ABSTRACT: AAV capsid variants with brain-wide transgene expression and decreased liver targeting after intravenous delivery in mouse and marmoset - BioProject
Project description:The study of microglia biology and the development of microglia-based gene therapies are in urgent need of efficient and safe vehicles for microglia transgene delivery. To address this, we developed adeno-associated virus (AAV) variants that mediate efficient in vitro and in vivo microglia transduction via directed evolution of the AAV capsid protein. To assess the effect of AAV transduction on microglia, we carried out bulk RNAseq in primary microglia and found that microglia transduced by AAV remain close to homeostatic state. Furthermore, single-cell RNA sequencing showed that the AAV-MG variants mediate safe in vivo transgene delivery without inducing microglia immune activation. These AAV variants should facilitate the applications of various genetically-encoded sensors and effectors in studying microglia-related biology and therapeutic interventions.
2022-04-06 | GSE197743 | GEO
Project description:Targeting the lung epithelium after intravenous delivery by directed evolution of underexplored sites on AAV capsid
Project description:Adeno-associated virus (AAV) has emerged as a leading platform for gene therapy. With a skyrocketing rate of AAV research and the prevalence of many new engineered capsids being investigated in preclinical and clinical trials, capsid characterization plays an important role in serotype confirmation and quality control. Further, peptide mapping the capsid proteins might inevitably be a future requirement by regulatory agencies since it is a critical step in good manufacturing practice (GMP) for biotherapeutic characterization. To overcome many challenges that traditional methods like SDS-PAGE and Western blots carry, liquid chromatography & mass spectrometry (LC-MS) allows high resolution & sensitivity with great confidence in characterizing the AAV capsid proteins to the exact masses. Our optimized LC-MS method provides quick sample preparation, fast and high-throughput 4-min run, high sensitivity (only need ~2E10 vg per run for UV detection) allowing very efficient characterization of wild-type and engineered capsids. Additionally, , as well as LC-MS/MS peptide mapping of the AAV capsid proteins, including. lLysine-targeted chemical modification of the AAV capsids, for the first time, was characterized and peptide mapped in this study, therefore elucidating the most accessible Lysine residues of the AAV tested. Our detailed protocols method areis anticipated to promote the development and discovery of AAV variants with high accuracy and efficiency.
Project description:Zhu et al. report the application of single-cell RNA-sequencing technology for profiling the cell-specific transgene expression and transcriptome dysregulation in mouse liver following intravenous administration of AAV vectors. By profiling 46,500 mouse liver cells, we have identified 3 separate clusters of hepatocytes (hep1, hep2 and hep3), endothelial cells, Kupffer cells and lymphocytes. Assessment of the AAVrh.10mCherry treated liver demonstrated transgene expression in not only hepatocytes, but in all cell types, with significant cell-type-specific expression heterogeneity. Large numbers of cell type-specific genes were up- and down-regulated in response to the AAV vectors. These observations provide insights into the liver cell-specific consequences of AAV-mediated liver gene transfer, far beyond the well-known organ-specific expression of the vector-delivered transgene.
Project description:CRISPR-based gene editing technology represents a promising approach to deliver therapies for inherited disorders, including amyotrophic lateral sclerosis (ALS). Toxic gain-of-function superoxide dismutase 1 (SOD1) mutations are responsible for ~20% of familial ALS cases. Thus, current clinical strategies to treat SOD1-ALS are designed to lower SOD1 levels. Here, we utilized AAV-PHP.B variants to deliver CRISPR-Cas9 guide RNAs designed to disrupt the human SOD1 (huSOD1) transgene in SOD1G93A mice. A one-time intracerebroventricular injection of AAV.PHP.B-huSOD1-sgRNA into neonatal H11Cas9 SOD1G93A mice caused robust and sustained mutant huSOD1 protein reduction in the cortex and spinal cord, and restored motor function. Neonatal treatment also reduced spinal motor neuron loss, neuromuscular junction (NMJ) denervation and muscle atrophy, diminished axonal damage and preserved compound muscle action potential throughout the lifespan of treated mice. SOD1G93A treated mice achieved significant disease-free survival, extending lifespan by more than 110 days. Importantly, a one-time intrathecal or intravenous injection of AAV.PHP.eB-huSOD1-sgRNA in adult H11Cas9 SOD1G93A mice, immediately before symptom onset, also extended lifespan by at least 170 days. We observed substantial protection against disease progression demonstrating the utility of our CRISPR editing preclinical approach for target evaluation. Our work not only uncovered key parameters (e.g., AAV capsid, Cas9 expression) that resulted in improved efficacy compared similar approaches but can also serve to accelerate drug target validation.
Project description:Rett syndrome is an incurable neurodevelopmental disorder caused by mutations in the gene encoding for methyl-CpG binding-protein 2 (MeCP2). Gene therapy for this disease presents inherent hurdles since MECP2 is expressed throughout the brain and its duplication leads to severe neurological conditions as well. Herein, we use the AAV-PHP.eB to deliver an instability-prone Mecp2 (iMecp2) transgene cassette which, increasing RNA destabilization and inefficient protein translation of the viral Mecp2 transgene, limits supraphysiological Mecp2 protein levels. Intravenous injections of the PHP.eB-iMecp2 virus in symptomatic Mecp2 mutant mice significantly improved locomotor activity, lifespan and gene expression normalization. Remarkably, PHP.eB-iMecp2 administration was well tolerated in female Mecp2 mutant or in wild-type animals. In contrast, we observed a strong immune response to the transgene in treated male Mecp2 mutant mice that was overcome by immunosuppression. Overall, PHP.eB-mediated delivery of iMecp2 provided widespread and efficient gene transfer maintaining physiological Mecp2 protein levels in the brain.
