scholarly journals Broad gene expression throughout the mouse and marmoset brain after intravenous delivery of engineered AAV capsids

2020 ◽  
Author(s):  
Nicholas C. Flytzanis ◽  
Nick Goeden ◽  
David Goertsen ◽  
Alexander Cummins ◽  
James Pickel ◽  
...  
Keyword(s):  
Viral Vectors ◽  
Therapeutic Option ◽  
Basic Research ◽  
High Specificity ◽  
Therapeutic Interventions ◽  
Cell Type ◽  
Cell Type Specificity ◽  
Gene Therapies ◽  
Screening Platform ◽  
The Brain

ABSTRACTGenetic intervention is increasingly explored as a therapeutic option for debilitating disorders of the central nervous system. The safety and efficacy of gene therapies relies upon expressing a transgene in affected cells while minimizing off-target expression. To achieve organ/cell-type specific targeting after intravenous delivery of viral vectors, we employed a Cre-transgenic-based screening platform for fast and efficient capsid selection, paired with sequential engineering of multiple surface-exposed loops. We identified capsid variants that are enriched in the brain and detargeted from the liver in mice. The improved enrichment in the brain extends to non-human primates, enabling robust, non-invasive gene delivery to the marmoset brain following IV administration. Importantly, the capsids identified display non-overlapping cell-type tropisms within the brain, with one exhibiting high specificity to neurons. The ability to cross the blood–brain barrier with cell-type specificity in rodents and non-human primates enables new avenues for basic research and potential therapeutic interventions unattainable with naturally occurring serotypes.

scholarly journals Tissue-Specific Transcriptional Targeting of a Replication-Competent Retroviral Vector

2002 ◽  
Vol 76 (24) ◽  
pp. 12783-12791 ◽  
Author(s):  
Christopher R. Logg ◽  
Aki Logg ◽  
Robert J. Matusik ◽  
Bernard H. Bochner ◽  
Noriyuki Kasahara
Keyword(s):  
Tumor Cells ◽  
Viral Vectors ◽  
High Efficiency ◽  
Leukemia Virus ◽  
Transduction Efficiency ◽  
Promoter Strength ◽  
Cell Type ◽  
Cell Type Specificity ◽  
Tissue Specific

ABSTRACT The inability of replication-defective viral vectors to efficiently transduce tumor cells in vivo has prevented the successful application of such vectors in gene therapy of cancer. To address the need for more efficient gene delivery systems, we have developed replication-competent retroviral (RCR) vectors based on murine leukemia virus (MLV). We have previously shown that such vectors are capable of transducing solid tumors in vivo with very high efficiency. While the natural requirement of MLV infection for cell division imparts a certain degree of specificity for tumor cells, additional means for confining RCR vector replication to tumor cells are desirable. Here, we investigated the parameters critical for successful tissue-specific transcriptional control of RCR vector replication by replacing various lengths of the MLV enhancer/promoter with sequences derived either from the highly prostate-specific probasin (PB) promoter or from a more potent synthetic variant of the PB promoter. We assessed the transcriptional specificity of the resulting hybrid long terminal repeats (LTRs) and the cell type specificity and efficiency of replication of vectors containing these LTRs. Incorporation of PB promoter sequences effectively restricted transcription from the LTR to prostate-derived cells and imparted prostate-specific RCR vector replication but required the stronger synthetic promoter and retention of native MLV sequences in the vicinity of the TATA box for optimal replicative efficiency and specificity. Our results have thus identified promoter strength and positioning within the LTR as important determinants for achieving both high transduction efficiency and strict cell type specificity in transcriptionally targeted RCR vectors.

scholarly journals A scalable platform for the development of cell-type-specific viral drivers

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Sinisa Hrvatin ◽  
Christopher P Tzeng ◽  
M Aurel Nagy ◽  
Hume Stroud ◽  
Charalampia Koutsioumpa ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heterologous Gene Expression ◽  
High Specificity ◽  
Cell Types ◽  
Regulatory Elements ◽  
Cell Type ◽  
Cell Type Specificity ◽  
Cell Type Specific ◽  
The Many ◽  
Dna Regulatory Elements

