ABSTRACT: Genotoxicity after adeno-associated virus (AAV) gene therapy is dependent upon dose, treatment age and enhancer-promoter selection (microRNA)
Project description:AAV gene therapy has recently been approved for clinical use and shown to be efficacious and safe in a growing number of clinical trials. However, the safety of AAV as a gene therapy has been challenged by a few studies that documented hepatocellular carcinoma (HCC) after AAV gene delivery in mice. The association between AAV and HCC has been difficult to reconcile and is the subject of intense debate because numerous AAV studies have not reported toxicity. Here, we report a comprehensive study of HCC in a large number of mice following therapeutic AAV gene delivery. Using a sensitive high-throughput integration site-capture technique and global expressional analysis, we found that AAV integration into the Rian locus and the over-expression of a proximal gene, Rtl1, were associated with HCC. In addition, we identify a number of genes with differential expression that maybe useful in the study, diagnosis and treatment of HCC. We demonstrate that AAV vector dose, enhancer-promoter selection, and the timing of gene delivery are the defining factors in AAV-mediated insertional mutagenesis. Our results help explain the AAV-mediated genotoxicity previously observed and have important implications for the design of both safer AAV vectors and gene therapy studies. To investigate the possibility that insertional mutagenesis by AAV contributed to the development of HCC, we collected normal and tumor tissues from adult mouse livers that received AAV injection at a neonatal stage.
Project description:AAV gene therapy has recently been approved for clinical use and shown to be efficacious and safe in a growing number of clinical trials. However, the safety of AAV as a gene therapy has been challenged by a few studies that documented hepatocellular carcinoma (HCC) after AAV gene delivery in mice. The association between AAV and HCC has been difficult to reconcile and is the subject of intense debate because numerous AAV studies have not reported toxicity. Here, we report a comprehensive study of HCC in a large number of mice following therapeutic AAV gene delivery. Using a sensitive high-throughput integration site-capture technique and global expressional analysis, we found that AAV integration into the Rian locus and the over-expression of a proximal gene, Rtl1, were associated with HCC. In addition, we identify a number of genes with differential expression that maybe useful in the study, diagnosis and treatment of HCC. We demonstrate that AAV vector dose, enhancer-promoter selection, and the timing of gene delivery are the defining factors in AAV-mediated insertional mutagenesis. Our results help explain the AAV-mediated genotoxicity previously observed and have important implications for the design of both safer AAV vectors and gene therapy studies. To investigate the possibility that insertional mutagenesis by AAV contributed to the development of HCC, we collected normal and tumor tissues from adult mouse livers that received AAV injection at a neonatal stage.
Project description:AAV gene therapy has recently been approved for clinical use and shown to be efficacious and safe in a growing number of clinical trials. However, the safety of AAV as a gene therapy has been challenged by a few studies that documented hepatocellular carcinoma (HCC) after AAV gene delivery in mice. The association between AAV and HCC has been difficult to reconcile and is the subject of intense debate because numerous AAV studies have not reported toxicity. Here, we report a comprehensive study of HCC in a large number of mice following therapeutic AAV gene delivery. Using a sensitive high-throughput integration site-capture technique and global expressional analysis, we found that AAV integration into the Rian locus and the over-expression of a proximal gene, Rtl1, were associated with HCC. In addition, we identify a number of genes with differential expression that maybe useful in the study, diagnosis and treatment of HCC. We demonstrate that AAV vector dose, enhancer-promoter selection, and the timing of gene delivery are the defining factors in AAV-mediated insertional mutagenesis. Our results help explain the AAV-mediated genotoxicity previously observed and have important implications for the design of both safer AAV vectors and gene therapy studies.
Project description:AAV gene therapy has recently been approved for clinical use and shown to be efficacious and safe in a growing number of clinical trials. However, the safety of AAV as a gene therapy has been challenged by a few studies that documented hepatocellular carcinoma (HCC) after AAV gene delivery in mice. The association between AAV and HCC has been difficult to reconcile and is the subject of intense debate because numerous AAV studies have not reported toxicity. Here, we report a comprehensive study of HCC in a large number of mice following therapeutic AAV gene delivery. Using a sensitive high-throughput integration site-capture technique and global expressional analysis, we found that AAV integration into the Rian locus and the over-expression of a proximal gene, Rtl1, were associated with HCC. In addition, we identify a number of genes with differential expression that maybe useful in the study, diagnosis and treatment of HCC. We demonstrate that AAV vector dose, enhancer-promoter selection, and the timing of gene delivery are the defining factors in AAV-mediated insertional mutagenesis. Our results help explain the AAV-mediated genotoxicity previously observed and have important implications for the design of both safer AAV vectors and gene therapy studies.