Project description:Despite rapid progress in the development of new therapies based on adeno-associated viral vectors (AAVs) in recent years, successful transduction of the human heart remains challenging. So far, the mechanisms that impede AAV transduction, especially in humans are poorly understood, hampering the introduction of new, effective gene therapy strategies. Therefore, the aim of this study was to identify and overcome the main cellular barriers to successful transduction in the heart, using iPSC-derived cardiomyocytes (iPSC-CMs), cardiac fibroblasts (iPSC-CFs), and primary endothelial cells (HAECs) to model vector-host interactions. Through phosphoproteome analysis of AAV9-transduced iPSC-CFs we established that casein kinase 2 (CK2) signalling is one of the most significantly affected pathways upon AAV exposure. Importantly, transient inhibition of CK2 activity with silmitasertib substantially enhanced the transduction rate of AAV2, AAV6 and AAV9 in all tested cell types (iPSC-CMs, iPSC-CFs and HAECs), demonstrating the versatility of this approach. CK2 inhibition improved the trafficking of AAVs through the cytoplasm and impaired DNA-damage response through destabilisation of Mre11, sensor of dsDNA breaks, that directly binds the ITRs of the vector genome. Silmitasertib treatment also allowed for improvement of transgene expression in already transduced iPSC-CFs, which retain AAV genomes in a functional, but probably silent form. Furthermore, our analysis revealed that AAV transduction may interfere with RNA processing pathways, identifying matrin-3 as a necessary factor for efficient transgene delivery. In summary, presented study provides new insights into the current understanding of the host-AAV vector interaction, identifying CK2 activity as a key barrier to efficient transduction and transgene expression, therefore offering a promising strategy to improve the outcome of AAV-based therapies in the future.
Project description:Recombinant adeno-associated viral vectors (rAAVs) are among the most commonly used vehicles for in vivo based gene therapies. However, it is hard to predict which AAV capsid will provide the most robust expression in human subjects due to the observed discordance in vector-mediated transduction between species. We used a primate specific capsid, AAV-LK03, and demonstrated that the limitation of this capsid towards transduction of mouse cells was unrelated to cell entry and nuclear transport but rather due to depleted histone H3 chemical modifications related to active transcription, namely H3K4me3 and H3K27ac, on the vector DNA itself. A single-amino acid insertion into the AAV-LK03 capsid enabled efficient transduction and the accumulation of active-related epigenetic marks on the vector chromatin in mouse without compromising transduction efficiency in human cells. Our study suggests that the capsid protein itself is involved in driving the epigenetic status of the vector genome, most likely during the process of uncoating. Programming viral chromatin states by capsid design may enable facile DNA transduction between vector and host species and ultimately led to rationale selection of AAV capsids for use in humans.
Project description:Recombinant adeno-associated viral vectors (rAAVs) are among the most commonly used vehicles for in vivo based gene therapies. However, it is hard to predict which AAV capsid will provide the most robust expression in human subjects due to the observed discordance in vector-mediated transduction between species. We used a primate specific capsid, AAV-LK03, and demonstrated that the limitation of this capsid towards transduction of mouse cells was unrelated to cell entry and nuclear transport but rather due to depleted histone H3 chemical modifications related to active transcription, namely H3K4me3 and H3K27ac, on the vector DNA itself. A single-amino acid insertion into the AAV-LK03 capsid enabled efficient transduction and the accumulation of active-related epigenetic marks on the vector chromatin in mouse without compromising transduction efficiency in human cells. Our study suggests that the capsid protein itself is involved in driving the epigenetic status of the vector genome, most likely during the process of uncoating. Programming viral chromatin states by capsid design may enable facile DNA transduction between vector and host species and ultimately led to rationale selection of AAV capsids for use in humans.
Project description:Recombinant adeno-associated viral vectors (rAAVs) are among the most commonly used vehicles for in vivo based gene therapies. However, it is hard to predict which AAV capsid will provide the most robust expression in human subjects due to the observed discordance in vector-mediated transduction between species. We used a primate specific capsid, AAV-LK03, and demonstrated that the limitation of this capsid towards transduction of mouse cells was unrelated to cell entry and nuclear transport but rather due to depleted histone H3 chemical modifications related to active transcription, namely H3K4me3 and H3K27ac, on the vector DNA itself. A single-amino acid insertion into the AAV-LK03 capsid enabled efficient transduction and the accumulation of active-related epigenetic marks on the vector chromatin in mouse without compromising transduction efficiency in human cells. Our study suggests that the capsid protein itself is involved in driving the epigenetic status of the vector genome, most likely during the process of uncoating. Programming viral chromatin states by capsid design may enable facile DNA transduction between vector and host species and ultimately led to rationale selection of AAV capsids for use in humans.