SEARCH · PubMed Health

Results for “Extracellular Matrix”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources

PubMed2006

Platelet-rich plasma (PRP) stimulates the extracellular matrix metabolism of porcine nucleus pulposus and anulus fibrosus cells cultured in alginate beads.

STUDY DESIGN: In vitro assessment of the effects of platelet-rich plasma on the extracellular matrix metabolism of porcine intervertebral disc cells. OBJECTIVES: To determine whether platelet-rich plasma is effective in stimulating cell proliferation and extracellular matrix metabolism by porcine disc cells cultured in alginate beads. SUMMARY OF BACKGROUND DATA: Platelet-rich plasma is used to accelerate wound healing and tissue regeneration. Activated platelets release multiple growth factors that regulate cell proliferation, differentiation, and morphogenesis. Individual growth factors present in platelet-rich plasma have been demonstrated to affect the metabolism of intervertebral disc cells. METHODS: Platelet-poor and platelet-rich plasma was isolated from fresh porcine blood using a commercially available platelet concentration system. After preculture for 7 days and serum starvation for 24 hours, the beads containing nucleus pulposus and anulus fibrosus cells were then cultured for another 72 hours in serum-free medium, 10% fetal bovine serum, 10% platelet-poor plasma, or 10% platelet-rich plasma. The synthesis of proteoglycans and collagen, the accumulation of proteoglycans, and the DNA content were biochemically assessed. RESULTS: Platelet-rich plasma had a mild stimulatory effect on cell proliferation of intervertebral disc cells. Platelet-rich plasma treatment significantly upregulated proteoglycan and collagen synthesis and proteoglycan accumulation when compared with platelet-poor plasma. CONCLUSIONS: Platelet-rich plasma was effective in stimulating cell proliferation and extracellular matrix metabolism. The response to platelet-rich plasma was greater in the case of anulus fibrosus cells than of nucleuspulposus cells. The local administration of platelet-rich plasma might stimulate intervertebral disc repair. In addition, given the risks of using animal serum for tissue engineering, autologous blood may gain favor as a source of growth factors and serum supplements needed for stimulating cells to engineer intervertebral disc tissues.

Animals↗

PubMed2002

Effect of transforming growth factor-beta(2) on extracellular matrix synthesis in bovine trabecular meshwork cells.

OBJECTIVE: To investigate the effect of transforming growth factor-beta(2) (TGF-beta(2)) in human aqueous humor on extracellular matrix synthesis in cultured bovine trabecular meshwork cells. METHODS: Cultured 3-5 passage bovine trabecular meshwork cells were divided into control group and experimental group. After treated with 0 ng/L (control), 0.32 x 10(3) ng/L, 1.00 x 10(3) ng/L, 3.20 x 10(3) ng/L TGF-beta(2) for 48 h, collagen, fibronectin and hyaluronic acid synthesis in bovine trabecular meshwork cells were examined respectively by (3)H-proline incorportion and liquid scintillation technique, enzyme linked immunosorbent assay (ELISA) and radioimmunoassay (RIA). RESULTS: In comparison with the control group, TGF-beta(2) significantly promoted the synthesis of collagen at 0.32 x 10(3) ng/L (P < 0.05), 1.00 x 10(3) ng/L (P < 0.01), 3.20 x 10(3) ng/L (P < 0.01), (3)H-proline incorporation increased in a concentration-dependent manner; and 1.00 x 10(3) ng/L (P < 0.05), 3.20 x 10(3) ng/L (P < 0.01) TGF-beta(2) significantly promoted the synthesis of fibronectin in cultured bovine trabecular meshwork cells. 1.00 x 10(3) ng/L (P < 0.01) and 3.20 x 10(3) ng/L (P < 0.01) TGF-beta(2) significantly inhibited the synthesis of hyaluronic acid in the cultured cells. CONCLUSION: The data suggest that TGF-beta(2) play important roles in extracellular matrix age-related changes of normal trabecular meshwork and abnormal deposition of the extracellular matrix in the trabecular meshwork, especially the juxtacanalicular tissue of primary open-angle glaucoma patients.

