Novel endosomolytic compounds enable highly potent delivery of antisense oligonucleotides

Commun Biol. 2022 Mar 1;5(1):185. doi: 10.1038/s42003-022-03132-2.


The therapeutic and research potentials of oligonucleotides (ONs) have been hampered in part by their inability to effectively escape endosomal compartments to reach their cytosolic and nuclear targets. Splice-switching ONs (SSOs) can be used with endosomolytic small molecule compounds to increase functional delivery. So far, development of these compounds has been hindered by a lack of high-resolution methods that can correlate SSO trafficking with SSO activity. Here we present in-depth characterization of two novel endosomolytic compounds by using a combination of microscopic and functional assays with high spatiotemporal resolution. This system allows the visualization of SSO trafficking, evaluation of endosomal membrane rupture, and quantitates SSO functional activity on a protein level in the presence of endosomolytic compounds. We confirm that the leakage of SSO into the cytosol occurs in parallel with the physical engorgement of LAMP1-positive late endosomes and lysosomes. We conclude that the new compounds interfere with SSO trafficking to the LAMP1-positive endosomal compartments while inducing endosomal membrane rupture and concurrent ON escape into the cytosol. The efficacy of these compounds advocates their use as novel, potent, and quick-acting transfection reagents for antisense ONs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Endosomes / metabolism
  • Intracellular Membranes
  • Lysosomes
  • Oligonucleotides* / metabolism
  • Oligonucleotides, Antisense* / genetics
  • Oligonucleotides, Antisense* / pharmacology


  • Oligonucleotides
  • Oligonucleotides, Antisense