To realize the therapeutic potential of RNA drugs, efficient, tissue-specific and nonimmunogenic delivery technologies must be developed. Here we show that exosomes-endogenous nano-vesicles that ...transport RNAs and proteins-can deliver short interfering (si)RNA to the brain in mice. To reduce immunogenicity, we used self-derived dendritic cells for exosome production. Targeting was achieved by engineering the dendritic cells to express Lamp2b, an exosomal membrane protein, fused to the neuron-specific RVG peptide. Purified exosomes were loaded with exogenous siRNA by electroporation. Intravenously injected RVG-targeted exosomes delivered GAPDH siRNA specifically to neurons, microglia, oligodendrocytes in the brain, resulting in a specific gene knockdown. Pre-exposure to RVG exosomes did not attenuate knockdown, and non-specific uptake in other tissues was not observed. The therapeutic potential of exosome-mediated siRNA delivery was demonstrated by the strong mRNA (60%) and protein (62%) knockdown of BACE1, a therapeutic target in Alzheimer's disease, in wild-type mice.
The development of new therapies to slow down or halt the progression of Parkinson’s disease is a health care priority. A key pathological feature is the presence of alpha-synuclein aggregates, and ...there is increasing evidence that alpha-synuclein propagation plays a central role in disease progression. Consequently, the downregulation of alpha-synuclein is a potential therapeutic target. As a chronic disease, the ideal treatment will be minimally invasive and effective in the long-term. Knockdown of gene expression has clear potential, and siRNAs specific to alpha-synuclein have been designed; however, the efficacy of siRNA treatment is limited by its short-term efficacy. To combat this, we designed shRNA minicircles (shRNA-MCs), with the potential for prolonged effectiveness, and used RVG-exosomes as the vehicle for specific delivery into the brain. We optimized this system using transgenic mice expressing GFP and demonstrated its ability to downregulate GFP protein expression in the brain for up to 6 weeks. RVG-exosomes were used to deliver anti-alpha-synuclein shRNA-MC therapy to the alpha-synuclein preformed-fibril-induced model of parkinsonism. This therapy decreased alpha-synuclein aggregation, reduced the loss of dopaminergic neurons, and improved the clinical symptoms. Our results confirm the therapeutic potential of shRNA-MCs delivered by RVG-exosomes for long-term treatment of neurodegenerative diseases.
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This study demonstrated the potential of shRNA minicircles delivered by RVG-exosomes to induce the long-term downregulation of targeted genes in the brain. Izco and colleagues proved, using a parkinsonian mouse model, that this therapy can prevent the loss of dopaminergic neurons, decrease alpha-synuclein aggregates, and avoid the motor deficit.
Abstract Alpha-synuclein aggregation plays a central role in Parkinson's disease pathology. Direct transmission of alpha-synuclein from pathologically affected to healthy unaffected neurons may be ...important in the anatomical spread of the disease through the nervous system. We have demonstrated that exosomes released from alpha-synuclein over-expressing SH-SY5Y cells contained alpha-synuclein and these exosomes were capable of efficiently transferring alpha-synuclein protein to normal SH-SY5Y cells. Moreover, the incubation of cells with ammonium chloride or bafilomycin A1 to produce the lysosomal dysfunction recently reported in Parkinson's disease led to an increase in the release of alpha-synuclein in exosomes and a concomitant increase in alpha-synuclein transmission to recipient cells. This study clearly demonstrates the importance of exosomes in both the release of alpha synuclein and its transmission between cells and suggests that factors associated with PD pathology accelerate this process. These mechanisms may play an important role in PD pathology and provide a suitable target for therapeutic intervention.
The need to distribute therapy evenly systemically throughout the large muscle volume within the body makes Duchenne muscular dystrophy (DMD) therapy a challenge. Cell and exon-skipping therapies are ...promising but have limited effects, and thus enhancing their therapeutic potency is of paramount importance to increase the accessibility of these therapies to DMD patients. In this study, we demonstrate that co-administered glycine improves phosphorodiamidate morpholino oligomer (PMO) potency in mdx mice with marked functional improvement and an up to 50-fold increase of dystrophin in abdominal muscles compared to PMO in saline. Glycine boosts satellite cell proliferation and muscle regeneration by increasing activation of mammalian target of rapamycin complex 1 (mTORC1) and replenishing the one-carbon unit pool. The expanded regenerating myofiber population then results in increased PMO uptake. Glycine also augments the transplantation efficiency of exogenous satellite cells and primary myoblasts in mdx mice. Our data provide evidence that glycine enhances satellite cell proliferation, cell transplantation, and oligonucleotide efficacy in mdx mice, and thus it has therapeutic utility for cell therapy and drug delivery in muscle-wasting diseases.
