Efficiency of siRNA delivery by lipid nanoparticles is limited by endocytic recycling

Nat Biotechnol. 2013 Jul;31(7):653-8. doi: 10.1038/nbt.2614. Epub 2013 Jun 23.

Abstract

Despite efforts to understand the interactions between nanoparticles and cells, the cellular processes that determine the efficiency of intracellular drug delivery remain unclear. Here we examine cellular uptake of short interfering RNA (siRNA) delivered in lipid nanoparticles (LNPs) using cellular trafficking probes in combination with automated high-throughput confocal microscopy. We also employed defined perturbations of cellular pathways paired with systems biology approaches to uncover protein-protein and protein-small molecule interactions. We show that multiple cell signaling effectors are required for initial cellular entry of LNPs through macropinocytosis, including proton pumps, mTOR and cathepsins. siRNA delivery is substantially reduced as ≅70% of the internalized siRNA undergoes exocytosis through egress of LNPs from late endosomes/lysosomes. Niemann-Pick type C1 (NPC1) is shown to be an important regulator of the major recycling pathways of LNP-delivered siRNAs. NPC1-deficient cells show enhanced cellular retention of LNPs inside late endosomes and lysosomes, and increased gene silencing of the target gene. Our data suggest that siRNA delivery efficiency might be improved by designing delivery vehicles that can escape the recycling pathways.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Carrier Proteins
  • Endocytosis / genetics*
  • Gene Silencing
  • Gene Transfer Techniques
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Lipids / administration & dosage*
  • Lipids / chemistry
  • Lipids / genetics
  • Membrane Glycoproteins
  • Metal Nanoparticles / administration & dosage*
  • Metal Nanoparticles / chemistry
  • Microscopy, Confocal
  • RNA, Small Interfering / administration & dosage*
  • RNA, Small Interfering / chemistry
  • RNA, Small Interfering / genetics
  • Signal Transduction / genetics
  • TOR Serine-Threonine Kinases / genetics
  • TOR Serine-Threonine Kinases / metabolism

Substances

  • Carrier Proteins
  • Intracellular Signaling Peptides and Proteins
  • Lipids
  • Membrane Glycoproteins
  • NPC1 protein, human
  • RNA, Small Interfering
  • MTOR protein, human
  • TOR Serine-Threonine Kinases