BACKGROUND: Thoracic aortic aneurysm is a chronic disease characterized by localized dilation of the vessel, including the ascending, arch and descending parts of the aorta. Aneurysm is one of the most dangerous diseases because aortic dissection or rupture can lead to sudden death. More than 150,000 people worldwide die from aortic aneurysms every year. Despite its prevalence, the cellular mechanisms of its development remain not fully understood. AIM: To evaluate phagocytic activity and proinflammatory activation capability of smooth muscle cells isolated from tunica intima and tunica media of the thoracic part of the human aorta in patients with aneurysm. MATERIALS AND METHODS: The experiments were performed on a culture of primary smooth muscle cells isolated from aneurysm patients. Linear cultures (mesenchymal stem cells ASC52telo, fibroblasts 977hTERT, THP-1, CLTH-CL05008 and EA.hy926) and smooth muscle cells isolated from healthy donors were used as controls. Phagocytic activity was assessed by introducing latex beads to the studied cells, while the ability to internalize low-density lipoprotein was evaluated using the dye BDP 630/650 (Lumiprobe, Russia) and a biochemical method. Pro- and anti-inflammatory activation capability were measured using enzyme-linked immunosorbent assay, quantifying the secretion of cytokines, namely IL-8, IL-6 and IL-10. RESULTS: The study showed that the smooth cells have high phagocytic activity and the ability to internalize low-density lipoprotein. Thus, primary smooth muscle cells from tunica media have greater phagocytic activity than smooth muscle cells obtained from healthy donors (p 0.001). In addition, IL-6 secretion after incubation with latex beads was significantly higher in smooth muscle cells from tunica media compared to those from healthy donors (p 0.001). IL-6 secretion also increased after incubation with low-density lipoprotein in smooth muscle cells from tunica intima compared to cells from healthy donors (p 0.001). CONCLUSION: The absorption of latex beads and low-density lipoprotein stimulates the secretion of proinflammatory IL-6 by primary smooth muscle cells from tunica intima and smooth muscle cells from tunica media, which are part of the aortic wall of patients with aneurysm.

Endothelial dysfunction is an early event in the development of cardiovascular diseases and is characterized by impaired barrier function, inflammatory activation of endothelial cells (ECs), and alterations in lipid metabolism. In addition to typical (mononuclear) endothelial cells (TECs), multinucleated variant endothelial cells (MVECs) are present within the vascular wall; however, their functional role remains poorly understood. The aim of the present study was to investigate the molecular and functional characteristics of MVECs and their potential contribution to the development of endothelial dysfunction. Primary human umbilical vein endothelial cells (HUVECs) were used, and multinucleated cells were generated by polyethylene glycol-induced fusion. Cells were incubated under control conditions or exposed to low-density lipoproteins (LDL; 100 µg/mL, 24 h). A comprehensive analysis was performed, including transcriptomic and proteomic (secretome) profiling using gene set enrichment analysis (GSEA), as well as functional assays assessing transendothelial LDL transport, intracellular cholesterol accumulation, macrophage migration, and the expression and secretion of pro-inflammatory cytokines (IL-6, IL-8). MVECs exhibited pronounced differences compared to TECs. GSEA revealed reduced enrichment of pathways related to canonical nuclear factor kappa B (NF-κB) signaling and negative regulation of NF-κB transcription factor activity, actin cytoskeleton organization, focal adhesion assembly, basement membrane organization, and vesicle-mediated transport in MVECs relative to TECs, indicating impaired cytoskeletal integrity, altered cell–matrix interactions, dysregulated inflammatory signaling, and reduced vesicular trafficking activity. Functionally, MVECs demonstrated an increased capacity for cholesterol accumulation and enhanced transendothelial migration of macrophages. Notably, transendothelial LDL transport across the MVEC monolayer was not increased, suggesting a predominance of intracellular lipid accumulation. MVECs also exhibited a pronounced pro-inflammatory phenotype, characterized by elevated expression and secretion of IL-6 and IL-8. Taken together, these findings indicate that MVECs represent a functionally altered endothelial phenotype with impaired barrier function, dysregulated lipid metabolism, and enhanced inflammatory activity. Local accumulation of MVECs within the vascular wall may contribute to the formation of pro-atherogenic regions and play a role in the initiation and progression of endothelial dysfunction.