Enhancers are the primary DNA regulatory elements that confer cell type specificity of gene expression. Recent studies characterizing individual enhancers have revealed their potential to direct heterologous gene expression in a highly cell-type-specific manner. However, it has not yet been possible to systematically identify and test the function of enhancers for each of the many cell types in an organism. We have developed PESCA, a scalable and generalizable method that leverages ATAC- and single-cell RNA-sequencing protocols, to characterize cell-type-specific enhancers that should enable genetic access and perturbation of gene function across mammalian cell types. Focusing on the highly heterogeneous mammalian cerebral cortex, we apply PESCA to find enhancers and generate viral reagents capable of accessing and manipulating a subset of somatostatin-expressing cortical interneurons with high specificity. This study demonstrates the utility of this platform for developing new cell-type-specific viral reagents, with significant implications for both basic and translational research.

scholarly journals SARS-CoV-2 infection and persistence throughout the human body and brain

2021 ◽  
Author(s):  
Daniel Chertow ◽  
Sydney Stein ◽  
Sabrina Ramelli ◽  
Alison Grazioli ◽  
Joon-Yong Chung ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Human Body ◽  
Symptom Onset ◽  
Acute Infection ◽  
Systemic Infection ◽  
The Body ◽  
Viral Clearance ◽  
Cell Type ◽  
Cell Type Specificity ◽  
The Brain

Abstract COVID-19 is known to cause multi-organ dysfunction1-3 in acute infection, with prolonged symptoms experienced by some patients, termed Post-Acute Sequelae of SARS-CoV-2 (PASC)4-5. However, the burden of infection outside the respiratory tract and time to viral clearance is not well characterized, particularly in the brain3,6-14. We performed complete autopsies on 44 patients with COVID-19 to map and quantify SARS-CoV-2 distribution, replication, and cell-type specificity across the human body, including brain, from acute infection through over seven months following symptom onset. We show that SARS-CoV-2 is widely distributed, even among patients who died with asymptomatic to mild COVID-19, and that virus replication is present in multiple extrapulmonary tissues early in infection. Further, we detected SARS-CoV-2 RNA in multiple anatomic sites, including regions throughout the brain, for up to 230 days following symptom onset. Despite extensive distribution of SARS-CoV-2 in the body, we observed a paucity of inflammation or direct viral cytopathology outside of the lungs. Our data prove that SARS-CoV-2 causes systemic infection and can persist in the body for months.

scholarly journals A Mixed-Surface Polyamidoamine Dendrimer for In Vitro and In Vivo Delivery of Large Plasmids

Pharmaceutics ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 619
Author(s):  
Bhairavi Srinageshwar ◽  
Maria Florendo ◽  
Brittany Clark ◽  
Kayla Johnson ◽  
Nikolas Munro ◽  
...  
Keyword(s):  
Viral Vectors ◽  
Viral Vector ◽  
Direct Injection ◽  
Gene Therapies ◽  
Large Plasmids ◽  
Surface Modified ◽  
The Brain ◽  
In Vivo Delivery

Drug delivery to the brain is highly hindered by the presence of the blood–brain barrier (BBB), which prevents the entry of many potential drugs/biomolecules into the brain. One of the current strategies to achieve gene therapy for neurodegenerative diseases involves direct injection of a viral vector into the brain. There are various disadvantages of viral vectors, including limitations of cargo size and safety concerns. Nanomolecules, such as dendrimers, serve as an excellent alternative to viral delivery. In this study, as proof-of-concept, we used a surface-modified dendrimer complex and delivered large plasmids to cells in vitro and in vivo in healthy rats via intracranial injection. The dendrimers were biodegradable by chemicals found within cells and toxicity assays revealed that the modified dendrimers were much less toxic than unmodified amine-surface dendrimers. As mentioned in our previous publication, these dendrimers with appropriately modified surfaces are safe, can deliver large plasmids to the brain, and can overcome the cargo size limitations associated with viral vectors. The biocompatibility of this dendritic nanomolecule and the ability to finely tune its surface chemistry provides a gene delivery system that could facilitate future in vivo cellular reprograming and other gene therapies.

