Lipid droplets (LDs) are dynamic organelles involved in intracellular lipid metabolism, and the biogenesis of LDs in endothelium is triggered by the excess of lipids in the environment. In this paper we present the methodology aimed to define the composition of endothelial LDs formed upon stimulation with oleic acid (OA) in two models: endothelial cells cultured in vitro and in isolated blood vessel ex vivo. The biochemical composition of LDs was determined using Raman imaging, followed by the lipid unsaturation calibration analysis and modelling of spectral bands based on individual spectra of selected lipids. Among LDs formed in response to OA in vitro or ex vivo conditions there were two types of LDs; those with more unsaturated (average number of CC bonds equalled 1.40) or saturated (average number of CC bonds equalled 0.95) lipids. The modelling of endothelial LDs composition revealed the OA represented a major component of LDs (80.6–91.3%) with an important content of arachidonic acid (8.7–19.4%). In conclusion, endothelial LDs consist of exogenous oleic acid uptaken from the extracellular space, and the endogenous arachidonic acid released from plasma membranes.

脂质滴（LDs）是参与细胞内脂质代谢的动态细胞器，内皮中LDs的生物发生是由环境中过多的脂质触发的。在本文中，我们介绍了两种方法来定义由油酸（OA）刺激后形成的内皮LD的组成：体外培养的内皮细胞和离体离体血管。LD的生化组成使用拉曼成像确定，然后进行脂质不饱和度校准分析，并根据所选脂质的各个光谱对光谱带进行建模。在体外或离体对OA响应而形成的LD中条件有两种类型的LD；那些具有更高的不饱和脂质（C C键的平均数等于1.40）或饱和（C C键的平均数等于0.95）脂质。内皮LDs组成的模型显示，OA代表了LDs的主要成分（80.6–91.3％），其中花生四烯酸的含量很高（8.7–19.4％）。总之，内皮细胞LDs由细胞外空间摄取的外源油酸和质膜释放的内源花生四烯酸组成。