Animals↗

PubMed1994

Membrane fluidity and adherence to extracellular matrix components are related to blast cell count in acute myeloid leukemia.

The level of blast cells in peripheral blood in acute myeloid leukemia (AML) varies in individual patients. The bone marrow egress of hematopoietic cells is an unclear phenomenon in which cell deformability and cytoadhesion to the extracellular matrix are involved. One component of deformability is the membrane fluidity. Using fluorescence polarization, we have studied the fluidity of blast cell membranes from 22 AML patients. This membrane was found to be highly fluid and a statistically significant correlation was found between the increase in membrane fluidity and the number of blast cells in the blood. Studying interaction between blast cells and several components of bone marrow stroma, we found adhesion to fibronectin and fibroblastic extracellular matrix. Adhesion to the extracellular matrix was inversally correlated to the level of blast cells in the blood. The observed increase in membrane fluidity and reduction of adhesion to bone marrow stroma may result in an increase of blast cells egress in AML.

Acute Disease↗

PubMed1996

[The effect of microtubules on the morphology of a fibroblast monolayer and its extracellular matrix].

The aim of this investigation was to study the effect of microtubule-specific drugs, taxol and colcemid, on the morphology of cytoskeletal systems and distribution of cell-associated extracellular matrix in dense cultures of fibroblasts. Immunomorphological examination of human 6-8 days old cultures revealed that microtubules, actin and vimentin filaments and filaments of extracellular matrix: fibronectin and tenascin-preferentially oriented in parallel with long axes of cell bodies. Depolymerization of microtubular system by colcemid and its disorganization by taxol lead to rapid and drastic changes in morphology of all cytoskeletal systems and in the organization of matrix network: fibronectin and tenascin filaments became disordered and, in particular, lost any orientation. These data show that microtubular system controls the morphological organization, and not only of two intracellular cytoskeletal systems, but also of extracellular matrix structures.

Actin Cytoskeleton↗

PubMed1996

Differences in submicroscopic structure of the extracellular matrix of canine femoral and tibial condylar articular cartilages as revealed by polarization microscopical analysis.

The submicroscopic orientation patterns of sulfated glycosaminoglycan side chains of proteoglycan molecules and collagen fibrils were compared in different extracellular matrix areas of femoral and tibial articular cartilages of young adult beagle dogs using qualitative and quantitative polarization microscopic analytical methods. Paraffin sections were cut perpendicularly to the articular surfaces from the femoral and tibial condyles and stained. Picrosirius red F38 staining combined with an antecedent digestion with testicular hyaluronidase was used to enhance the optical anisotropy of collagen. Birefringence of sulfated glycosaminoglycan molecules was selectively amplified by a combination of carboxymethylation with CH3I and a subsequent staining with toluidine blue. The specimens were analysed in a polarization microscope equipped with compensator plates, and retardation values of birefringence were determined in territorial and interterritorial matrix areas of different zones using monochromatic plane polarized light. It was found that besides some similarities there were significant differences in the submicroscopic organization of extracellular matrix between femoral and tibial articular cartilages. Common structural features of the femoral and tibial cartilages were the sulfated glycosaminoglycans and collagen fibrils which were circularly oriented in the territorial matrix, and these components were longitudinally arranged within the trabeculae of the interterritorial matrix. Furthermore, the territorial matrix was a more densely packed structure than the interterritorial matrix. Our results revealed the following major differences between the two cartilages: The degree of orientation of sulfated glycosaminoglycans was higher in the femoral cartilage matrix areas as compared to the identical structures of the tibial cartilage; the collagen structure was more densely packed in the interterritorial matrix of the superficial and mineralization zones of the femoral cartilage than in the tibial cartilage, and except for the zone of mineralization, the degree of collagen orientation was higher in the territorial matrix of the femoral than the tibial cartilage. These findings suggest that the extracellular matrix of femoral condylar cartilage has a more densely packed molecular structure than the softer tibial cartilage matrix. This structural difference may have an influence on the pathogenesis of diseases involving articular cartilage.

