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Results for “Extracellular Matrix”

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PubMed2003

Membrane type I matrix metalloproteinase usurps tumor growth control imposed by the three-dimensional extracellular matrix.

Cancer cells are able to proliferate at accelerated rates within the confines of a three-dimensional (3D) extracellular matrix (ECM) that is rich in type I collagen. The mechanisms used by tumor cells to circumvent endogenous antigrowth signals have yet to be clearly defined. We find that the matrix metalloproteinase, MT1-MMP, confers tumor cells with a distinct 3D growth advantage in vitro and in vivo. The replicative advantage conferred by MT1-MMP requires pericellular proteolysis of the ECM, as proliferation is fully suppressed when tumor cells are suspended in 3D gels of protease-resistant collagen. In the absence of proteolysis, tumor cells embedded in physiologically relevant ECM matrices are trapped in a compact, spherical configuration and unable to undergo changes in cell shape or cytoskeletal reorganization required for 3D growth. These observations identify MT1-MMP as a tumor-derived growth factor that regulates proliferation by controlling cell geometry within the confines of the 3D ECM.

Animals↗

PubMed1995

Postembedding colloidal-gold immunocytochemistry of noncollagenous extracellular matrix proteins in mineralized tissues.

Immunocytochemistry is a powerful tool for investigating protein secretion, extracellular matrix assembly, and cell-matrix and matrix-matrix/mineral relationships. When applied to the tissues of bones (bone and calcified cartilage) and teeth (dentin, cementum, and enamel), where calcium phosphate-containing extracellular matrices are the predominant structural component related to their weight-bearing and masticatory roles, respectively, data from immunocytochemical studies have been prominent in advancing our understanding of mineralized tissue modeling and remodeling. The present review on the application of postembedding, colloidal-gold immunocytochemistry to mineralized tissues focuses on the advantages of this approach and relates them to conceptual, theoretical, and experimental data currently available discussing matrix-mineral interactions and extracellular matrix formation and turnover in these tissues. More specifically, data are summarized regarding the distribution and role of noncollagenous proteins in different mineralized tissues, particularly in the context of how they interface with mineral, and how this relationship might be affected by the various tissue-processing steps and immunocytochemical strategies commonly implemented to examine the distribution and function of tissue proteins. Furthermore, a technical discussion is presented that outlines several different possibilities for epitope exposure in mineralized tissues during preparation of thin sections for transmission electron microscopy. Cell biological concepts of protein secretion by cells of the mineralized tissues, and subsequent extracellular matrix assembly and organization, are illustrated by examples of high-resolution, colloidal-gold immunolabeling for osteopontin, bone sialoprotein, and osteocalcin in the collagen-based mineralized tissues and for enamel protein (amelogenin) in enamel.

Animals↗

PubMed2006

Tenectin, a novel extracellular matrix protein expressed during Drosophila melanogaster embryonic development.

During Drosophila embryonic development, various morphogenetic processes require the remodeling of the extracellular matrix. In a previous study, we have identified and characterized a cDNA encoding a novel putative extracellular matrix protein named tenebrin, in the beetle Tenebrio molitor. Here, we examine the expression of the Drosophila ortholog, referred to as Tenectin (Tnc), during embryonic development. Tnc is expressed in the majority of tissues of neuroectodermic origin such as hindgut, foregut, tracheal system, anal plate, and CNS. In the CNS, the Tnc transcript is restricted to a few cells, whereas the protein is located in the dorsal part of the axonal tracts. In the hindgut and the trachea, Tnc protein is expressed on the apical pole of the cells. Tnc is an extracellular matrix protein secreted in a polarized way in different organs of Drosophila embryos.

Animals↗

PubMed1990

Fibronectin-rich fibrillar extracellular matrix controls cell migration during amphibian gastrulation.

