Rhodamine-labeled LDL as a tool to monitor the lipoprotein traffic in experimental model of early atherosclerosis in mice

Modifications of proteoglycans, subendothelial retention of low-density lipoproteins (LDL) and their subsequent oxidation initiate the development of atherosclerosis. Therefore, detection of lipoprotein entrapment in the arterial wall is an important feature for the analysis of the mechanisms of atherosclerosis. The administration of fluorescent-labeled LDL in vivo is a breakthrough way to assess the traffic of LDL in the arterial wall. The present study demonstrated the feasibility of visualizing LDL in carotid ligation-induced intimal thickening of arterial wall after intravenous rhodamine-labeled LDL injection in mice. Kinetics of rhodamine-labeled LDL showed similar characteristics as native LDL and labeled-LDL could be detected both by spectrophotometric and microscopic analysis. Kinetics analysis of rhodamine-labeled LDL revealed that the labeled LDL was present in almost all tissue, predominantly in the liver, 6 hours after injection. Rhodamine-labeled LDL was visualized in intimal thickening of carotid 6 to 18 hours after injection, indicating that the LDL was actively trapped in the arterial wall. In conclusion, rhodamine-labeled LDL would be a useful tool to investigate the development of atherosclerosis.