Animals↗

PubMed1986

Extracellular matrix of the human optic nerve head.

Double-antibody immunofluorescent studies of sectioned human optic nerve head indicated the marked presence of collagen type IV and laminin in the extracellular matrix of the lamina cribrosa. These macromolecules were layered transversely across the nerve fascicles and appeared to constitute the cribriform plates. Relatively little collagen types III and I were present in the extracellular matrix of this tissue and fibronectin was not detected in appreciable amounts. These results indicated that the lamina cribrosa contains a specialized extracellular matrix of the central nervous system made up of plates of material resembling basement membrane. The major macromolecular components of the lamina cribrosa do not resemble those of sclera.

Adult↗

PubMed2003

Expression of extracellular matrix markers in benign meningiomas.

Meningiomas have mesenchymal differentiation and studies have confirmed that meningiomas express intermediate filaments of both mesenchymal and epithelial types including vimentin and keratin. To further characterize their mesenchymal properties, particularly the role of factors requiring adhesion, extracellular matrix degradation, and migration, meningiomas were examined for a panel of extracellular matrix markers. Immunoreactivity to the matrix metalloproteinases, MMP-2 and MMP-9, and their tissue inhibitor, TIMP-1, and to an adhesion factor, galectin-3 were found in the majority of cases. The present study suggests that expression of these factors in benign meningiomas is ubiquitous and unrelated to tumor location. Therefore, these factors of the extracellular matrix may be potential targets of future therapy.

Adult↗

PubMed2001

Transmembrane crosstalk between the extracellular matrix--cytoskeleton crosstalk.

Integrin-mediated cell adhesions provide dynamic, bidirectional links between the extracellular matrix and the cytoskeleton. Besides having central roles in cell migration and morphogenesis, focal adhesions and related structures convey information across the cell membrane, to regulate extracellular-matrix assembly, cell proliferation, differentiation, and death. This review describes integrin functions, mechanosensors, molecular switches and signal-transduction pathways activated and integrated by adhesion, with a unifying theme being the importance of local physical forces.

Animals↗

PubMed1988

Acetylcholine receptor-aggregating proteins are associated with the extracellular matrix of many tissues in Torpedo.

The synaptic basal lamina, a component of extracellular matrix (ECM) in the synaptic cleft at the neuromuscular junction, directs the formation of new postsynaptic specializations, including the aggregation of acetylcholine receptors (AChRs), during muscle regeneration in adult animals. Although the molecular basis of this phenomenon is unknown, it is mimicked by AChR-aggregating proteins in ECM-enriched fractions from muscle and the synapse-rich electric organ of the ray Torpedo californica. Molecules immunologically similar to these proteins are concentrated in the synaptic basal lamina at neuromuscular junctions of the ray and frog. Here we demonstrate that immunologically, chemically, and functionally similar AChR-aggregating proteins are also associated with the ECM of several other tissues in Torpedo. Monoclonal antibodies against the AChR-aggregating proteins from electric organ intensely stained neuromuscular junctions and the ventral surfaces of electrocytes, structures with a high density of AChRs. However, they also labeled many other structures which have basal laminae, including the extrajunctional perimeters of skeletal muscle fibers, smooth and cardiac muscle cells, Schwann cell sheaths in peripheral nerves, walls of some blood vessels, and epithelial basement membranes in the gut, skin, and heart. Some structures with basal laminae did not stain with the antibodies; e.g., the dorsal surfaces of electrocytes. Bands of similar molecular weight were detected by the antibodies on Western blots of extracts of ECM-enriched fractions from electric organ and several other tissues. Proteins from all tissues examined, enriched from these extracts by affinity chromatography with the monoclonal antibodies, aggregated AChRs on cultured myotubes. Thus, similar AChR-aggregating proteins are associated with the extracellular matrix of many Torpedo tissues. The broad distribution of these proteins suggests they have functions in addition to AChR aggregation.