We have reviewed the evidence supporting the notion that the fibrillar extracellular matrix on the basal surface of the blastocoel roof in amphibian embryos directs and guides mesodermal cell migration during gastrulation. Based on extensive experimental evidence in several different systems, we conclude the following: (i) the fibrillar extracellular matrix contains fibronectin (FN) and laminin. (ii) The fibrils are oriented in such a way as to promote directional migration of mesodermal cells during migration. (iii) We have used several different probes to disrupt the interaction between migrating mesodermal cells and the fibrillar extracellular matrix. These probes include: (a) nucleocytoplasmic and interspecific hybridization. Such embryos have defects in FN synthesis and gastrulation. (b) Fab' fragments of anti-FN and anti-integrin VLA-5 IgGs prohibit mesodermal cell adhesion both in vitro and in vivo and gastrulation is arrested. (c) Peptides containing the RGDS sequence specifically inhibit interactions between migrating mesodermal cells and the FN-fibrillar matrix. (d) Tenascin blocks cell adhesion to FN in vitro and gastrulation in vivo. (e) Antibodies against the cytoplasmic domain of beta 1 integrin, when injected into blastomeres, prevent FN-fibrillogenesis in progeny of injected blastomeres and delay mesodermal cell migration selectively in the progeny of injected blastomeres but not in the uninjected blastomere progeny.

Amphibians↗

PubMed1990

Molecules of the extracellular matrix: potential role of collagens and glycoproteins in intestinal adaptation.

The extracellular matrix plays a fundamental role in modulating cellular growth, differentiation and migration. Therefore it merits major attention in studies of adaptation. The five types of collagen and several extracellular glycoproteins hitherto found in the intestine are biochemically well defined. They form supramolecular complexes and via specific domains interact with integrins, a specialized class of transmembrane glycoproteins. The integrins transfer signals to the cytoskeleton and probably to the nucleus of the cell. The extracellular matrix and its cellular receptors are well orchestrated with several cell types, the immune system and soluble mediators and hormones, thus being indispensable members of a complicated regulatory network operative in adaptation.

Adaptation, Physiological↗

PubMed2004

Clinicopathological study of the expression of syndecan-1 in invasive breast carcinomas. correlation with extracellular matrix components.

Syndecan-1, a cell surface proteoglycan found predominantly on epithelia of mature tissues, binds both extracellular matrix (ECM) components and basic fibroblast growth factor (bFGF) and is implicated in the restriction of growth and invasiveness of neoplastic cells, as it induces the adhesion capacity of neoplastic cells with the stroma. In this study we investigated breast carcinomas for the immunohistochemical expression of syndecan-1 protein and these results were assessed in relation to clinicopathological parameters, in order to clarify its prognostic value. The possible relationship with hormone receptors content, p53, cell proliferation markers, and extracellular matrix components was also estimated. Tissue sections from 102 breast carcinomas were used and immunostainings were performed on formalin-fixed, paraffin-embedded tissue sections by the labelled streptavidin avidin biotin (LSAB) method. High expression levels were observed, as 75/102 (73.5%) cases expressed immunoreactivity in more than 80% of neoplastic cells, while 67/102 (65.7%) exhibited high staining intensity. The survival analysis showed an increased mortality risk associated with high syndecan-1 staining intensity with borderline significance (p=0.041). In addition, there was a strong negative correlation between syndecan-1 protein expression and ECM, specifically collagen IV (p=0.026) and tenascin (p=0.0067). The results of the present study show the implication of this protein in the remodeling of breast cancer tissue, through the interaction with other extracellular matrix components, probably influences the tumour progression.

Avidin↗

PubMed1980

Morphological appearance, growth behavior and migratory activity of human tumor cells maintained on extracellular matrix versus plastic.

Growth of human tumor cells (hepatocarcinoma, Ewing's sarcoma) on an extracellular matrix (ECM) produced by bovine corneal endothelial cells is associated with the adoption of a morphological appearance and growth properties that are not expressed when the cells are maintained on plastic. Within minutes after seeding cell aggregates onto an ECM, the aggregates attached firmly. Active cell migration leading to the formation of flattened and nonoverlapping cell clusters was subsequently observed. In contrast, no firm attachment, migratory activity or disorganization of cell aggregates was observed when the same cells were maintained on plastic. Cells seeded on ECM, instead of growing as floating or loosely attached aggregates, formed a cell monolayer composed of firmly attached, highly flattened and closely apposed epithelioid-like cells. Cell overlapping and subsequent detachment were observed only late at confluence. Cells maintained on ECM had a higher growth rate as well as a lower serum requirement than those maintained on plastic. These results demonstrate that the phenotypic expression as well as the proliferation of tumor cells can be modulated by their adhesive interaction with the extracellular matrix. Both tumor cells and normal cells of epithelial origin are more likely to resemble their in vivo counterparts when maintained on extracellular matrix than on plastic, and when so maintained can therefore provide a better model for oncogenic studies.