scholarly journals Viral manipulation of functionally distinct neurons from mice to humans

2019 ◽  
Author(s):  
Douglas Vormstein-Schneider ◽  
Jessica Lin ◽  
Kenneth Pelkey ◽  
Ramesh Chittajallu ◽  
Baolin Guo ◽  
...  
Keyword(s):  
Regulatory Elements ◽  
Therapeutic Interventions ◽  
Cell Type ◽  
Adeno Associated Virus ◽  
Recent Success ◽  
Cortical Interneurons ◽  
Selective Targeting ◽  
Gene Regulatory Elements ◽  
Cell Type Specific ◽  
The Brain

Recent success in identifying gene regulatory elements in the context of recombinant adeno-associated virus vectors have enabled cell type-restricted gene expression. However, within the cerebral cortex these tools are presently limited to broad classes of neurons. To overcome this limitation, we developed a strategy that led to the identification of multiple novel enhancers to target functionally distinct neuronal subtypes. By investigating the regulatory landscape of the disease gene Scn1a, we identified enhancers that target the breadth of its expression, including two that are selective for parvalbumin and vasoactive intestinal peptide cortical interneurons. Demonstrating the functional utility of these elements, we found that the PV-specific enhancer allowed for the selective targeting and manipulation of these neurons across species, from mice to humans. Finally, we demonstrate that our selection method is generalizable to other genes and characterize four additional PV-specific enhancers with exquisite specificity for distinct regions of the brain. Altogether, these viral tools can be used for cell-type specific circuit manipulation and hold considerable promise for use in therapeutic interventions.

scholarly journals Systemic AAV6-synapsin-GFP administration results in lower liver biodistribution, compared to AAV1&2 and AAV9, with neuronal expression following ultrasound-mediated brain delivery

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Danielle Weber-Adrian ◽  
Rikke Hahn Kofoed ◽  
Joseph Silburt ◽  
Zeinab Noroozian ◽  
Kairavi Shah ◽  
...  
Keyword(s):  
Gene Delivery ◽  
Intravenous Injection ◽  
Viral Vectors ◽  
Focused Ultrasound ◽  
Fluorescent Protein ◽  
Gfp Expression ◽  
Peripheral Organs ◽  
Neuronal Expression ◽  
Green Fluorescent ◽  
The Brain

AbstractNon-surgical gene delivery to the brain can be achieved following intravenous injection of viral vectors coupled with transcranial MRI-guided focused ultrasound (MRIgFUS) to temporarily and locally permeabilize the blood–brain barrier. Vector and promoter selection can provide neuronal expression in the brain, while limiting biodistribution and expression in peripheral organs. To date, the biodistribution of adeno-associated viruses (AAVs) within peripheral organs had not been quantified following intravenous injection and MRIgFUS delivery to the brain. We evaluated the quantity of viral DNA from the serotypes AAV9, AAV6, and a mosaic AAV1&2, expressing green fluorescent protein (GFP) under the neuron-specific synapsin promoter (syn). AAVs were administered intravenously during MRIgFUS targeting to the striatum and hippocampus in mice. The syn promoter led to undetectable levels of GFP expression in peripheral organs. In the liver, the biodistribution of AAV9 and AAV1&2 was 12.9- and 4.4-fold higher, respectively, compared to AAV6. The percentage of GFP-positive neurons in the FUS-targeted areas of the brain was comparable for AAV6-syn-GFP and AAV1&2-syn-GFP. In summary, MRIgFUS-mediated gene delivery with AAV6-syn-GFP had lower off-target biodistribution in the liver compared to AAV9 and AAV1&2, while providing neuronal GFP expression in the striatum and hippocampus.

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