Agrin↗

PubMed1992

Pretranslational regulation of extracellular matrix macromolecules and collagenase expression in fibroblasts by mechanical forces.

In vivo, the extracellular matrix modulates the phenotype of the connective tissue cells both through its biochemical composition and the transfer of mechanical information. In this study, the mechanical effect was investigated in collagen gels populated by skin fibroblasts maintained under tension (bound lattices (BL)) compared with free retracting lattices (FL) and monolayer on plastic. The overall proteins and collagen synthesis of human skin fibroblasts, investigated by isotopic labeling, were decreased respectively by a factor of about 20 and 40 in FL compared with monolayers and increased by a factor of 4 and 6 in BL versus FL. As assayed by the degradation of [3H]collagen type I by trypsin-activated medium conditioned by fibroblasts under the three models of culture, collagenase activity was inversely regulated and increased in lattices when compared with monolayer culture. It was four times higher in FL than in BL. The steady-state level of mRNA coding for procollagen types I, III, and VI polypeptides, fibronectin, elastin, beta-actin, and procollagenase was determined by cDNA hybridization. The mRNA coding for beta-actin as well as for the various extracellular matrix macromolecules were increased in BL when compared with FL while the level of procollagenase mRNA was lower. These data demonstrate the existence of a modulation of the function of the fibroblasts performed by mechanical forces. This regulation operates, at least in part, at a pretranslational level.

Actins↗

PubMedDate not supplied

Culture of porcine spermatogonia: effects of purification of the germ cells, extracellular matrix and fetal calf serum on their survival and multiplication.

Initial studies to establish an in vitro system allowing survival and multiplication of porcine spermatogonia are described. Purified spermatogonia from 3-week-old pigs were cultured for 9 days alone or in the presence of Sertoli cells in either control medium or in medium supplemented with 5%, fetal calf serum (FCS). Under either condition the number and the viability of the cells decreased with time. but both parameters were positively influenced by the presence of FCS. However, very few, if any, spermatogonia were able to take up BrdU under either condition. In another series of experiments, small fragments of seminiferous tubules from 3-week-old pigs were cultured in the presence of FCS, or seeded on an extracellular matrix. Under these conditions the number of cells decreased between day 0 and day 2 or day 5, then it remained roughly constant until the end of the culture. The number of spermatogonia decreased 2.5 fold during the two-week culture period. Spermatogonia were able to incorporate BrdU until the end of the experiment. The number of BrdU-labeled spermatogonia was higher when tubule-segments were seeded on an extracellular matrix. Then, the effects of the association of FCS and extracellular matrix were tested. The number of spermatogonia, during the whole culture period, was higher in serum-containing cultures than in serum-free cultures. As for the number of spermatogonia able to incorporate BrdU at -different days, is decreased 3 fold between day 2 and 14 irrespective of the culture conditions. By contrast, the number of spermatogonia, labeled with BrdU between day 1 and 2, measured on days 5 to 14 of culture, was higher in serum-containing cultures. Finally, the number of spermatogonia labeled between day 1 and 2 was higher from day 5 onward than the number of spermatogonia able to take up BrdU between days 4 and 13. Taken together, these results indicate that intercellular communication and extracellular matrix are important for spermatogonia multiplication and that FCS promotes the survival of spermatogonia under in vitro conditions.

Animals↗

PubMed1994

Assembly of the tendon extracellular matrix during development.