Project description:Recombinant adeno-associated virus (AAV) is the leading platform for gene therapy in ocular disease. Progress for gene therapy has been hindered by AAV-induced inflammation, which limits dose escalation and long-term efficacy. Characterisation of the ocular immune response to AAV in mice has been restricted to young animals and demonstrate activation of microglia, antigen presentation and a dominant T cell lymphocyte infiltration. The extent of the inflammatory response alters with age and sex and these factors have not been fully represented in the pre-clinical development of ocular AAV gene therapies. Here, we intravitreally inject a null AAV2 vector in young (3-month), middle aged (9-month) and old (18-month) Cx3cr1-creER:R26tdTomato+/- mice of both sexes. Applying clinical imaging, flow cytometric analyses and bulk-sequencing of sorted resident microglia we interrogate the impact of sex and age on the longitudinal response of both microglia and infiltrating cellular response to AAV. Young animals have a dynamic response, with a peak in inflammation at D10-12 and signs of clinical resolution by D28. Despite similar kinetics in the inflammatory response between young male and females, sex differences are observed in the magnitude of the transcriptional response by microglia and the adaptive component of the infiltrating response. With age, the inflammation increases and persists after AAV2 injection. Based on the microglia transcriptional response to AAV, males maintain similar signature across age, although enhanced with increasing age. Contrary, females have greater divergence in their inflammatory response across age. Of particular note, old females have enriched cellular stress and inflammatory microglia gene signatures, with corresponding retinal degeneration. These findings inform crucial sex and age differences for therapeutic application of ocular gene therapy. Our dataset highlight the need to further define these differences to appropriately tackle AAV immunogenicity for all populations.
Project description:The adult mammalian brain entails a reservoir of neural stem cells (NSCs) generating glial cells and neurons. However, NSCs become increasingly quiescent with age, which hampers their regenerative capacity. New means are therefore required to genetically modify adult NSCs for re-enabling endogenous brain repair. Recombinant adeno-associated viruses (AAVs) are ideal gene therapy vectors due to an excellent safety profile and high transduction efficiency. We thus conducted a high-throughput screening of 157 intraventricularly injected barcoded AAV variants profiled by transcriptome sequencing. Transcriptome analysis identified two synthetic capsids, AAV9_A2 and AAV1_P5 transducing active and quiescent NSCs. Further optimization of AAV1_P5 by judicious selection of promoter and dose of injected viral genomes enabled targeting of 57% of the NSC compartment. Importantly, transduced NSC readily produced neurons. The present study identifies AAV variants with a high specificity and transduction efficiency of adult NSCs thereby paving the way for preclinical testing of regenerative gene therapy. We identified a synthetic Adeno-associated virus (AAV) capsid, AAV1_P5, that transduces active and quiescent neural stem cells (NSCs). In order to fully characterize the identity of AAV1_P5-transduced cells, as well as potential changes arising by the AAV-transduction itself, we profiled these cells and untransduced ones from the same mouse by single cell RNA sequencing. To this end, three months-old eYFP-reporter mice were injected with 109 vg/mouse AAV1_P5 harboring the CMV_Cre construct. Transduction induces expression of eYFP. 37 days post injection, we isolated cells from the v-SVZ and other brain regions. More precisely, we isolated labeled cells of the ventricular-subventricular zone and the striatum, rostral migratory stream (RMS) and olfactory bulb, here referred to as rest of the brain (RoB). To capture the remaining unlabeled cells of the NSC-lineage in the v-SVZ, we also isolated GLAST+ v-SVZ cells. Two samples of two pooled mice each were subjected to single cell RNA sequencing.
Project description:Black six animals received either an Adeno associated virus leading to overexpression of Luciferase or Histone deacetyase 4 aminoacids 1-201. After 3 weeks of expression, animals got transaortic banding (TAC) to induce pathological cardiac remodeling. We compared both groups to Back six animals with sham surgery and overexpression of Luziferase. 3 male animals per group (5 replicates) at an age of 8 weeks were treated with an adenoassociated virus (AAV) containing a coding sequence for Luziferase or Histone Deacetylase 4 (aminoacids 1-201) und der the control of the MLC-promoter. Both groups were then exposed to transaortic constriction. As a control served AAV treated animals with overepression of luziferase and sham.
Project description:Microarray analysis of liver RNA from male Low Density Lipoprotein Receptor null mice on C57B6 background expressing human LXR alpha or GFP (control) via adeno-associated virus (AAV2.8) gene transfer, under control of the liver specific human thyroxine binding globulin promoter. Samples are from 8 month old mice, with AAV treatment at age of 10 weeks, on Western diet for 12 weeks prior experiment. The synthetic LXR ligand T0901317 (5mg/kg) or vehicle was administered for 3 days by i.p. injection to designated mice.
Project description:Adeno-associated viral vectors (AAV) are a leading delivery system for gene therapy in animal models and humans. With several FDA-approved AAV gene therapies on the market, issues related to vector manufacturing have become increasingly important. In this study, we focused on potentially toxic DNA contaminants that can arise from AAV proviral plasmids, the raw materials required for manufacturing recombinant AAV in eukaryotic cells. Typical AAV proviral plasmids are circular DNAs containing a therapeutic gene cassette flanked by natural AAV inverted terminal repeat (ITR) sequences, and a plasmid backbone carrying prokaryotic sequences required for plasmid replication and selection in bacteria. While the majority of AAV particles package the intended therapeutic payload, some capsids instead package the bacterial sequences located on the proviral plasmid backbone. Since ITR sequences also have promoter activity, potentially toxic bacterial open reading frames can be produced in vivo, thereby representing a safety risk. In this study, we describe a new AAV proviral plasmid for vector manufacturing that (1) significantly decreases cross-packaged bacterial sequences; (2) increases correctly packaged AAV payloads; and (3) blunts ITR-driven transcription of cross-packaged material to avoid expressing potentially toxic bacterial sequences. This system may help improve the safety of AAV vector products.