Cell Adhesion↗

PubMed1985

Dental cell interaction with extracellular-matrix constituents: type-I collagen and fibronectin.

It has been suggested that, during odontoblast differentiation, the extracellular matrix present at the epitheliomesenchymal junction modulates the activity of the cytoskeleton by means of membrane constituents (proteins, proteoglycans or gangliosides). To investigate this, we studied the interaction of iodinated fibronectin and type-I collagen with dissociated dental tissues and with membrane proteins prepared from these tissues. Isolated dental papillae and enamel organs were cultured for increasing periods of time in the presence of iodinated proteins. Fibronectin and type-I collagen were preferentially bound to dental papillae; however, after 6 h of incubation, fibronectin no longer interacted with the dental papillae, and the bound radioactivity was released. In the meantime, de novo synthesized fibronectin was deposited in the extracellular matrix of the dental papillae. Membrane proteins were prepared from isolated enamel organs and dental papillae. After sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis, these proteins were transferred to nitrocellulose by electroblotting and then incubated in the presence of either 125I-labelled fibronectin or 125I-labelled type-I collagen. Autoradiography confirmed the preferential interaction of fibronectin with the dental papilla. Fibronectin interacted with three high-molecular-weight proteins (Mr, 145,000, 154,000 and 185,000), which were not detected when membranes were prepared from enamel organs. Under the same conditions, type-I collagen did not interact with membrane proteins. The known interaction of type-I collagen with the plasma membrane of dental-papilla cells might be mediated either by another constituent of the extracellular matrix or by cell-surface-associated proteoglycans.

Animals↗

PubMed1990

All-trans retinoic acid stimulates growth and extracellular matrix production in growth-inhibited cultured human skin fibroblasts.

All-trans retinoic acid was examined for effects on human dermal fibroblast proliferation and for effects on fibroblast production and expression of non-collagenous and collagenous components of the extracellular matrix in vitro. Fibroblast proliferation was blocked when the cells were cultured in the presence of a serum-free culture medium containing epidermal growth factor, hydrocortisone, insulin, ethanolamine, phosphoethanolamine, and bovine pituitary extract as growth supplements and 0.15 mM Ca++. This level of extracellular Ca++ is lower than that needed to support fibroblast growth. Under these conditions, growth was stimulated by all-trans retinoic acid. Proliferation was also stimulated in the same basal medium without the growth supplements. Growth-promoting concentrations of all-trans retinoic acid ranged from 0.5-2.0 micrograms/ml (1.7-6.6 X 10(-6) M). Stimulation of proliferation was not seen at higher or lower concentrations. Concentrations of all-trans retinoic acid that stimulated proliferation also induced increased production of fibronectin as indicated by biosynthetic labeling/immunoprecipitation and by enzyme-linked immunosorbent assay. Increased production was associated with increased staining for fibronectin in the extracellular matrix. Increased production of two other non-collagenous extracellular matrix component, i.e., thrombospondin and laminin, also occurred in all-trans retinoic acid-treated cells. At 0.5 micrograms/ml, all-trans retinoic acid also stimulated production of type I collagen by the dermal fibroblasts, but at higher concentrations (2.5 micrograms/ml) production of type I collagen was inhibited. These data indicate that all-trans retinoic acid can induce changes in dermal fibroblasts in vitro (i.e., increased proliferation and extracellular matrix production) that mimic the major changes seen in the dermis after topical treatment with this agent.

Cell Division↗

PubMed1991

Gene expression and extracellular matrix ultrastructure of a mineralizing chondrocyte cell culture system.

