Endothelial cell response to bioactive peptides and stiffened extracellular matrices: an investigation into atherogenic pathways

Abstract

Endothelial dysfunction is the initiating step in atherosclerosis and leads to cardiovascular disease outcomes. This dysfunction can be mitigated by cardioprotective signaling molecules such as nitric oxide (NO) which can be upregulated in the presence of bioactive milk peptides. An investigation into the NO liberating capacity of select bioactive peptides was performed on cultures of Human Umbilical Vein Endothelial Cells (HUVECs) and two tripeptides (VPP and IPP) were found to liberate ~50% more NO. This finding drove a further investigation into whether endothelial cells grown on varying matrix stiffness would experience mechanical forces resulting in cellular responses more indicative of in vivo conditions. Polyacrylamide (PAC) gels of varying stiffness (2.5, 3, 10 and 30kPa) were prepared, and cell growth characteristics and inflammatory responses were measured over a nine day period. Findings showed that stiffer gels (10 and 30kPa) supported the growth of significantly higher numbers of HUVECs with smaller cell areas; however, gel stiffness did not induce a pro-inflammatory response in this cell line. Therefore, these results support PAC gels as useful in simulating a biologically relevant environment for the purposes of endothelial dysfunction investigations.