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Yin and colleagues demonstrate that intravenous or dietary glycine enhances satellite cell proliferation, cell transplantation efficiency, and oligonucleotide-mediated dystrophin restoration in a Duchenne muscular dystrophy (DMD) mouse model, portending more efficacious cell and exon-skipping therapies for DMD.
Personalized immunotherapy utilizing cancer vaccines tailored to the tumors of individual patients holds promise for tumors with high genetic heterogeneity, potentially enabling eradication of the ...tumor in its entirety.
Here, we demonstrate a general strategy for biological nanovaccines that trigger tailored tumor-specific immune responses for hepatocellular carcinoma (HCC). Dendritic cell (DC)-derived exosomes (DEX) are painted with a HCC-targeting peptide (P47-P), an α-fetoprotein epitope (AFP212-A2) and a functional domain of high mobility group nucleosome-binding protein 1 (N1ND-N), an immunoadjuvant for DC recruitment and activation, via an exosomal anchor peptide to form a "trigger" DEX vaccine (DEX
).
DEX
specifically promoted recruitment, accumulation and activation of DCs in mice with orthotopic HCC tumor, resulting in enhanced cross-presentation of tumor neoantigens and de novo T cell response. DEX
elicited significant tumor retardation and tumor-specific immune responses in HCC mice with large tumor burdens. Importantly, tumor eradication was achieved in orthotopic HCC mice when antigenic AFP peptide was replaced with the full-length AFP (A) to form DEX
. Supplementation of Fms-related tyrosine kinase 3 ligand greatly augmented the antitumor immunity of DEX
by increasing immunological memory against tumor re-challenge in orthotopic HCC mice. Depletion of T cells, cross-presenting DCs and other innate immune cells abrogated the functionality of DEX
.
These findings demonstrate the capacity of universal DEX vaccines to induce tumor-specific immune responses by triggering an immune response tailored to the tumors of each individual, thus presenting a generalizable approach for personalized immunotherapy of HCC, by extension of other tumors, without the need to identify tumor antigens.
Extracellular vesicles (EVs) have emerged as important mediators of intercellular communication in a diverse range of biological processes. For future therapeutic applications and for EV biology ...research in general, understanding the in vivo fate of EVs is of utmost importance. Here we studied biodistribution of EVs in mice after systemic delivery. EVs were isolated from 3 different mouse cell sources, including dendritic cells (DCs) derived from bone marrow, and labelled with a near-infrared lipophilic dye. Xenotransplantation of EVs was further carried out for cross-species comparison. The reliability of the labelling technique was confirmed by sucrose gradient fractionation, organ perfusion and further supported by immunohistochemical staining using CD63-EGFP probed vesicles. While vesicles accumulated mainly in liver, spleen, gastrointestinal tract and lungs, differences related to EV cell origin were detected. EVs accumulated in the tumour tissue of tumour-bearing mice and, after introduction of the rabies virus glycoprotein-targeting moiety, they were found more readily in acetylcholine-receptor-rich organs. In addition, the route of administration and the dose of injected EVs influenced the biodistribution pattern. This is the first extensive biodistribution investigation of EVs comparing the impact of several different variables, the results of which have implications for the design and feasibility of therapeutic studies using EVs.
Clinical deployment of oligonucleotides requires delivery technologies that improve stability, target tissue accumulation and cellular internalization. Exosomes show potential as ideal delivery ...vehicles. However, an affordable generalizable system for efficient loading of oligonucleotides on exosomes remain lacking. Here, we identified an Exosomal Anchor DNA Aptamer (EAA) via SELEX against exosomes immobilized with our proprietary CP05 peptides. EAA shows high binding affinity to different exosomes and enables efficient loading of nucleic acid drugs on exosomes. Serum stability of thrombin inhibitor NU172 was prolonged by exosome-loading, resulting in increased blood flow after injury in vivo. Importantly, Duchenne Muscular Dystrophy PMO can be readily loaded on exosomes via EAA (EXO
EAA-PMO
). EXO
EAA-PMO
elicited significantly greater muscle cell uptake, tissue accumulation and dystrophin expression than PMO in vitro and in vivo. Systemic administration of EXO
EAA-PMO
elicited therapeutic levels of dystrophin restoration and functional improvements in
mdx
mice. Altogether, our study demonstrates that EAA enables efficient loading of different nucleic acid drugs on exosomes, thus providing an easy and generalizable strategy for loading nucleic acid therapeutics on exosomes.
Synopsis
This study identifies an exosome-binding DNA aptamer (Exosomal Anchor Aptamer—EAA) and demonstrates that EAA binds to exosomes of different origins effectively and enables efficient loading of different nucleic acid drugs on exosomes. This study provides an easy generalizable strategy for loading nucleic acid therapeutics on exosomes orthogonal to CD63-binding peptides, which are better suited for protein and peptide loading.