Conditions were defined for promoting cell growth, hypertrophy, and extracellular matrix mineralization of a culture system derived from embryonic chick vertebral chondrocytes. Ascorbic acid supplementation by itself led to the hypertrophic phenotype as assessed by respective 10- and 15-fold increases in alkaline phosphatase enzyme activity and type X synthesis. Maximal extracellular matrix mineralization was obtained, however, when cultures were grown in a nutrient-enriched medium supplemented with both ascorbic acid and 20 mM beta-glycerophosphate. Temporal studies over a 3-wk period showed a 3-4-fold increase in DNA accompanied by a nearly constant DNA to protein ratio. In this period, total collagen increased from 3 to 20% of the cell layer protein; total calcium and phosphorus contents increased 15-20-fold. Proteoglycan synthesis was maximal until day 12 but thereafter showed a fourfold decrease. In contrast, total collagen synthesis showed a greater than 10-fold increase until day 18, a result suggesting that collagen synthesis was replacing proteoglycan synthesis during cellular hypertrophy. Separate analysis of individual collagen types demonstrated a low level of type I collagen synthesis throughout the 21-d time course. Collagen types II and X synthesis increased during the first 2 wk of culture; thereafter, collagen type II synthesis decreased while collagen type X synthesis continued to rise. Type IX synthesis remained at undetectable levels throughout the time course. The levels of collagen types I, II, IX, and X mRNA and the large proteoglycan core protein mRNA paralleled their levels of synthesis, data indicating pretranslational control of synthesis. Ultrastructural examination revealed cellular and extracellular morphology similar to that for a developing hypertrophic phenotype in vivo. Chondrocytes in lacunae were surrounded by a well-formed extracellular matrix of randomly distributed collagen type II fibrils (approximately 20-nm diam) and extensive proteoglycan. Numerous vesicular structures could be detected. Cultures mineralized reproducibly and crystals were located in extracellular matrices, principally associated with collagen fibrils. There was no clear evidence of mineral association with extracellular vesicles. The mineral was composed of calcium and phosphorus on electron probe microanalysis and was identified as a very poorly crystalline hydroxyapatite on electron diffraction. In summary, these data suggest that this culture system consists of chondrocytes which undergo differentiation in vitro as assessed by their elevated levels of alkaline phosphatase and type X collagen and their ultrastructural appearance.(ABSTRACT TRUNCATED AT 400 WORDS)

Alkaline Phosphatase↗

PubMed1990

The role of extracellular matrix in the morphogenesis and differentiation of salivary glands.

The processes of morphogenesis and cytodifferentiation are partially linked, independently regulated processes. The full expression of both processes is modulated or controlled, at least in part, by components of the extracellular matrix. This paper reviews the body of work that demonstrates a role for epithelial-mesenchymal interactions and various extracellular matrix molecules in the induction, control, and maintenance of salivary gland morphogenesis and cytodifferentiation. In addition, new, preliminary information which further elucidates the role of laminin and type IV collagen in the processes of morphogenesis and cytodifferentiation is presented. With regard to the role of extracellular matrix molecules in the regulation of salivary gland morphogenesis and cytodifferentiation, it appears that types I, III, and IV collagen, laminin, and chondroitin sulfate proteoglycan play roles in the control of glandular morphogenesis. With the exception of type IV collagen, these molecules do not appear to be involved in the regulation of cytodifferentiation of salivary gland secretory cells. On the other hand, of the extracellular matrix molecules tested so far, only type IV collagen appears to play a role in the regulation of salivary gland secretory cell differentiation.

Animals↗

PubMed2003

Rapamycin has no effect on fibrosis-associated gene expression or extracellular matrix accumulation when administered to animals with established or early allograft vasculopathy.

BACKGROUND: Most patients with functioning heart transplants have established and progressive chronic allograft vasculopathy, a fibroproliferative process for which there is no effective treatment. Coronary artery disease is characterized by histologic evidence of extracellular matrix accumulation (fibrosis). This study compares the effect of rapamycin administered to rats with established allograft vasculopathy on histologic indices of disease progression, extracellular matrix accumulation (fibrosis), and the expression of genes known to regulate extracellular matrix turnover in this model. METHODS: Lewis recipients of Fisher 344 rat thoracic to abdominal aorta transplants were administered rapamycin starting at 8, 12, and 16 weeks posttransplant or no treatment. Six grafts in each group were harvested at 24 weeks. Vascular remodeling and collagen accumulation (Sirius red) were measured by computerized histomorphometry of aortic sections. mRNA was extracted from frozen tissue, and the expression of fibrosis-associated genes was studied by means of semiquantitative reverse transcriptase-polymerase chain reaction. RESULTS: Rapamycin had no effect on the progression of early or established allograft vasculopathy with regard to intimal thickening, remodeling, extracellular matrix accumulation, or profibrotic gene expression, regardless of the time commenced. CONCLUSION: The attenuation of the fibroproliferative response in rodents by rapamycin is not seen if the onset of rapamycin therapy is delayed.

