Comparison of lipoprotein separation and lipid analysis methodologies for human and cynomolgus monkey plasma samples

To assess cardiovascular risk in both clinical and basic research settings, it is imperative to be able to accurately measure plasma lipid levels. Here, methods commonly used to measure lipoproteins and lipids: ultracentrifugation (UC), fast protein liquid chromatography (FPLC), Roche auto-analyzer, and enzymatic assays were tested and compared. Plasma samples from 20 healthy humans and 22 cynomolgus monkeys were analyzed for their total cholesterol (TC), cholesterol in low density lipoproteins (LDL) and high density lipoproteins (HDL), and triglycerides (TG). Major lipid classes from UC and FPLC separated lipoprotein fractions from human plasma were further characterized by liquid chromatography-mass spectrometry analysis. All the tested methods showed acceptable performance with Roche analyzer among the best in approximate dilution linearity and recovery for most lipids as well as in repeatability between measurements of the same samples. TC, LDL, HDL, and TG values measured in human vs. monkey were-183.9 ± 35.5 (mean ± SD) vs. 105.6 ± 24.6 mg/dl, 106.0 ± 30.1 vs. 42.8 ± 13.0 mg/dl, 50.0 ± 11.4 vs. 53.4 ± 14.8 mg/dl, and 107.6 ± 50.7 vs. 58.0 ± 52.3 mg/dl. While no single method was uniformly the best, we recommend the Roche analyzer for routine measurements. UC or FPLC separation is needed for further functional characterization for specific lipid fraction. We have shown athero-protective profile in cynomolgus monkey compared with humans.