Introduction Lipoprotein(a) (Lp(a)) and oxidized LDL (oxLDL) are circulating lipoproteins known to promote development of atherosclerosis. LDL can be oxidized in several ways, including enzymatic oxidation by myeloperoxidase (MPO). The knowledge regarding these biomarkers in men and women with different presentations of peripheral arterial disease (PAD) is scarce. Aim To investigate sex differences in plasma levels of MPO, Lp(a) and oxLDL in patients undergoing open vascular surgery. A secondary aim was to elucidate how indication for surgery, risk factors and comorbidity influenced the levels of lipid markers. Methods A multicenter observational study done within the framework of an ongoing study targeting atherosclerosis, where lipids and inflammation are studied in patients undergoing open vascular surgery for either PAD (intermittent claudication (IC) or critical limb ischemia (CLI)) or carotid artery stenosis, having an ankle brachial pressure index <0.9 or >1.4. Participants were included 2019-2020, with blood samples collected immediately before surgery. Results A total of 30 men and 26 women were included. The indication for surgery was CLI (50.0%), IC (30.4%) and carotid stenosis (19.6%). Women and men displayed similar levels of Lp(a), MPO and oxLDL. Lp(a) was lower among CLI patients as compared to IC in univariate (P=0.038) but not in multivariate analysis. Oxidized LDL levels and LDL, Lp(a) and cholesterol correlated significantly. Conclusions There were no statistically significant differences in lipid markers between sexes. Levels of Lp(a) differed between the surgical indication groups and were lowest among the more severely diseased patients (CLI). Our findings need further evaluation in larger cohorts, taking effects of lipid-lowering therapies into consideration.

Multipotent mesenchymal stromal cells (MSC) have emerged as therapeutic tools for a wide range of pathological conditions. Yet, the still existing deficits regarding MSC phenotype characterization and the resulting heterogeneity of MSC used in different preclinical and clinical studies hamper the translational success. In search for novel MSC characterization approaches to complement the traditional trilineage differentiation and immunophenotyping assays reliably across species and culture conditions, this study explored the applicability of lipid phenotyping for MSC characterization and discrimination. Human peripheral blood mononuclear cells (PBMC), human fibroblasts, and human and equine adipose-derived MSC were used to compare different mesodermal cell types and MSC from different species. For MSC, cells cultured in different conditions, including medium supplementation with either fetal bovine serum or platelet lysate as well as culture on collagen-coated dishes, were additionally investigated. After cell harvest, lipids were extracted by chloroform/ methanol according to Bligh and Dyer. The lipid profiles were analysed by an untargeted approach using liquid chromatography coupled to mass spectrometry (LCMS) with a reversed phase column and an ion trap mass spectrometer. In all samples, phospholipids and sphingomyelins were found, while other lipids were not detected with the current approach. The phospholipids included different species of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS) in all cell types, whereas phosphatidylglycerol (PG) species were only present in MSC. MSC from both species showed a higher phospholipid species diversity than PBMC and fibroblasts. Few differences were found between MSC from different culture conditions, except that human MSC cultured with platelet lysate exhibited a unique phenotype in that they exclusively featured PE O-40:4, PG 38:6 and PG 40:6. In search for specific and inclusive candidate MSC lipid markers, we identified PE O-36:3 and PG 40:7 as potentially suitable markers across culture conditions, at which PE O-36:3 might even be used across species. On that basis, phospholipid phenotyping is a highly promising approach for MSC characterization, which might condone some heterogeneity within the MSC while still achieving a clear discrimination even from fibroblasts. Particularly the presence or absence of PG might emerge as a decisive criterion for future MSC characterization.