Modification of small interfering RNAs to prevent off-target effects by the sense strand

N Biotechnol. 2013 Jan 25;30(2):159-65. doi: 10.1016/j.nbt.2012.10.001. Epub 2012 Nov 1.


Objective: There is a broad therapeutic potential for the application of small interfering RNAs (siRNAs). However, one has to ensure that siRNAs act specifically, only targeting the expression of one gene. Off-target effects raised by the sense strand have to be eliminated.

Methods and results: We examined a particular bidirectional siRNA molecule, able to knockdown intercellular adhesion molecule-1 (ICAM-1) and tumor necrosis factor receptor-1 (TNFR-1) by the sense or antisense strand, respectively. Transfection of human venous endothelial cells with an unmodified siRNA molecule led to equal silencing of ICAM-1 and TNFR-1. In contrast, modified siRNA was able to knockdown ICAM-1 and TNFR-1 separately, with only the antisense strand.

Discussion: We found the modified siRNAs to inhibit off-target effects originated by the sense strand. Our approach demonstrates one possibility to modify siRNAs before starting a clinical approach to eliminate off-target effects.

MeSH terms

  • Codon / genetics*
  • E-Selectin / metabolism
  • Endothelial Cells / cytology
  • Endothelial Cells / metabolism
  • Humans
  • Intercellular Adhesion Molecule-1 / metabolism
  • Models, Biological
  • RNA, Small Interfering / metabolism*
  • Receptors, Tumor Necrosis Factor, Type I / metabolism
  • Transfection
  • Tumor Necrosis Factor-alpha / metabolism
  • Vascular Cell Adhesion Molecule-1 / metabolism


  • Codon
  • E-Selectin
  • RNA, Small Interfering
  • Receptors, Tumor Necrosis Factor, Type I
  • Tumor Necrosis Factor-alpha
  • Vascular Cell Adhesion Molecule-1
  • Intercellular Adhesion Molecule-1