhexβ alone led to an increase in HexA wich was higher than in wild type controls. Six untreated hex β-/- mice had onset of symptoms by 96±13 (sd) days and reached their humane end-point at 120±4 days. A group receiving control injections of AAVhhexα alone had a similar evolution of symptoms and humane end points at 101±8 and 119.5±5 days, respectively. In contrast, 43% of animals recieving four-site injections of AAVhhexβ alone survived to more than one year of age, while six mice receiving a mixture of AAVhhexα and AAVhhexβ had delayed symptoms and reached the humane end point at 199±17 days (p<0.0001). Gene therapy intervention in this null mutant model of Sandhoff disease dramatically increased survival; improved neuronal function with concomitant maintenance of motor coordination, balance, body weight, and delayed ataxia and tremor; as well as reducing the inflammatory response. Co-injection of AAVhhexα with AAVhhexβ was not required for the formation of therapeutic levels of HexA.Molecular Therapy (2006) 13, S86–S87; doi: 10.1016/j.ymthe.2006.08.251 [ABSTRACT FROM AUTHOR]

We are developing synthetic,targeted vector systems for the respiratory system to treat diseases such as cystic fibrosis (CF). Lip/Tide-I vectors comprised an integrin-targeting peptide and DOTMA/DOPE which displayed transfected human epithelial cells with low receptor specificity due to a lack of integrin receptors. The integrin-targeting motif was replaced with an epithelial targeting peptide selected by phage display panning on human airway epithelial cells. The cationic lipid was optimised by substituting DOTMA, which has an eighteen-carbon alkyl tail (C18), with a C16 cationic lipid.The epithelial-optimised Lip/Tide vector (Lip/Tide-E) was compared with Lip/Tide-I in transfections of cultured human airway epithelial cells and in vivo by tracheal instillation into murine lungs of fifty microlitres of vector containing 8–16 micrograms of DNA. Lip/Tide-E transfection in human epithelial cells was eight-fold higher than Lip/Tide-I with high specificity of receptor-mediated transfection but did not enhance transfection in vivo owing to species specificity. The lipid enhanced luciferase transfection in human epithelial cells about ten-fold and in murine lung in vivo by two- fold.Luciferase expression in mouse whole lung extracts was compared after one and three doses of Lip/Tide-E vector. Single dose expression levels of Lip/Tide (2,400 RLU/mg) were similar to levels with GL67 (Genzyme), a vector used in CF gene therapy trials, and about twice the level achieved with polyethylenimine (PEI 25 kDa). After three weekly doses of Lip/Tide vector, luciferase expression was equivalent to single dose levels. Immunohistochemical staining of lung sections revealed that the Lip/Tide-transfected luciferase activity was located mainly in airway epithelium, with some further transfection of macrophages, while GL67 activity was largely in macrophages. A moderate Lip/Tide-mediated inflammatory cell infiltration was apparent and levels of inflammatory cytokines from bronchoalveolar lavage fluids, particularly IL-6 and IL-12, were elevated 24 h after transfection. The vector retained its transfection efficiency after nebulisation as evaluated in luciferase assays after in vitro and in vivo administration.In summary, the Lip/Tide-E vector transfection efficiency in human epithelial cells in vitro and in the airway epithelium of mouse lung is superior to Lip/Tide-I and compares well with established vectors such as GL67 and PEI. The modest inflammatory response and the ability to re-administer the Lip/Tide vector to restore gene expression are important requirements of a respiratory gene transfer system although further improvements to the inflammatory profile may be achieved by using CpG-depleted plasmids. The vector is compatible with delivery by aerosol inhalation which requires further evaluation in large animal models.Molecular Therapy (2006) 13, S269–S270; doi: 10.1016/j.ymthe.2006.08.774 [ABSTRACT FROM AUTHOR]

Nonviral gene therapy is being developed for the treatment of Cystic Fibrosis (CF) lung disease. To date, such approaches have been limited by the poor duration of expression observed and a have also resulted in inflammatory responses following delivery of lipid/ plasmid DNA (pDNA) complexes to the lungs of mice and human subjects. This inflammatory response appears to be due in part to the detection by toll-like receptor 9 of CpG motifs present in pDNA. The majority of first generation pDNA vectors used in pre-clinical and clinical studies contained a large number of immune-stimulatory CpG motifs and one approach to reducing inflammation is to reduce or completely remove CpGs from the pDNA. Therefore we have constructed two novel series of pDNA vectors. Second generation pDNA vectors were constructed from elements with a low CpG content (such as the Genzyme ΔCpG plasmid backbone), which reduced the overall number of CpGs by approximately 50%. Third generation plasmids were constructed from elements that contained no CpG motifs (ΔCpG R6K origin, ΔCpG ZeoR, Murine CMV enhancer, human EF1a promoter) to produce zero-CpG plasmids. Versions of these plasmids that expressed luciferase reporter gene were complexed with Genzyme lipid 67 and delivered to mouse lung by nasal instillation (BALB/c, n=10, 80μg pDNA/100μl). At 24-hours post-dosing, bronchoalveolar lavage fluid (BALF) was collected and the level of IL-12, IFN-γ, TNF-α and total cells was determined. Untreated controls mice had very low levels of all four markers (0%). Mice that received CpG-rich first generation plasmid complexes had elevated levels of all four inflammatory markers (100%). Delivery of second generation (CpG-reduced) plasmids to the mouse lung did not significantly reduce levels IL-12 (105%), TNF-α (60%), IFN-γ (86%) or total cells (80%) (Mann-Whitney U P>0.05). However, following delivery of third generation (zero- CpG) plasmid complexes, levels of IL-12 (10%), TNF-α (0%), IFN-γ (4%) and total cells (14%) were indistinguishable from untreated control mice (P<0.01). Furthermore, at 24-hours post- dosing, luciferase activity in the lung was 10-fold higher from third generation plasmids compared with all other treated groups (P<0.001). In addition, expression from the zero-CpG plasmids persisted for at least 60 days post-dosing while the CpG containing plasmids resulted in only transient expression in the mouse lung (<7 days). These studies suggest that partial reduction of CpG content is no sufficient to reduce the inlfammation observed in mouse lung airway gene transfer models. However the lack of an inflammatory response following delivery of zero-CpG plasmids suggests that these vectors represent a significant advance in terms of safety and efficacy of nonviral delivery to the lung. Further studies outlining the development and testing of clinically relevant zero-CpG will also be presented.Molecular Therapy (2006) 13, S304–S305; doi: 10.1016/j.ymthe.2006.08.873 [ABSTRACT FROM AUTHOR]