The assembly of the collagenous extracellular matrix during tendon development was studied to determine the mechanisms involved in collagen fibril growth. Developing avian metatarsal tendons were studied using structural, immunochemical and biochemical approaches. Tendon fibroblasts were shown to establish a hierarchy of extracellular compartments associated with fibrils, bundles, and macroaggregates during development. These distinct domains provide a mechanism for the fibroblast to influence the extracellular steps in matrix assembly. A discontinuous fibrillar matrix was assembled and fibril segments approximately 10-20 microns long were deposited into bundles by the 14 d embryo fibroblasts. The fibril segment is a normal assembly intermediate, permitting orderly linear, lateral and intercalatory development and growth. A lateral and/or linear fusion of segments may be responsible for the formation of mature continuous fibrils. Fibril segments were isolated from 12-18 d chick embryo metatarsal tendons. Homogenisation almost completely disrupted the 12-15 d tendons. Transmission electron microscopy demonstrated intact segments. Between d 12 and 15 of development, mean segment length increased from approximately 22 to 33 microns. The incremental increase in length with development indicates a limited linear fusion of segments which is supported by morphological examination. At 16 d, there was a significant decrease in segment extractability and by 17-18 d, intact segments were unextractable. Mean segment lengths were 37 microns and > 70 microns for 16 and 17 d tendons respectively. During this period, fibril diameter also increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1996

Chondrocyte cultures express matrix metalloproteinase mRNA and immunoreactive protein; stromelysin-1 and 72 kDa gelatinase are localized in extracellular matrix vesicles.

Previous studies have shown that costochondral cartilage cell cultures produce extracellular matrix vesicles which contain metalloproteinase activity. In the present study, we examined whether two matrix metalloproteinases (MMPs) known to be present in cartilage, stromelysin-1 and 72 kDa gelatinase, are expressed by fourth passage resting zone and growth zone costochondral chondrocytes and whether they are specifically incorporated into matrix vesicles produced by the cells. We also examined whether the cells synthesize tissue inhibitor of metalloproteinase-1 and -2 (TIMP-1 and TIMP-2). Oligonucleotide primers for stromelysin-1, 72 kDa gelatinase, tissue inhibitor of metalloproteinases-1 and -2 (TIMP-1 and TIMP-2), and GAPDH were synthesized and optimized for use in the reverse transcription-polymerase chain reaction (RT-PCR). It was found that both resting zone and growth zone chondrocytes produced mRNA for both MMPs and the two TIMPs. Further, immunostaining of cell layers with antibodies to 72 kDa gelatinase and stromelysin-1 showed that both cell types produced these MMPs in culture. Substrate gel electrophoresis and Western analysis were used to characterize MMP activity in matrix vesicles, media vesicles, or plasma membranes as well as in conditioned media produced by the chondrocyte cultures. It was found that matrix vesicles but not plasma membranes or media vesicles were selectively enriched in stromelysin-1. Also, 72 kDa gelatinase was found in matrix vesicles, but to a lesser extent than seen in media vesicles. The relative activity of each enzyme detected was cell maturation-dependent. No MMP activity was detected in conditioned media produced by either cell type. The results of this study show that MMPs are expressed by resting zone and growth zone chondrocytes in culture and differentially distributed among three different membrane compartments. This suggests that, in addition to the well-known activators and inhibitors of MMP activity in the matrix, differential membrane distribution may enable more precise control over the site, rate, and extent of matrix degradation by the cell.

Animals↗

PubMed1999

The extracellular matrix of rat pacinian corpuscles: an analysis of its fine structure.

