On the basis of material comprising 10 developmental stages of man in 35 embryonic series, the authors tried to determine the critical developmental period of the blood vessel wall. This period falls between the 5th and 16th weeks of intrauterine life, that is in the period of the formation of the basic wall structure characteristic of the particular vessel type (i. e. the elastic and muscular arteries, large veins, limb veins, and lymphatics). In limbs the differences between the superficial and deep veins as regards the vessel wall development, were disclosed.
- MeSH
- Leg blood supply MeSH
- Blood Vessels embryology MeSH
- Humans MeSH
- Lymphatic System embryology MeSH
- Arm blood supply MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
The development of an ideal vascular prosthesis represents an important challenge in terms of the treatment of cardiovascular diseases with respect to which new materials are being considered that have produced promising results following testing in animal models. This study focuses on nanofibrous polycaprolactone-based grafts assessed by means of histological techniques 10 days and 6 months following suturing as a replacement for the rat aorta. A novel stereological approach for the assessment of cellular distribution within the graft thickness was developed. The cellularization of the thickness of the graft was found to be homogeneous after 10 days and to have changed after 6 months, at which time the majority of cells was discovered in the inner layer where the regeneration of the vessel wall was found to have occurred. Six months following implantation, the endothelialization of the graft lumen was complete, and no vasa vasorum were found to be present. Newly formed tissue resembling native elastic arteries with concentric layers composed of smooth muscle cells, collagen, and elastin was found in the implanted polycaprolactone-based grafts. Moreover, the inner layer of the graft was seen to have developed structural similarities to the regular aortic wall. The grafts appeared to be well tolerated, and no severe adverse reaction was recorded with the exception of one case of cartilaginous metaplasia close to the junctional suture.
- Keywords
- electrospinning, histological evaluation, polycaprolactone, stereology, vascular graft, vascular remodeling,
- Publication type
- Journal Article MeSH
Cardiovascular disease is anticipated to remain the leading cause of death globally. Due to the current problems connected with using autologous arteries for bypass surgery, researchers are developing tissue-engineered vascular grafts (TEVGs). The major goal of vascular tissue engineering is to construct prostheses that closely resemble native blood vessels in terms of morphological, mechanical, and biological features so that these scaffolds can satisfy the functional requirements of the native tissue. In this setting, morphology and cellular investigation are usually prioritized, while mechanical qualities are generally addressed superficially. However, producing grafts with good mechanical properties similar to native vessels is crucial for enhancing the clinical performance of vascular grafts, exposing physiological forces, and preventing graft failure caused by intimal hyperplasia, thrombosis, aneurysm, blood leakage, and occlusion. The scaffold's design and composition play a significant role in determining its mechanical characteristics, including suturability, compliance, tensile strength, burst pressure, and blood permeability. Electrospun prostheses offer various models that can be customized to resemble the extracellular matrix. This review aims to provide a comprehensive and comparative review of recent studies on the mechanical properties of fibrous vascular grafts, emphasizing the influence of structural parameters on mechanical behavior. Additionally, this review provides an overview of permeability and cell growth in electrospun membranes for vascular grafts. This work intends to shed light on the design parameters required to maintain the mechanical stability of vascular grafts placed in the body to produce a temporary backbone and to be biodegraded when necessary, allowing an autologous vessel to take its place.
- Keywords
- biopolymers, burst pressure, cellular activity, compliance, fiber orientation, permeability, physiological forces, porosity, vascular grafts, wall thickness,
- Publication type
- Journal Article MeSH
- Review MeSH
AIM: The aim of this study was to evaluate short-term patency of the new prosthetic graft and its structural changes after explantation. METHODS: The study team developed a three-layer conduit composed of a scaffold made from polyester coated with collagen from the inner and outer side with an internal diameter of 6 mm. The conduit was implanted as a bilateral bypass to the carotid artery in 7 sheep and stenosis was created in selected animals. After a period of 161 days, the explants were evaluated as gross and microscopic specimens. RESULTS: The initial flow rate (median ± IQR) in grafts with and without artificial stenosis was 120 ± 79 ml/min and 255 ± 255 ml/min, respectively. Graft occlusion occurred after 99 days in one of 13 conduits (patency rate: 92%). Wall-adherent thrombi occurred only in sharp curvatures in two grafts. Microscopic evaluation showed good engraftment and preserved structure in seven conduits; inflammatory changes with foci of bleeding, necrosis, and disintegration in four conduits; and narrowing of the graft due to thickening of the wall with multifocal separation of the outer layer in two conduits. CONCLUSIONS: This study demonstrates good short-term patency rates of a newly designed three-layer vascular graft even in low-flow conditions in a sheep model.
