The clinical use of CRISPR-Cas9, siRNA or antisense oligonucleotides (ASOs) has been hampered by the body’s defence systems and a lack of bioavailability. Recent successes transferring mRNA to muscle cells for RNA vaccines and licensed siRNA drugs that operate in the liver give us cause for hope. However, the immune system and drug compartmentalisation at the gross and sub-cellular level result in vastly reduced drug bioavailability.1,2&3
We have protected technologies that utilise exosome-mediated4 modulators of subcellular compartmentalisation. These technologies utilise protein domains which have evolved to access the nucleocytosolic compartment via intraluminal vesicles (ILVs). Consequently, they do not exhibit measurable toxicity when delivering their cargo. As ILVs are exosome precursors, our technology can be used to load exosomes. Exosomes are small (30-300nm) cell derived liposome-like structures which carry both nucleic acids and proteins from the nucleocytosolic compartment of one cell to that of another, evading the immune system and destruction by lysosomal hydrolases.
Our exosome-mediated delivery strategy deploys non-toxic recombinant proteins to deliver macromolecular cargo to the ILVs of donor cells. The cargo is chased into ILVs and their secretion as exosomes is induced. The cargo-containing exosomes are isolated, characterised and used to deliver siRNA or other large molecules to recipient cells.4 The rationale behind the exosome-mediated delivery system may make it possible to load macromolecular drugs into patient cells further minimising the potential for adverse patient reactions.
(1) Delivery of siRNA to somatic cells for the modulation of gene expression
(2) Delivery of ASOs to somatic cells for the modulation of gene expression
(1) Juliano, R. L., et al., (2012). Cellular Uptake and Intracellular Trafficking of Antisense and siRNA Oligonucleotides. Bioconjugate Chem., 23(2), 147–157. http://doi.org/10.1021/bc200377d;
(2) Merkel, O. M., & Kissel, T. (2014). Quo vadis polyplex? Journal of Controlled Release, 190, 415–423. http://doi.org/10.1016/j.jconrel.2014.06.009;
(3) Guo, S., & Huang, L. (2011). Nanoparticles Escaping RES and Endosome: Challenges for siRNA Delivery for Cancer Therapy. Journal of Nanomaterials, 12: 1–12. http://doi.org/10.1155/2011/742895;
(4) https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2020030923
© Copyright 2020. All Rights Reserved.