scholarly journals EXPERIMENTAL ARTERIOSCLEROSIS

1972 ◽  
Vol 136 (4) ◽  
pp. 769-789 ◽  
Author(s):  
Michael B. Stemerman ◽  
Russell Ross
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Balloon Catheter ◽  
Muscle Cells ◽  
Endothelial Injury ◽  
Macaca Nemestrina ◽  
Elastic Fibers ◽  
Internal Elastic Lamina ◽  
Principal Factors ◽  
Elastic Lamina

Arteriosclerotic lesions have been produced in monkeys (Macaca nemestrina) by selective removal of the vascular endothelium with an intra-arterial balloon catheter. Immediately after de-endothelialization a platelet layer covers the denuded area. This thrombus is gradually removed and by 7 days the vessel appears to be largely reendothelialized. Beginning at day 4, smooth muscle cells undergo modification and migrate through fenestrae in the internal elastic lamina into the intima where they proliferate. By 28 days, the intimal lesion consists of multiple layers of smooth muscle cells surrounded by collagen and elastic fibers and basement-like material. After 3 months the lesions are markedly hyperplastic and contain new extracellular connective tissue elements. In contrast, with no further injury after 6 months the lesion has decreased markedly in size suggesting that it may be reversible in the absence of continued endothelial injury. The importance of endothelial "injury" exposing medial smooth muscle to plasma constituents may be the principal factors associated with the migration and proliferation of the smooth muscle cells into the intima resulting in the lesion. The smooth muscle cells do not contain lipid. The similarities of this lesion to the fibromusculo-elastic lesion or preatherosclerotic intimal hyperplasia in man makes it a useful model for the further study of atherosclerosis.

scholarly journals Proteoglycans in primate arteries. I. Ultrastructural localization and distribution in the intima.

1975 ◽  
Vol 67 (3) ◽  
pp. 660-674 ◽  
Author(s):  
T N Wight ◽  
R Ross
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Ultrastructural Localization ◽  
Ruthenium Red ◽  
Basement Membranes ◽  
Macaca Nemestrina ◽  
Elastic Fibers ◽  
Surface Coat ◽  
The Matrix

Proteoglycans were identified and localized histochemically and ultrastructurally in normal and hyperplastic arterial intimas in nonhuman primates (Macaca nemestrina). These regions were consistently more alcianophilic than the adjacent medial layers and this alcianophilia was absent after treatment with glycosaminoglycan-degradative enzymes. Ultrastructurally, the intimal intercellular matrix consisted of numerous, irregularly shaped, 200-500-A diameter granules possessing 30--60-A diameter filamentous projections, and these granules were dispersed between collagen and elastic fibers. The granules exhibited a marked affinity for ruthenium red and were interconnected via their filamentous projections. The ruthenium red-positive granules were intimately associated with the plasma membrane of intimal smooth muscle cells and attached to collagen fibrils and elastic fibers. The matrix granules were completely removed after testicular hyaluronidase or chondroitinase ABC digestion but only partially removed after leech hyaluronidase treatment. These results suggest that the matrix granules contain some hyaluronic acid and one or more isomers of chondroitin sulfate. In addition to the large ruthenium red-positive matrix granules, a smaller class of ruthenium red-positive granule (100--200-A diameter) was present within the basement membranes beneath the endothelium and surrounding the smooth muscle cells. Ruthenium red also exhibited an affinity for the surface coat of the smooth muscle cells. The potential importance of proteoglycans in arterial intimal hyperplasia is discussed.

Interstitial flow through the internal elastic lamina affects shear stress on arterial smooth muscle cells

2000 ◽  
Vol 278 (5) ◽  
pp. H1589-H1597 ◽  
Author(s):  
Shigeru Tada ◽  
John M. Tarbell
Keyword(s):  
Shear Stress ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Shear Stresses ◽  
Interstitial Flow ◽  
Internal Elastic Lamina ◽  
Tunica Media ◽  
Flow Through ◽  
Elastic Lamina

Interstitial flow through the tunica media of an artery wall in the presence of the internal elastic lamina (IEL), which separates it from the subendothelial intima, has been studied numerically. A two-dimensional analysis applying the Brinkman model as the governing equation for the porous media flow field was performed. In the numerical simulation, the IEL was modeled as an impermeable barrier to water flux, except for the fenestral pores, which were uniformly distributed over the IEL. The tunica media was modeled as a heterogeneous medium composed of a periodic array of cylindrical smooth muscle cells (SMCs) embedded in a fiber matrix simulating the interstitial proteoglycan and collagen fibers. A series of calculations was conducted by varying the physical parameters describing the problem: the area fraction of the fenestral pore (0.001–0.036), the diameter of the fenestral pore (0.4–4.0 μm), and the distance between the IEL and the nearest SMC (0.2–0.8 μm). The results indicate that the value of the average shear stress around the circumference of the SMC in the immediate vicinity of the fenestral pore could be as much as 100 times greater than that around an SMC in the fully developed interstitial flow region away from the IEL. These high shear stresses can affect SMC physiological function.

