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:AAV capsid variants with brain-wide transgene expression and decreased liver targeting after intravenous delivery in mouse and marmoset - BioProject
Project description:Precise targeting of large transgenes to T cells using homology-directed repair has been transformative for adoptive cell therapies and T cell biology. Non-toxic delivery of DNA templates via adeno-associated virus (AAV) has greatly improved knock-in efficiencies, but the tropism of current AAV serotypes restricts their use to human T cells employed in immunodeficient mouse models. To enable targeted knock-ins in murine T cells, we evolved Ark313, a synthetic AAV that exhibits high transduction efficiency in murine T cells. We performed a genome-wide knockout screen and identified QA2 as an essential factor for Ark313 infection. We demonstrate that Ark313 can be used for nucleofection-free DNA delivery, CRISPR/Cas9-mediated knockouts, and targeted integration of large transgenes. Ark313 enables pre-clinical modeling of Trac-targeted CAR-T and transgenic TCR-T cells in immunocompetent models. Efficient gene targeting in murine T cells holds great potential for improved cell therapies and opens new avenues in experimental T cell immunology.
Project description:Long-range gene editing by homology-directed repair (HDR) in hematopoietic stem/progenitor cells (HSPCs) often relies on viral transduction with recombinant adeno-associated viral vector (AAV) for template delivery. Here, we uncover unexpected load and prolonged persistence of AAV genomes and their fragments, which trigger sustained p53-mediated DNA damage response (DDR) upon recruiting the MRE11-RAD50-NBS1 (MRN) complex on the AAV inverted terminal repeats (ITRs). Accrual of viral DNA in cell-cycle-arrested HSPCs led to its frequent integration, predominantly in the form of transcriptionally competent ITRs, at nuclease on- and off-target sites. Optimized delivery of integrase-defective lentiviral vector (IDLV) induced lower DNA load and less persistent DDR, improving clonogenic capacity and editing efficiency in long- term repopulating HSPCs. Because insertions of viral DNA fragments are less frequent with IDLV, its choice for template delivery mitigates the adverse impact and genotoxic burden of HDR editing and should facilitate its clinical translation in HSPC gene therapy.
Project description:Long-range gene editing by homology-directed repair (HDR) in hematopoietic stem/progenitor cells (HSPCs) often relies on viral transduction with recombinant adeno-associated viral vector (AAV) for template delivery. Here, we uncover unexpected load and prolonged persistence of AAV genomes and their fragments, which trigger sustained p53-mediated DNA damage response (DDR) upon recruiting the MRE11-RAD50-NBS1 (MRN) complex on the AAV inverted terminal repeats (ITRs). Accrual of viral DNA in cell-cycle-arrested HSPCs led to its frequent integration, predominantly in the form of transcriptionally competent ITRs, at nuclease on- and off-target sites. Optimized delivery of integrase-defective lentiviral vector (IDLV) induced lower DNA load and less persistent DDR, improving clonogenic capacity and editing efficiency in long- term repopulating HSPCs. Because insertions of viral DNA fragments are less frequent with IDLV, its choice for template delivery mitigates the adverse impact and genotoxic burden of HDR editing and should facilitate its clinical translation in HSPC gene therapy.
Project description:Adeno-associated virus (AAV) vectors are important delivery platforms for therapeutic genome editing but are severely constrained by cargo limits, especially for large effectors like Cas9s. Simultaneous delivery of multiple vectors can limit dose and efficacy and increase safety risks. The use of compact effectors has enabled single-AAV delivery of Cas9s with 1-3 guides for edits that use end-joining repair pathways, but many precise edits that correct disease-causing mutations in vivo require homology-directed repair (HDR) templates. Here, we describe single-vector, ~4.8-kb AAV platforms that express Nme2Cas9 and either two sgRNAs to produce segmental deletions, or a single sgRNA with an HDR template. We also examine the utility of Nme2Cas9 target sites in the vector for self-inactivation. We demonstrate that these platforms can effectively treat two disease models [type I hereditary tyrosinemia (HT-I) and mucopolysaccharidosis type I (MPS-I)] in mice. These results will enable single-vector AAVs to achieve diverse therapeutic genome editing outcomes.
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.