Exosome-Mediated Transfer of X-Motif-Tagged Anti-MiR-33a-5p Antagomirs to the Medial Cells of Transduced Rabbit Carotid Arteries

Abstract

Atherosclerosis is caused by the accumulation of cholesterol within intimal smooth muscle cells (SMCs) and macrophages. However, the transporter ATP-binding cassette subfamily A, member 1 (ABCA1), can remove cholesterol from these intimal, cells reducing atherosclerosis. Antagomir-mediated inhibition of miR-33a-5p, a microRNA that represses ABCA1 translation, promotes ABCA1-dependent cholesterol efflux and may impede atherosclerosis development. In our previous work, transducing cultured endothelial cells (ECs) with a helper-dependent adenoviral vector (HDAd) that expresses X-motif-tagged anti-miR-33a-5p enhanced antagomir packaging into EC-derived exosomes, which delivered the antagomir to cultured SMCs and macrophages. In this present study, we tested whether in vivo transduction of rabbit carotid artery endothelium can deliver an X-motif-tagged anti-miR-33a-5p to subendothelial cells. Rabbit carotid endothelial cells were transduced in vivo with an HDAd expressing anti-miR-33a-5p either with or without the X-motif (n = 11 arteries per vector). Contralateral carotids received HDAd that express scrambled oligonucleotides. Three days after transduction, the antagomir—without the X-motif—was detected in the intima but not in the media of transduced carotids (p = 0.062). The X-motif antagomir was detected in 82% of the intimal extracts (9 out of 11 carotids) and 27% of medial samples (3 out of 11 carotids, p = 0.031). However, the X-motif did not significantly enhance antagomir delivery to the media (p = 0.214 vs. non-X-motif antagomir). Expression of the antagomirs—with and without the X-motif—was sub-stoichiometric in ECs and SMCs. No antagomir-related changes in miR-33a-5p or ABCA1 expressions were detected. Despite its potential as a therapeutic strategy, our exosome-targeted gene transfer system requires further improvements to enhance antagomir expression and delivery to the subendothelial cells.

Keywords

• antagomir
• X-motif
• exosome
• MiR-33a-5p
• ABCA1
• vascular