Flow through internal elastic lamina affects shear stress on smooth muscle cells (3D simulations)

2002 ◽  
Vol 282 (2) ◽  
pp. H576-H584 ◽  
Author(s):  
Shigeru Tada ◽  
John M. Tarbell
Keyword(s):  
Shear Stress ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Pore Diameter ◽  
Muscle Cells ◽  
Bottom Surface ◽  
Interstitial Flow ◽  
Internal Elastic Lamina ◽  
Flow Through ◽  
Elastic Lamina

We describe a three-dimensional numerical simulation of interstitial flow through the medial layer of an artery accounting for the complex entrance condition associated with fenestral pores in the internal elastic lamina (IEL) to investigate the fluid mechanical environment around the smooth muscle cells (SMCs) right beneath the IEL. The IEL was modeled as an impermeable barrier to water flow except for the fenestral pores, which were assumed to be uniformly distributed over the IEL. The medial layer was modeled as a heterogeneous medium composed of a periodic array of cylindrical SMCs embedded in a continuous porous medium representing the interstitial proteoglycan and collagen matrix. Depending on the distance between the IEL bottom surface and the upstream end of the proximal layer of SMCs, the local shear stress on SMCs right beneath the fenestral pore could be more than 10 times higher than that on the cells far removed from the IEL under the conditions that the fenestral pore diameter and area fraction of pores were kept constant at 1.4 μm and 0.05, respectively. Thus these proximal SMCs may experience shear stress levels that are even higher than endothelial cells exposed to normal blood flow (order of 10 dyn/cm2). Furthermore, entrance flow through fenestral pores alters considerably the interstitial flow field in the medial layer over a spatial length scale of the order of the fenestral pore diameter. Thus the spatial gradient of shear stress on the most superficial SMC is noticeably higher than computed for endothelial cell surfaces.

Phenotypic Modulation of Smooth Muscle Cells after Arterial Injury Is Associated with Changes in the Distribution of Laminin and Fibronectin

1997 ◽  
Vol 45 (6) ◽  
pp. 837-846 ◽  
Author(s):  
Johan Thyberg ◽  
Karin Blomgren ◽  
Joy Roy ◽  
Phan Kiet Tran ◽  
Ulf Hedin
Keyword(s):  
Smooth Muscle ◽  
Basement Membrane ◽  
Smooth Muscle Cells ◽  
Actin Filaments ◽  
Cell Structure ◽  
Muscle Cells ◽  
Arterial Injury ◽  
Internal Elastic Lamina ◽  
Contractile Phenotype

Earlier in vitro studies suggest opposing roles of laminin and fibronectin in regulation of differentiated properties of vascular smooth muscle cells. To find out if this may also be the case in vivo, we used immunoelectron microscopy to study the distribution of these proteins during formation of intimal thickening after arterial injury. In parallel, cell structure and content of smooth muscle α-actin was analyzed. The results indicate that the cells in the normal media are in a contractile phenotype with abundant α-actin filaments and an incomplete basement membrane. Within 1 week after endothelial denudation, most cells in the innermost layer of the media convert into a synthetic phenotype, as judged by loss of actin filaments, construction of a large secretory apparatus, and destruction of the basement membrane. Some of these cells migrate through fenestrae in the internal elastic lamina and invade a fibronectin-rich network deposited on its luminal surface. Within another few weeks a thick neointima forms, newly produced matrix components replace the strands of fibronectin, and a basement membrane reappears. Simultaneously, the cells resume a contractile phenotype, recognized by disappearance of secretory organelles and restoration of α-actin filaments. These findings support the notion that laminin and other basement membrane components promote the expression of a differentiated smooth muscle phenotype, whereas fibronectin stimulates the cells to adopt a proliferative and secretory phenotype.

The Role of Endothelial Cell Injury and Platelet Response in Atherogenesis

1977 ◽  
Author(s):  
L. A. Harker ◽  
R. Ross ◽  
J. Glomset
Keyword(s):  
Smooth Muscle ◽  
Endothelial Cell ◽  
Connective Tissue ◽  
Smooth Muscle Cells ◽  
Lipid Accumulation ◽  
Blood Platelets ◽  
Muscle Cells ◽  
Endothelial Injury ◽  
Intimal Proliferation ◽  
Flowing Blood

Endothelium forms a resistant barrier between flowing blood and vessel wall structures. Endothelial thromboresistance is maintained in part by the synthesis of prostacyclin, a potent prostaglandin inhibitor of platelet function. Loss of endothelial cells, mediated by physical, chemical, infectious or immune mechanisms, exposes the sub endothelium to flowing blood. Platelets react to the subendothelial connective tissue structures, undergoing adhesion and release of intracellular constituents, including a factor that is mitogenic to smooth muscle cells. This growth factor is a heat stable, basic protein (IP 7.4–9.4) of 20,000 Daltons and appears to be responsible for the intimal proliferation of smooth muscle cells that follows endothelial cell desquamation. After a single injury event the intimal lesion regresses over several months. Repeated or continuous endothelial cell loss results in progressive intimal proliferation of smooth muscle cells, their secretion of connective tissue matrix components (collagen, elastin and proteoglycans) and accumulation of lipid when animals are on a hypercholesterolemic diet to form early atherosclerotic intimal lesions. Discontinuance of endothelial injury and restoration of the endothelium appear to be followed by lesion regression except when lipid accumulation is extensive. Possible approaches to atherosclerosis prevention include: 1) protection of the endothelium by interruption or avoidance of endothelial injury factors, and perhaps by pharmacologic protection; 2) inhibition of platelet reactivity; 3) modification of SMC proliferation, secretion or lipid accumulation.

