Cultures of proliferating vascular smooth muscle cells from adult human aorta

Pers reverse angiotensin II -induced vascular smooth muscle cell proliferation by targeting cyclin E expression via inhibition of the MAPK signaling pathway

The circadian rhythm of blood pressure (BP) is believed to be regulated by the clock system, which is closely linked to levels of angiotensin II (Ang II). This study aimed to investigate whether Ang II mediates the proliferation of vascular smooth muscle cells (VSMCs) through the interaction between the clock system and the mitogen-activated protein kinase (MAPK) signaling pathway. Primary rat aortic VSMCs were treated with Ang II, with or without MAPK inhibitors. VSMC proliferation, expression of clock genes, CYCLIN E, and MAPK pathways were assessed. Ang II treatment resulted in increased VSMC proliferation and rapid upregulation of clock gene Periods (Pers) expression. Compared to the non-diseased control (NC) group, VSMCs incubated with Ang II displayed a noticeable delay in the G1/S phase transition and downregulation of CYCLIN E upon silencing of Per1 and Per2 genes. Importantly, silencing Per1 or Per2 in VSMCs led to decreased expression of key MAPK pathway proteins, including RAS, phosphorylated mitogen-activated protein kinase (P-MEK), and phosphorylated extracellular signal-regulated protein kinase (P-ERK). Moreover, the MEK and ERK inhibitors, U0126 and SCH772986, significantly attenuated the Ang II-induced proliferation of VSMCs, as evidenced by an increased G1/S phase transition and decreased CYCLIN E expression. The MAPK pathway plays a critical role in regulating VSMC proliferation in response to Ang II stimulation. This regulation is controlled by the expression of circadian clock genes involved in the cell cycle. These findings provide novel insights for further research on diseases associated with abnormal VSMC proliferation.

BCL6 Attenuates Proliferation and Oxidative Stress of Vascular Smooth Muscle Cells in Hypertension

Proliferation and oxidative stress of vascular smooth muscle cells (VSMCs) contribute to vascular remodeling in hypertension and several major vascular diseases. B-cell lymphoma 6 (BCL6) functions as a transcriptional repressor. The present study is designed to determine the roles of BCL6 in VSMC proliferation and oxidative stress and underlying mechanism. Angiotensin (Ang) II was used to induce VSMC proliferation and oxidative stress in human VSMCs. Effects of BCL6 overexpression and knockdown were, respectively, investigated in Ang II-treated human VSMCs. Therapeutical effects of BCL6 overexpression on vascular remodeling, oxidative stress, and proliferation were determined in the aorta of spontaneously hypertensive rats (SHR). Ang II reduced BCL6 expression in human VSMCs. BCL6 overexpression attenuated while BCL6 knockdown enhanced the Ang II-induced upregulation of NADPH oxidase 4 (NOX4), production of reactive oxygen species (ROS), and proliferation of VSMCs. BCL6 expression was downregulated in SHR. BCL6 overexpression in SHR reduced NOX4 expression, ROS production, and proliferation of the aortic media of SHR. Moreover, BCL6 overexpression attenuated vascular remodeling and hypertension in SHR. However, BCL6 overexpression had no significant effects on NOX2 expression in human VSMCs or in SHR. We conclude that BCL6 attenuates proliferation and oxidative stress of VSMCs in hypertension.

Aortic Graft at Coronary Artery Bypass Surgery as a Source of Human Aortic Smooth Muscle Cells

One of the serious obstacles of the aortopathies research is a considerable shortage of human aortic smooth muscle cells (SMCs), which can be used to model the disease. SMC in most cases come from the whole aorta of transplant donors, which are rather difficult to access. In the course of coronary artery bypass graft (CABG) surgery, a fragment of aortic tissue is excised to make a bypass root. In this study, we show a possibility to use CABG leftover fragments of thoracic aorta as a source of human SMC for in vitro research. We isolated SMC from the fragments of aortic tissues obtained during CABG procedure and compared these cells to the cells that were isolated from aortic tissue of transplant donors. The content of key SMC contractile markers (SMA, SM22α, and vimentin) as well as proliferation and migration rates, metalloproteases MMP-2 and MMP-9 activities were similar in CABG-derived SMC and in transplant donor–derived SMC. In conclusion, leftovers of ascending thoracic aorta obtained during CABG can be used as a source of human aortic SMCs for in vitro research.

Phenotypic and Functional Changes of Endothelial and Smooth Muscle Cells in Thoracic Aortic Aneurysms

Thoracic aortic aneurysm develops as a result of complex series of events that alter the cellular structure and the composition of the extracellular matrix of the aortic wall. The purpose of the present work was to study the cellular functions of endothelial and smooth muscle cells from the patients with aneurysms of the thoracic aorta. We studied endothelial and smooth muscle cells from aneurysms in patients with bicuspid aortic valve and with tricuspid aortic valve. The expression of key markers of endothelial (CD31, vWF, and VE-cadherin) and smooth muscle (SMA, SM22α, calponin, and vimentin) cells as well extracellular matrix and MMP activity was studied as well as and apoptosis and cell proliferation. Expression of functional markers of endothelial and smooth muscle cells was reduced in patient cells. Cellular proliferation, migration, and synthesis of extracellular matrix proteins are attenuated in the cells of the patients. We show for the first time that aortic endothelial cell phenotype is changed in the thoracic aortic aneurysms compared to normal aortic wall. In conclusion both endothelial and smooth muscle cells from aneurysms of the ascending aorta have downregulated specific cellular markers and altered functional properties, such as growth rate, apoptosis induction, and extracellular matrix synthesis.