Evaluation of a method of preparation of lipid emulsions as a model for chylomicron-like particles.

Chylomicron remnants can penetrate into the artery wall, where they can initiate atherogenesis. Since it is difficult to isolate these particles from human blood because of contamination with other lipoproteins, the use of lipid emulsions as chylomicron remnant-like particles (CRLPs) has been proposed to study their metabolism. This study was aimed to evaluate the methodology for the preparation of CRLP. Artificial chylomicrons were prepared by sonication of a lipid mixture and separated by density gradient centrifugation. Lipid classes were analyzed by HPLC and fatty acids by GC. Particle size was measured by dynamic light scattering and the presence of apolipoprotein E by immunoblotting. The highest lipid content was found in the 60 < Sf < 400 fraction (Sf = Svedberg flotation rate), followed by the Sf > 400. This latter fraction presented the highest triacylglycerol (TAG) concentration, which was dramatically reduced in the 20 < Sf < 60 fraction. Fatty acid composition in TAG and phospholipids resembled that of the standards used with little modifications. The repeatability of the method was excellent, showing relative standard errors below 10%. The mean size of the 60 < Sf < 400 and Sf > 400 fractions, was 195.1 and 347.8 nm, respectively. The lipid analysis showed that Sf > 400 particles resembled the composition of natural chylomicrons and the 60 < Sf < 400 particles that of chylomicron remnants, the range of particle size being more homogeneous in the 60 < Sf < 400 fraction. The method mentioned in this article is not only a reliable method for the preparation of CRLP, but also for native chylomicron-like particles, in terms of lipid composition and particle size.