The Pacinian corpuscle consists of a sensory axon terminal that is enveloped by two different structures, the inner core and the capsule. Since proteoglycans are extremely water soluble and are extracted by conventional methods for electron microscopy, the current picture of the structural composition of the extracellular matrix in the inner core and the capsule of the Pacinian corpuscle is incomplete. To study the structural composition of the extracellular matrix of the Pacinian corpuscles, cationic dyes (ruthenium red, alcian blue, acridine orange) and tannic acid were applied simultaneously with the aldehyde fixation. The interosseal Pacinian corpuscles of the rat were fixed either in 2% formaldehyde and 1.5% glutaraldehyde, with the addition of one of these cationic dyes or, in Zamboni's fixative, with tannic acid added. The cationic dyes and tannic acid revealed a different structural pattern of proteoglycans in the extracellular matrix in the inner core and in the capsule of the rat Pacinian corpuscles. The inner core surrounding the sensory axon terminal is a compartment containing proteoglycans that were distributed not only in the extracellular matrix but also in the cytoplasm of the lamellae. In addition, this excitable domain was separated from the capsular fluid by a thick layer of proteoglycans on its surface. An enlarged interlamellar space of the capsule contained large amounts of proteoglycans that were removed by digestion with chondroitinase-ABC. Ruthenium red and alcian blue provided only electron dense granules, probably corresponding to collapsed monomeric proteoglycan molecules. Acridine orange and tannic acid preserved proteoglycans very well and made it possible to visualize them as "bottlebrush" structures in the electron microscope. These results show that the inner core and the capsule of rat Pacinian corpuscles have different structural patterns of proteoglycans, which are probably involved in different functions.

Acridine Orange↗

PubMedDate not supplied

Extracellular matrix and its interactions in the diabetic kidney: a molecular biological approach.

Increased extracellular matrix (ECM) is the ultrastructural hallmark of diabetic microangiopathy. Its accumulation within the kidney is directly linked to the clinical manifestations of diabetic nephropathy, namely proteinuria and declining renal function. The pathogenesis of ECM changes in diabetes is not well understood, but is likely to involve interaction between cells, growth factors, structural proteins, and cell receptors for these molecules. Molecular biological techniques may offer the necessary tools for gaining insight into the pathogenetic processes that eventually lead to renal failure in diabetes.

Animals↗

PubMed1997

Proliferation and extracellular matrix production by human infragenicular smooth muscle cells in response to interleukin-1 beta.

PURPOSE: Atherosclerotic peripheral vascular disease commonly involves the infragenicular arterial tree. Our study evaluated the effect of interleukin (IL)-1 beta on the proliferation of vascular smooth muscle cells (VSMCs) derived from atherosclerotic infragenicular arteries of human subjects who underwent below-knee amputation, as well as the role of IL-1 beta in VSMCs' production of extracellular matrix components, substances that are important in the transformation of VSMCs from the contractile to the synthetic phenotype. This transformation to the synthetic phenotype is an important step in the formation of the atherosclerotic lesion. METHODS: Cultures were identified as being of smooth muscle origin through staining with the cytoskeletal marker, alpha-smooth muscle actin. Proliferation assays were performed by seeding confluent cultures of passages 4 to 7 into six-well plates at 10,000 cells per well. After serum starvation, samples were incubated with IL-1 beta (1 ng/ml). Cell number was determined on a daily basis. To study extracellular matrix production, cells were propagated in tissue culture chamber slides in the absence or presence of growth media containing IL-1 beta. After fixation with 100% methanol, each sample was stained with a primary antibody specific for an extracellular matrix component. After staining with the fluorescein-tagged secondary antibody, each sample was examined using immunofluorescent microscopic examination. RESULTS: The results of our proliferation assays showed that IL-1 beta caused a significant increase in the proliferation of VSMCs at 24, 48, 72, and 96 hours (p < or = 0.003 when comparing IL-1 beta-treated samples with control specimens at each time period using unpaired t test). The number of IL-1 beta-treated cells at 96 hours was double the number present in the control samples (16,033 +/- 238 vs 8102 +/- 824). When compared with control samples, IL-1 beta was found to affect the production of extracellular matrix proteins by infragenicular VSMCs. IL-1 beta caused an increase in the production of fibronectin, a decrease in the production of laminin, and no change in the production of collagen type IV. CONCLUSIONS: These results suggest that interleukin-1 beta acts as a potent stimulant of the proliferation of human infragenicular VSMCs. IL-1 beta also acts to augment the production of fibronectin by these cells. Fibronectin has been implicated in the phenotypic transformation of VSMCs from the contractile to the synthetic state. Therefore, IL-1 beta may serve as an important regulatory factor in the development of atherosclerosis by stimulating the proliferation of VSMCs and their transformation to the synthetic state, two important steps in the formation of the atherosclerotic lesion.