Platelet And Smooth Muscle Cell Responses After Endothelial Desquamation

1981 ◽  
Author(s):  
M B Stemerman
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Abdominal Aorta ◽  
Vessel Wall ◽  
Balloon Catheter ◽  
Muscle Cells ◽  
Mechanical Removal ◽  
Cell Counts ◽  
Old Rats

Although compromise of endothelial integrity occurs through many mechanisms, mechanical removal by balloon catheter is an excellent experimental method to study vascular responsiveness after injury. The interaction of platelets with the vessel wall, as well as proliferation of vascular smooth muscle cells can be assessed in this model. Following platelet attachment to the subendothelium, platelets release materials from their alpha granules. Using an antibody raised against platelet factor 4, a protein stored in alpha granules, we have demonstrated that material released from platelets do enter the vessel wall. A large amount of PF 4 antigen enters the wall shortly after endothelial removal, permeating the wall completely by 30 minutes, but little trace of the antigen can be found four hours after injury. Using infusions of PGI2 to a level of 850 ng/kg/min in rabbits, in vivo platelet adhesion to the exposed subendothelium can be greatly reduced and release of PF4 antigen into the vessel wall markedly diminished. Growth of smooth muscle cells (SMC) after endothelial removal has also been measured by 3H-Thymidine labeling of SMC DNA. As measured by this method as well as direct cell counts, SMC proliferation in the abdominal aorta is significantly greater than the thoracic. Reinjury of only the abdominal aorta by balloon catheter 4 days after the initial total aortic injury causes a proliferative spurt in the thoracic aortic SMC, thus demonstrating that a humoral signal can initiate SMC proliferation. In addition, the response of SMC from 21 month old rats when compared with 3 month old rats is much greater. These studies demonstrate in vivo methods for examining the response of platelets and SMC following endothelial injury. Further, these studies indicate that the response to injury hypothesis of atherosclerosis progression should now be broadened to the concept of a response to signal view of atherogenesis.

An Arteriovenous Malformation Model for Stereotactic Radiosurgery Research

Neurosurgery ◽  
2007 ◽  
Vol 61 (1) ◽  
pp. 152-159 ◽  
Author(s):  
Reza Jahan ◽  
Timothy D. Solberg ◽  
Daniel Lee ◽  
Paul Medin ◽  
Satoshi Tateshima ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Arteriovenous Malformation ◽  
Smooth Muscle Cells ◽  
Stereotactic Radiosurgery ◽  
Intimal Hyperplasia ◽  
Morphological Changes ◽  
Muscle Cells ◽  
Collagen Type Iv ◽  
Internal Elastic Lamina ◽  
Type Iv

Abstract OBJECTIVE To introduce the utilization of a swine arteriovenous malformation (AVM) model for stereotactic radiosurgery research and to describe the morphological changes in the vessels after radiation. METHODS The model was created in six animals by creation of a right-sided carotid-jugular fistula. Pre- and postsurgical hemodynamic evaluation was performed. The left rete was radiated in four animals; two animals were not radiated. All animals were sacrificed 4 months after surgery, and the bilateral retia were obtained at autopsy. RESULTS There were no procedure-related complications. A pressure gradient of 20 mmHg across the nidus was obtained after surgery. The peak velocity in the arterial feeder increased from 18.5 to 83 cm/s. Microscopic examination of the control animals showed intimal hyperplasia and disrupted internal elastic lamina, similar to human AVMs. The radiated retia showed more prominent intimal hyperplasia. This was confirmed by histometric studies showing greater luminal occlusion in radiated specimens. Adventitial fibrosis was prominent in the radiated retia and was absent in the control animals. Immunohistochemical studies showed proliferating smooth muscle cells in the intima. The adventitial fibrosis consisted of smooth muscle cells surrounded by collagen Type IV extracellular matrix. CONCLUSION The nidus component and high-flow vasculopathy make this an attractive model for stereotactic radiosurgery research. Histology of the radiated models is similar to those described in radiated human AVMs. Further studies of the model are warranted to gain a better understanding of the cellular and molecular events in AVM vessels after stereotactic radiosurgery.

Different radiosensitivity of smooth muscle cells and endothelial cells in vitro as demonstrated by irradiation from a Re-188 filled balloon catheter

2000 ◽  
Vol 152 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Jörg Kotzerke ◽  
Ralf Gertler ◽  
Inga Buchmann ◽  
Regine Baur ◽  
Vinzenz Hombach ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Balloon Catheter ◽  
Muscle Cells
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