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Mechanotransduction of Cardiovascular Development and Regeneration
Published in Juhyun Lee, Sharon Gerecht, Hanjoong Jo, Tzung Hsiai, Modern Mechanobiology, 2021
Quinton Smith, Justin Lowenthal, Sharon Gerecht
In general, there are over 20 known members of the integrin family constructed by 8b and 18a subunits. Some of the integrins resident to cardiomyocytes include binding motifs for collagen type I (α3β1), laminin (α1β1, a3b1, and α7β1), and fibronectin (α3β1 and α5β1) [37]. While ECs are anchored to the vessel wall by nearly 20 different ECM proteins, the 2D mesh primarily contains collagen IV, laminin, fibronectin, and proteoglycan perlecan [38]. A thin membrane called the tunica intima, composed of collagen VI and VIII, separates ECs from the tunica media. The tunica media, which is typically thickened in arteries, contains supportive mural cell populations, namely smooth muscle cells, which are found in large arteries and veins, and pericytes, which reside in small capillaries. The specific ECM contribution to vasculature is dependent on tissue function. Vascular tone is mediated, in part, by the elastic nature of the ECM proteins fibrillin and elastin. Where vessel elasticity is not essential, as in the case of vascularized muscle tissues, whose role is to distribute blood to different organs, the ECM is enriched with concentric layers of smooth muscle cell sheaths.
Cardiovascular System:
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The tunica media is the middle layer of the vessel wall. It is made up of both smooth muscle and connective tissue and shows the greatest variation among the blood vessels of the circulatory system. When the smooth muscle contracts in vasoconstriction, there is a decrease in radius, an increase in resistance, and a resulting decrease in blood flow. The external elastic lamina forms the outer portion of the tunica media. The tunica externa (or adventitia) is made up of collagen and elastin fibers, which contribute to the mechanical properties of the blood vessels. It also helps anchor the vessels to the surrounding tissue. In the larger vessels, there are small blood vessels (the vasa vasorum) that supply the outer layers of the blood vessel wall with oxygen and nutrients. A weakened area of the wall with less connective tissue reinforcement may result in a region of expansion (a “bulge”) known as an aneurysm. This could be a result of a genetic defect (such as Marfan’s syndrome) or a disease state such as atherosclerosis and syphilis. If the wall becomes further stretched, it may result in rupture. Surgery is often done to repair this and prevent further rupture. This will be discussed further in Chapter 6.
Potential Targets for Imaging Atherosclerosis
Published in Robert J. Gropler, David K. Glover, Albert J. Sinusas, Heinrich Taegtmeyer, Cardiovascular Molecular Imaging, 2007
David N. Smith, Mehran M. Sadeghi, Jeffrey R. Bender
The normal blood vessel is comprised of three distinct layers or tunicae divided by internal and external elastic laminae. While mainly composed of both collagen and elastin connective tissue, each layer has particular cell types responsible for specific function. The innermost layer, the tunica intima, is separated from the vessel lumen by a thin layer of endothelial cells (EC), containing fibroblasts and myointimal cells in its sub-endothelial support structure. It is responsible for many regulatory mechanisms, including control of cell adhesion and transmigration as well as diffusion of fluid and macromolecules. The medial layer, or tunica media, contains vascular smooth muscle cells (VSMC), thus, contractile elements that under normal physiologic states and in response to intimal signals, determines vessel lumen diameter. The outer tunica adventitia is a supporting layer of the vessel that harbors the vascular supply (vasovasorum) as well as connective tissue and fibroblasts. Resident leukocytes, specifically T cells and monocyte derivatives [macrophages and dendritic cells (DC)] are normally present in insignificant levels within the vessel wall. This is partially due to EC-derived nitric oxide (NO), which serves as a potent inhibitor of platelet aggregation and leukocyte adhesion. Other cell types, including mesenchymal-derived pericytes, are present largely around the blood vessels in the adventitial layers.
Ginkgo biloba modulates ET-I/NO signalling in Lead Acetate induced rat model of endothelial dysfunction: Involvement of oxido-inflammatory mediators
Published in International Journal of Environmental Health Research, 2023
Jerome Ndudi Asiwe, Godwin D. Yovwin, Nwoke Enekabokom Ekene, Simon Irikefe Ovuakporaye, Anthony Chibuzor Nnamudi, Eze Kingsley Nwangwa
The structures of blood vessels are well adapted to suit their functions. These blood vessels stratify to form structures such as tunica adventitia which provides the structural support and shape of the vessel, tunica media which is composed of elastic and muscular tissues that regulate the internal diameter of the vessels and the tunica intima consisting of an endothelial lining which provides a frictionless pathway for the movement of blood. However, within each layer, the amount of muscle and collagen fibrils varies depending on the size and location of the vessels (de Lucio et al. 2021). In this study, lead exposure significantly disturbed the usual histoarchitecture of the aorta as revealed by changes in the tunica intima. This was consistent with previous reports in rats with lead-induced oxidative damage and hyperlipidemia (Sanusi et al. 2020; Asiwe et al. 2022). On the other hand, the morphology of the aorta in Ginkgo biloba-treated rats appeared to be normal. This showed that Ginkgo biloba extract has the ability to protect against lead-induced structural changes.
Medical textiles
Published in Textile Progress, 2020
There are three types of vessels: arteries, veins and capillaries. Arteries and veins are composed of three distinct layers; tunica intima, tunica media and tunica adventitia. In arteries, the intima is composed of a single layer of epithelial cells (endothelium) supported by a basement membrane and elastic lamina. The media contains circular smooth muscle cells and an elastin-rich cellular matrix whereas the adventitia is composed of loose connective tissue, fibroblasts, nerve endings and vasa vasorum (blood supply to the vessel) [335]. Arteries can be divided into large elastic arteries, medium muscular arteries and small arteries. Veins are capacitance vessels that operate under low-pressure conditions and are larger and thinner-walled than arteries. There are fewer smooth muscle cells in the tunica media. The basic structural components allow for the vasculature to regulate blood flow by changing luminal area and wall thickness. As the vessels are living tissues, damage to them or the introduction of foreign material results in endothelial dysfunction leading to an inflammatory response resulting in atherosclerosis.
Physico-mechanical and biological evaluation of heparin/VEGF-loaded electrospun polycaprolactone/decellularized rat aorta extracellular matrix for small-diameter vascular grafts
Published in Journal of Biomaterials Science, Polymer Edition, 2022
John Patrick Cuenca, Hoe-Jin Kang, Md. Abdullah Al Fahad, Myeongki Park, Minji Choi, Hyun-Yong Lee, Byong-Taek Lee
Native aorta contains a thick middle layer, also known as tunica media, which is made of smooth-muscle cells. So, in our study we checked whether there is any trace of smooth-muscle cell regeneration by staining α-SMA marker [26]. After 2 weeks (Figure 11a), the PCL group showed a very small presence of the marker, which was elevated slightly after 4 weeks (Figure 11d). The PCL/ECM group showed a prolific amount of α-SMA after 2 weeks (Figure 11b) and 4 weeks (Figure 11e). After 2 weeks, the PCL/ECM/VEGF (Figure 11c) group showed better results even when compared to the 4-week group of PCL/ECM. After 4 weeks, we could observe the pervasive distribution of α-SMA marker all over the grafts of the PCL/ECM/VEGF (Figure 11f) group.