- MeSH
- Carotid Arteries drug effects MeSH
- Blood Vessel Prosthesis MeSH
- Blood Vessel Prosthesis Implantation methods MeSH
- Collagen metabolism MeSH
- Graft Occlusion, Vascular drug therapy MeSH
- Sheep MeSH
- Prospective Studies MeSH
- Prosthesis Design methods MeSH
- Vascular Patency drug effects MeSH
- Plastic Surgery Procedures methods MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Collagen MeSH
One of the causes of fixation of elevated blood pressure are structural changes in the arterial wall manifested at first by hypertrophy of the smooth muscle and later by proliferation of connective tissue. These changes can be evaluated in humans from the degree of vasodilatation during reactive hyperaemia. We found that the inability of adequate vasodilatation is typical for all types of hypertension, i.e. essential hypertension in young and elderly subjects stage I and II, and vasorenal hypertension. On the other hand, in patients with borderline hypertension structural changes do not develop. The inability of adequate vasodilatation in patients with hypertension persists also during a short-term reduction of the blood pressure to normal values as a result of therapy. In patients operated successfully on account of vasorenal hypertension the normal vasodilatation capacity is regained after one year of normalization of blood pressure.
- MeSH
- Leg blood supply MeSH
- Vascular Resistance * MeSH
- Blood Vessels pathology MeSH
- Adult MeSH
- Hypertension pathology physiopathology MeSH
- Hypertrophy MeSH
- Blood Pressure MeSH
- Middle Aged MeSH
- Humans MeSH
- Hypertension, Renovascular physiopathology MeSH
- Vasodilation MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Publication type
- Journal Article MeSH
Vascular repair in response to injury or stress (often referred to as remodeling) is a common complication of many cardiovascular abnormalities including pulmonary hypertension, systemic hypertension, atherosclerosis, vein graft remodeling and restenosis following balloon dilatation of the coronary artery. It is not surprising that repair and remodeling occurs frequently in the vasculature in that exposure of blood, vessels to either excessive hemodynamic stress (e.g. hypertension), noxious blood borne agents (e.g. atherogenic lipids), locally released cytokines, or unusual environmental conditions (e.g. hypoxia), requires readily available mechanisms to counteract these adverse stimuli and to preserve structure and function of the vessel wall. The responses, which were presumably evolutionarily developed to repair an injured tissue, often escape self-limiting control and can result, in the case of blood vessels, in lumen narrowing and obstruction to blood flow. Each cell type (i. e. endothelial cells, smooth muscle cells, and fibroblasts) in the vascular wall plays a specific role in the response to injury. However, while the roles of the endothelial cells and smooth muscle cells (SMC) in vascular remodeling have been extensively studied, relatively little attention has been given to the adventitial fibroblasts. Perhaps this is because the fibroblast is a relatively ill-defined cell which, at least compared to the SMC, exhibits few specific cellular markers. Importantly though, it has been well demonstrated that fibroblasts possess the capacity to express several functions such as migration, rapid proliferation, synthesis of connective tissue components, contraction and cytokine production in response to activation or stimulation. The myriad of responses exhibited by the fibroblasts, especially in response to stimulation, suggest that these cells could play a pivotal role in the repair of injury. This fact has been well documented in the setting of wound healing where a hypoxic environment has been demonstrated to be critical in the cellular responses. As such it is not surprising that fibroblasts may play an important role in the vascular response to hypoxia and/or injury. This paper is intended to provide a brief review of the changes that occur in the adventitial fibroblasts in response to vascular stress (especially hypoxia) and the role the activated fibroblasts might play in hypoxia-mediated pulmonary vascular disease.
- MeSH
- Cell Death MeSH
- Cell Division MeSH
- Blood Vessels physiopathology MeSH
- Fibroblasts pathology physiology MeSH
- Hypoxia physiopathology MeSH
- Humans MeSH
- Pulmonary Circulation * MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Primary aldosteronism (PA) is a common form of arterial hypertension with a high prevalence of cardiovascular complications. In patients with PA, complex mechanisms may lead to functional and/or structural abnormalities of the blood vessel wall. Clinical evidence indicates that patients with PA may have immune cell activation, increased oxidative stress, impaired endothelial function and vascular remodeling. Activation of fibroproliferation has been found in resistant arteries of patients with PA. Subjects with PA compared to essential hypertensives with similar blood pressure levels have increased intima-media thickness and arterial stiffness as measured by pulse wave velocity. These functional and morphological changes can be modified by an increased sodium intake. Vascular remodeling in PA may indicate a poor response to specific therapy with lower probability of cure and/or normalization of blood pressure. Early diagnosis of PA before blood vessel wall disturbances develop is of utmost importance.
