Using different endothelial/smooth muscle cell co-culture modes to simulate the intimal structure of blood vessels, the water filtration rate and the infiltration/accumulation of LDL of the cultured cell layers were studied. The three cell culture modes of the study were: (i) The endothelial cell monolayer (EC/Φ); (ii) endothelial cells directly co-cultured on the smooth muscle cell monolayer (EC-SMC); (iii) endothelial cells and smooth muscle cells cultured on different sides of a Millicell-CM membrane (EC/SMC). It was found that under the same condition, the water filtration rate was the lowest for the EC/SMC mode and the highest for the EC/Φ mode, while the infiltration/accumulation of DiI-LDLs was the lowest in the EC/Φ mode and the highest in the EC-SMC mode. It was also found that DiI-LDL infiltration/accumulation in the cultured cell layers increased with the increasing water filtration rate. The results from the in vitro model study therefore suggest that the infiltration/accumulation of the lipids within the arterial wall is positively correlated with concentration polarization of atherogenic lipids, and the integrity of the endothelium plays an important role in the penetration and accumulation of atherogenic lipids in blood vessel walls.
DING ZuFeng, FAN YuBo & DENG XiaoYan School of Biological Science & Medical Engineering, Beihang University, Beijing 100191, China
To verify the previous theoretical prediction that the disturbed flow distal to a stenosis enhances lipid accumulation at the blood/arterial wall interface, we designed a canine carotid arterial stenosis model and measured ex vitro the luminal surface concentration of bovine serum albumin (as a tracer mac-romolecule) by directly taking liquid samples from the luminal surface of the artery. The experimental results showed that due to the presence of a filtration flow, the luminal surface albumin concentration cw was higher than the bulk concentration co as predicted by our theory. The measurement revealed that the luminal surface concentration of macromolecules was indeed enhanced significantly in re-gions of the disturbed flow. At Re = 50, the relative luminal surface concentration cw/co was 1.66 ± 0.10 in the vortex region, while the cw/co was 1.37 ± 0.06 in the laminar flow region. When Re increased to 100, the cw/co in the vortex flow region and the laminar flow region reduced to 1.39 ± 0.07 and 1.24 ± 0.04, respectively. The effect of the filtration rate, vw, on the luminal surface concentration of albumin was remarkably apparent. At Re = 50 and 100, when vw = 8.9 ± 1.7 × 10-6 cm/s, cw in the vortex region was 77% and 52% higher than co respectively, meanwhile when vw = 4.8 ± 0.6 × 10-6 cm/s, cw in the vortex region was only 66 % and 39% higher than co respectively. In summary, the present study has provided further experimental evidence that concentration polarization can occur in the arterial system and fluid layer with highly concentrated lipids in the area of flow separation point may be responsible for the formation and development of atherosclerosis.
ZHANG ZhiGuo1, DENG XiaoYan1,2, FAN YuBo2 & LI DeYu 2 1 State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116023, China
