hMSC adhere to murine carotid arteries. (A) hMSCs labelled with a cell tracker were adoptively transferred into Apoe^−/− mice fed with high-fat diet for 4 weeks and interactions with the arterial endothelium of the carotid artery was visualized by epifluorescence microscopy (white arrows). (B) Carotid arteries were explanted from Apoe^–/– mice fed with high-fat diet. A 1:1 mixture of red and green labelled hMSCs transfected with let-7f mimics or non-specific oligonucleotide control were perfused through the mounted vessel. Adherent hMSCs were detected in randomly selected areas and analysed using two-photon laser scanning microscopy. Scale bars: 100 µm (en face view) and 10 µm (side view). (C) Quantification of the ex vivo adhesion assay. The Forest plot shows the adhesion index of let-7f-transfected hMSCs (ratio of adherent let-7f-transfected to control siRNA-transfected hMSCs) perfused in mounted carotid arteries of Apoe^−/− (n = 5) and wildtype mice (WT) (n = 2). Results were collected in 8 different fields of view per mouse (n = 40 in Apoe^–/– and n = 16 in WT mice). P-values computed by Wilcoxon signed-rank test (C). n.s., not significant.