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Glioma-targeted delivery of exosome-encapsulated antisense oligonucleotides using neural stem cells.

ABSTRACT: Tropism of neural stem cells (NSCs) to hypoxic tumor areas provides an opportunity for the drug delivery. Here, we demonstrate that NSCs effectively transport antisense oligonucleotides (ASOs) targeting oncogenic and tolerogenic signal transducer and activator of transcription 3 (STAT3) protein into glioma microenvironment. To enable spontaneous, scavenger receptor-mediated endocytosis by NSCs, we used previously described CpG-STAT3ASO conjugates. Following uptake and endosomal escape, CpG-STAT3ASO colocalized with CD63⁺ vesicles and later with CD63⁺CD81⁺ exosomes. Over 3 days, NSCs secreted exosomes loaded up to 80% with CpG-STAT3ASO. Compared to native NSC exosomes, the CpG-STAT3ASO-loaded exosomes potently stimulated immune activity of human dendritic cells or mouse macrophages, inducing nuclear factor κB (NF-κB) signaling and interleukin-12 (IL-12) production. Using orthotopic GL261 tumors, we confirmed that NSC-mediated delivery improved oligonucleotide transfer from a distant injection site into the glioma microenvironment versus naked oligonucleotides. Correspondingly, the NSC-delivered CpG-STAT3ASO enhanced activation of glioma-associated microglia. Finally, we demonstrated that NSC-mediated CpG-STAT3ASO delivery resulted in enhanced antitumor effects against GL261 glioma in mice. Peritumoral injections of 5 × 10⁵ NSCs loaded ex vivo with CpG-STAT3ASO inhibited subcutaneous tumor growth more effectively than the equivalent amount of oligonucleotide alone. Based on these results, we anticipate that NSCs and NSC-derived exosomes will provide a clinically relevant strategy to improve delivery and safety of oligonucleotide therapeutics for glioma treatment.

SUBMITTER: Adamus T

PROVIDER: S-EPMC8752899 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Synthetic nucleic acids have shown great potential in the treatment of various diseases. Nevertheless, the selective delivery to a target tissue has proved challenging. The coupling of nucleic acids to targeting peptides, proteins, and antibodies has been explored as an approach for their selective tissue delivery. Nevertheless, the preparation of covalently coupled peptides and proteins that can also undergo intracellular release as well as deliver more than one copy of the nucleic acid has proved challenging. Recently, we have developed a novel method for the rapid noncovalent conjugation of nucleic acids to targeting single chain antibodies (scFv) using chemically self-assembled nanostructures (CSANs). CSANs have been prepared by the self-assembly of two dihydrofolate reductase molecules (DHFR(2)) and a targeting scFv in the presence of bis-methotrexate (bis-MTX). The valency of the nanorings can be tuned from one to eight subunits, depending on the length and composition of the linker between the dihydrofolate reductase molecules. To explore their potential for the therapeutic delivery of nucleic acids as well as the ability to expand the capabilities of CSANs by incorporating smaller cyclic targeting peptides, we prepared DHFR(2) proteins fused through a flexible peptide linker to cyclic-RGD, which targets ?v?3 integrins, and a bis-MTX chemical dimerizer linked to an antisense oligonucleotide (bis-MTX-ASO) that has been shown to silence expression of eukaryotic translation initiation factor 4E (eIF4E). Monomeric and multimeric cRGD-CSANs were then prepared with bis-MTX-ASO and shown to undergo endocytosis in the breast cancer cell line, MDA-MB-231, which overexpresses ?v?3. The bis-MTX-ASO was shown to undergo endosomal escape resulting in the knock down of eIF4E with at least the same efficiency as ASO delivered by oligofectamine. The modularity, flexibility, and common method of conjugation may prove to be a useful general approach for the targeted delivery of ASOs, as well as other nucleic acids to cells.

Project description:Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease affecting the upper and lower motor neurons in the motor cortex and spinal cord. Abnormal accumulation of mutant superoxide dismutase I (SOD1) in motor neurons is a pathological hallmark of some forms of the disease. We have shown that the orderly progression of the disease may be explained by misfolded SOD1 cell-to-cell propagation, which is reliant upon its active endogenous synthesis. Reducing the levels of SOD1 is therefore a promising therapeutic approach. Antisense oligonucleotides (ASOs) can efficiently silence proteins with gain-of-function mutations. However, naked ASOs have a short circulation half-life and are unable to cross the blood brain barrier (BBB) warranting the use of a drug carrier for effective delivery. In this study, calcium phosphate lipid coated nanoparticles (CaP-lipid NPs) were developed for delivery of SOD1 ASO to motor neurons. The most promising nanoparticle formulation (Ca/P ratio of 100:1), had a uniform spherical core-shell morphology with an average size of 30 nm, and surface charge (ζ-potential) of -4.86 mV. The encapsulation efficiency of ASO was 48% and stability studies found the particle to be stable over a period of 20 days. In vitro experiments demonstrated that the negatively charged ASO-loaded CaP-lipid NPs could effectively deliver SOD1-targeted ASO into a mouse motor neuron-like cell line (NSC-34) through endocytosis and significantly down-regulated SOD1 expression in HEK293 cells. The CaP-lipid NPs exhibited a pH-dependant dissociation, suggesting that that the acidification of lysosomes is the likely mechanism responsible for facilitating intracellular ASO release. To demonstrate tissue specific delivery and localization of these NPs we performed in vivo microinjections into zebrafish. Successful delivery of these NPs was confirmed for the zebrafish brain, the blood stream, and the spinal cord. These results suggest that CaP-lipid NPs could be an effective and safe delivery system for the improved delivery of SOD1 ASOs to motor neurons. Further in vivo evaluation in transgenic mouse models of SOD1 ALS are therefore warranted.

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Glioma-targeted delivery of exosome-encapsulated antisense oligonucleotides using neural stem cells.

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