Arteries↗

PubMed1992

Enzymatic activity and in vivo distribution of 5'-nucleotidase, an extracellular matrix binding glycoprotein, during the development of chicken striated muscle.

The ecto-enzyme 5'-nucleotidase isolated from chicken gizzard has previously been shown to be a potent ligand of two glycoproteins of the extracellular matrix, namely fibronectin and laminin. Using immunofluorescent labeling techniques we observed that 5'-nucleotidase codistributed with laminin during the development of chicken striated muscle. In contrast, ecto-5'-nucleotidase was only faintly detectable on cells surrounded by a matrix expressing high levels of fibronectin. This distribution pattern distinguished 5'-nucleotidase from the pluripotent extracellular matrix receptors, chicken beta 1-integrins, which are expressed equally well in muscle and connective tissue. In addition, the specific activity of striated muscle ecto-5'-nucleotidase was stable during development and increased markedly posthatching. At each age considered, this specific activity corresponded to an 80-kDa enzyme which was inhibited by alpha,beta-methyleneadenosine diphosphate or by a monoclonal antibody directed against the smooth muscle isoform of the enzyme. Previous in vitro studies have revealed that 5'-nucleotidase is involved in the spreading of various mesenchyme-derived cells, such as chicken embryonic fibroblasts and myoblasts, on a laminin substrate. A prerequisite to examining a potential in vivo role for 5'-nucleotidase as an extracellular matrix ligand was to study its distribution. In adult muscle, 5'-nucleotidase displayed a more restricted distribution than in embryo. Results show that, in vivo, 5'-nucleotidase is revealed by immunofluorescent labeling using poly- and monoclonal antibodies to chicken gizzard 5'-nucleotidase in two structures, the costameres and myotendinous junctions, which are closely related to the focal adhesion sites observed in cell culture.

5'-Nucleotidase↗

PubMed1983

A perfusion chamber developed to investigate platelet interaction in flowing blood with human vessel wall cells, their extracellular matrix, and purified components.

A flat perfusion chamber was developed to study the interaction of blood platelets in flowing blood with cultured human vessel wall cells, their connective tissue matrix, and isolated connective tissue components at defined shear rate conditions. A cover slip covered with endothelial cells or extracellular matrix components was introduced into the chamber. Laser-Doppler velocimetry showed a symmetrical flow profile at flow rates between 50 and 150 ml/min (wall shear rate 300 to 1100 sec-1). Platelet deposition was estimated by using blood platelets labeled with indium-111 or by a morphometric method. Blood platelets did not adhere to endothelial cells at wall shear rates of 765 sec-1 and the endothelial cells remained attached for at least 10 min of perfusion. In preconfluent cultures of endothelial cells, blood platelets adhered to extracellular material in areas between the cells. Removal of endothelial cells by treatment with 0.5% Triton X-100 induced increased platelet adherence with a preference for certain, as yet unidentified, fibrillar structures of the extracellular matrix. Platelet adherence to equine collagen was also studied after coating the cover slips by spraying of small collagen droplets followed by air drying. Platelet adherence and the subsequent platelet aggregate formation occurred predominantly along visible collagen fibers. These studies showed that this perfusion chamber has a laminar and symmetrical flow allowing qualitative and quantitative investigation of platelet interaction with endothelial cells, their extracellular matrix, and pure connective tissue components. A variety of wall shear rates and exposure times can be applied at controlled conditions without removing cells or extracellular material.

Animals↗