Effects of WSCM, eVCM and Nicotine on monocyte adhesion to human aortic endothelial cells

Atherosclerosis is a complex process involving progressive pathological events, including monocyte adhesion to the luminal endothelial surface. We have developed a functional in vitro adhesion assay using BioFlux™ microfluidic technology to investigate THP-1 human monocyte adhesion to human aortic endothelial cells (HAECs).

Here, we evaluated the effects of whole smoke conditioned media (WSCM) generated from University of Kentucky reference cigarette 3R4F, electronic cigarette vapor conditioned media (eVCM) from an electronic nicotine delivery system (ENDS) product (Vype ePen), and nicotine (NIC). HAEC monolayers were grown in microfluidic channels and exposed to 0–3000 ng/mL nicotine, or 0–3000 ng/mL nicotine equivalence of WSCM or eVCM for 24 hours. Activated THP-1 cells were perfused through the microfluidic channels and left to adhere under static conditions. The perfusion, adhesion period and wash cycle was performed four times with increasing adhesion periods (10, 20, 30 and 40 minutes). THP-1 cell numbers were quantified by counting adherent cells from three fields of view.

WSCM and eVCM induced dose-dependent increases in THP-1 cell adhesion of up to 3-fold and 2-fold, respectively, compared with control. Adhesion regulation was linked to increases in ICAM-1 protein expression. Co-localization staining of ICAM-1 in HAECs and cd11b (MAC-1) in THP-1 cells demonstrated adhesion molecule interaction in BioFlux™ microfluidic plates. We conclude that the BioFlux™ system and associated devices are able to model human monocyte adhesion to human endothelial cells in vitro and that WSCM drove the greatest increases in both adhesion and endothelial expression of ICAM-1.