EAA showed high binding affinity to exosomes irrespective of origin.
EAA enabled loading of different nucleic acid drugs on exosomes, with thrombin DNA aptamer inhibitor NU172 loaded on exosomes extended the serum stability.
Duchenne Muscular Dystrophy (DMD) phosphorodiamidate morpholino oligomers (PMOs) were efficiently loaded on exosomes via EAA to form EXO
EAA-PMO
and systemic administration EXO
EAA-PMO
at low doses improved muscle function and pathologies in dystrophic mice.
This study identifies an exosome-binding DNA aptamer (Exosomal Anchor Aptamer - EAA) and demonstrates that EAA binds to exosomes of different origins effectively and enables efficient loading of different nucleic acid drugs on exosomes. This study provides an easy generalizable strategy for loading nucleic acid therapeutics on exosomes orthogonal to CD63-binding peptides, which are better suited for protein and peptide loading.
Carbohydrate-based infusion solutions are widely used in the clinic. Here we show that co-administration of phosphorodiamidate morpholino oligomers (PMOs) with glucose enhances exon-skipping activity ...in Duchenne muscular dystrophy (DMD) mdx mice. We identify a glucose-fructose (GF) formulation that potentiates PMO activity, completely corrects aberrant Dmd transcripts, restores dystrophin levels in skeletal muscles and achieves functional rescue without detectable toxicity. This activity is attributed to enhancement of GF-mediated PMO uptake in the muscle. We demonstrate that PMO cellular uptake is energy dependent, and that ATP from GF metabolism contributes to enhanced cellular uptake of PMO in the muscle. Collectively, we show that GF potentiates PMO activity by replenishing cellular energy stores under energy-deficient conditions in mdx mice. Our findings provide mechanistic insight into hexose-mediated oligonucleotide delivery and have important implications for the development of DMD exon-skipping therapy.
Induced splice modulation of pre-mRNAs shows promise to correct aberrant disease transcripts and restore functional protein and thus has therapeutic potential. Duchenne muscular dystrophy (DMD) ...results from mutations that disrupt the DMD gene open reading frame causing an absence of dystrophin protein. Antisense oligonucleotide (AO)-mediated exon skipping has been shown to restore functional dystrophin in mdx mice and DMD patients treated intramuscularly in two recent phase 1 clinical trials. Critical to the therapeutic success of AO-based treatment will be the ability to deliver AOs systemically to all affected tissues including the heart. Here, we report identification of a series of transduction peptides (Pip5) as AO conjugates for enhanced systemic and particularly cardiac delivery. One of the lead peptide-AO conjugates, Pip5e-AO, showed highly efficient exon skipping and dystrophin production in mdx mice with complete correction of the aberrant DMD transcript in heart, leading to >50% of the normal level of dystrophin in heart. Mechanistic studies indicated that the enhanced activity of Pip5e-phosphorodiamidate morpholino (PMO) is partly explained by more efficient nuclear delivery. Pip5 series derivatives therefore have significant potential for advancing the development of exon skipping therapies for DMD and may have application for enhanced cardiac delivery of other biotherapeutics.
Mirtrons, short hairpin pre-microRNA (miRNA) mimics directly produced by intronic splicing, have recently been identified and experimentally confirmed in invertebrates. While there is evidence to ...suggest several mammalian miRNAs have mirtron origins, this has yet to be experimentally demonstrated. Here, we characterize the biogenesis of mammalian mirtrons by ectopic expression of splicing-dependent mirtron precursors. The putative mirtrons hsa-miR-877, hsa-miR-1226 and mmu-miR-1224 were designed as introns within eGFP. Correct splicing and function of these sequences as introns was shown through eGFP fluorescence and RT-PCR, while all mirtrons suppressed perfectly complementary luciferase reporter targets to levels similar to that of corresponding independently expressed pre-miRNA controls. Splicing-deficient mutants and disruption of key steps in miRNA biogenesis demonstrated that mirtron-mediated gene knockdown was splicing-dependent, Drosha-independent and had variable dependence on RNAi pathway elements following pre-miRNA formation. The silencing effect of hsa-miR-877 was further demonstrated to be mediated by the generation of short anti-sense RNA species expressed with low abundance. Finally, the mammalian mirtron hsa-miR-877 was shown to reduce mRNA levels of an endogenous transcript containing hsa-miR-877 target sites in neuronal SH-SY5Y cells. This work confirms the mirtron origins of three mammalian miRNAs and suggests that they are a functional class of splicing-dependent miRNAs which are physiologically active.
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