Functional features of smooth muscle cells of the human aortic wall and their role in the pathogenesis of aneurysms

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.