- MeSH
- Vascular Resistance physiology MeSH
- Hyperaldosteronism diagnosis epidemiology physiopathology MeSH
- Hypertension diagnosis epidemiology physiopathology MeSH
- Blood Pressure physiology MeSH
- Humans MeSH
- Vascular Diseases diagnosis epidemiology physiopathology MeSH
- Blood Flow Velocity physiology MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
The endothelium lines all blood vessels in the human body, it is the basic structure which ensures the action of substances circulating in the blood stream on the vascular wall. It is an organ the sound state of which is essential for the physiological function of the vascular system. Its impaired function is a basic factor in the genesis and development of vascular disease. Under physiological conditions the endothelium has antiadhesive and antithrombotic properties, it produces vasoactive substances, prevents the penetration of circulating substances and formed elements across the vascular wall, and via adhesion molecules it participates in the interaction with cells in the circulation. Risk factors of cardiovascular diseases such as hypertension, hyperlipidaemia, hyperglycaemia, smoking damage the function of endothelial cells and cause the development of endothelial dysfunction. In patients with arterial hypertension endothelial dysfunction is characterized by an impaired endothelium dependent relaxation, increased adhesion and permeability of endothelial cells, structural changes of the vascular wall. When the endothelium is damaged by released cytokines an increased expression of adhesion molecules occurs, adhesion and migration of inflammatory cells across the vascular wall. Cytoadhesion molecules are released from the surface of the endothelium into the circulation where the rise of their plasma levels can serve as a marker of endothelial damage. Endothelial dysfunction in hypertonic subjects contributes in a significant way to the development and progression of chronic vascular disease--atherosclerosis. Improvement of the damaged endothelial function is therefore at present a desirable therapeutic objective in the treatment of hypertension.
- MeSH
- Arteriosclerosis physiopathology MeSH
- Endothelium, Vascular physiopathology MeSH
- Hypertension physiopathology MeSH
- Humans MeSH
- Check Tag
- Humans MeSH
- Publication type
- English Abstract MeSH
- Journal Article MeSH
- Review MeSH
Vascular system is a large complex of tubes with different diameters which are able to perceive changes of endogenous milieu, to integrate and modulate signals of intercellular communication and to respond and adapt by a local production of different kinds of mediators affecting vascular structure and function. For a long time, it has been assumed that the main determinant of vasomotor function was the nervous system and the monolayer of endothelial cells was only a physical barrier between the vessel wall and blood. However, the first publications in 1960s and 70s indicated that endothelium is not only a passive barrier. Endothelium features autocrine, paracrine and endocrine activities. Vascular endothelium plays an important role in the regulation of vascular tone, blood pressure and blood flow beside central regulation of nervous system. The existence of endothelium-derived relaxing factor (EDRF) was found out by Furchgott and Zawadzki (1980) who showed that acetylcholine induced relaxation of the rabbit aorta only in the presence of intact endothelium. Nowadays, nitric oxide (NO), previously known as EDRF, is considered one of the crucial endothelium-derived vasorelaxing substances participating in the regulation of basal vascular tone, vascular resistance and thus in the regulation of blood pressure. Arterial bed is dilated continuously as a consequence of constant production of NO. Any damage of endothelium modifies regulatory functions of endothelial cells. These conditions are characterised as endothelial dysfunction associated with imbalance between vasodilating and vasoconstricting factors, pro- and anticoagulation factors and factors stimulating and inhibiting growth and proliferation of cells. However, cellular mechanisms which are involved in the development of endothelial dysfunction, are still not well-known.
- MeSH
- Endothelium, Vascular physiology physiopathology MeSH
- Blood Pressure physiology MeSH
- Humans MeSH
- Nitric Oxide physiology MeSH
- Vasodilation physiology MeSH
- Vasoconstriction physiology MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- English Abstract MeSH
- Journal Article MeSH
- Review MeSH
- Names of Substances
- Nitric Oxide MeSH
The opening angles of 16 rings excised from human coronary arteries with different degrees of atherosclerosis were determined 10 hours after death. Atherosclerosis, as a chronic inflammatory response of arterial endothelium and intima, is defined by three degrees of its development. The opening angle decreases more or less linearly with the distance from the right coronary artery orifice. This is in accordance with the functional requirements posed on blood transport into the coronary arteries. A decrease of the opening angle with age is affected by hardening of the arterial wall, among other factors. This is in accordance with a stochastic model of age related changes in the initial modulus of elasticity of the coronary artery. A part of the free energy of smooth muscle cells, fibroblasts, collagen and elastic fibres is used not for creating residual strain but for remodeling the arterial wall structure. The opening angle is also considerably affected by the degree of atheroclerosis. The dependence on age of the external diameter and the thickness of the intact left and right coronary arteries in the vicinity of the aortic sinus was also analyzed in two female and two male subjects. To ensure the objectivity of the results it is necessary to carry out additional experiments and studies in vivo.
- MeSH
- Models, Biological MeSH
- Endothelium, Vascular pathology physiopathology MeSH
- Child MeSH
- Adult MeSH
- Elastic Tissue pathology physiopathology MeSH
- Fibroblasts pathology physiology MeSH
- Infant MeSH
- Collagen physiology ultrastructure MeSH
- Coronary Vessels pathology physiopathology MeSH
- Coronary Circulation physiology MeSH
- Middle Aged MeSH
- Humans MeSH
- Stress, Mechanical MeSH
- Adolescent MeSH
- Coronary Artery Disease pathology physiopathology MeSH
- Infant, Newborn MeSH
- Child, Preschool MeSH
- Elasticity MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Aging pathology physiology MeSH
- Stochastic Processes MeSH
- Muscle, Smooth, Vascular pathology physiopathology MeSH
- Tunica Intima pathology physiopathology MeSH
- Check Tag
- Child MeSH
- Adult MeSH
- Infant MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Male MeSH
- Infant, Newborn MeSH
- Child, Preschool MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Collagen MeSH