Animals↗

PubMed1995

Human skin mast cells express functional beta 1 integrins that mediate adhesion to extracellular matrix proteins.

We have evaluated the adhesion of human cutaneous mast cells to several components of the extracellular matrix (plasma fibronectin, laminin, collagen type I and IV) and studied whether these cells express the beta 1 integrins potentially involved in the adhesion to these proteins. Human skin mast cells (5.1 +/- 1.5% pure) spontaneously adhered to fibronectin and laminin (0.1 to 10 micrograms/ml) immobilized on plastic surfaces (e.g., 14 +/- 7.2% and 14 +/- 4.4% adhesion at 10 micrograms/ml, respectively). Similar results were obtained with a 90% pure mast cell preparation. In contrast, cutaneous mast cells did not adhere to collagen type I (1.6 +/- 0.5% adhesion) or type IV (1.2 +/- 0.8% adhesion). Control adhesion in BSA-coated wells was < 5%. Mast cell adhesion to fibronectin was optimal after an incubation period of 60 to 90 min (t1/2 = 28.2 +/- 6.2 min), whereas adhesion to laminin was faster (t1/2 = 10.1 +/- 1.2 min), being nearly optimal after a 15-min incubation period. Human skin mast cell adhesion to fibronectin and laminin was found to be dependent on the presence of divalent cations in the extracellular medium. Dual-color immunofluorescence and flow cytometry were used to evaluate whether human skin mast cells (51.3 +/- 3.9% pure) express beta 1 integrins that may mediate cell adhesion to extracellular matrix proteins. These mast cells were found to express VLA (very late Ag)-3 (75.3 +/- 35.6 specific fluorescence intensity) and, to lesser degree, VLA-4 and VLA-5 receptors (8.0 +/- 2.5 and 6.9 +/- 3.2 specific fluorescence intensity, respectively). In contrast, VLA-1, VLA-2, and VLA-6 integrins were not expressed significantly. mAb to VLA-3, VLA-4, and VLA-5 each inhibited by 70% skin mast cell adhesion to fibronectin. mAb to VLA-3 nearly abolished mast cells adhesion to laminin, whereas anti-VLA-4 and anti-VLA-5 were ineffective. Finally, immunosuppressant cyclosporin A (100 nM) and FK-506 (10 nM) significantly inhibited mast cell adhesion to both fibronectin and laminin (p < 0.05). Our data demonstrate that human skin mast cells spontaneously adhere to fibronectin and laminin, and that this adhesion is mediated by VLA-3, VLA-4, and/or VLA-5 integrins on these cells. Interactions between these beta 1 integrins and extracellular matrix proteins may be involved in perivascular tissue localization of human mast cells in vivo.

Cations, Divalent↗

PubMed1996

T-lymphocyte interactions with endothelium and extracellular matrix.

T-lymphocyte movement out of the bloodstream and into tissue is critical to the success of these cells in their role in immunosurveillance. This process involves interactions of the T-cell with endothelium as well as with extracellular matrix. Central to these interactions are a number of T-cell adhesion molecules and their endothelial and extracellular matrix ligands. The identification and functional characterization of adhesion molecules have been the subject of intensive research in recent years. We highlight here the latest developments in this rapidly expanding field as they pertain to T-cell interactions with endothelial cells and extracellular matrix components, including: (1) identification of adhesion molecule families, including the selectins, mucins, integrins, immunoglobulin superfamily members, and cadherins; (2) elucidation of the multi-step adhesion cascade that mediates the rolling, arrest, and eventual diapedesis of T-cells through the vascular endothelium into the surrounding tissue; (3) the changes in adhesion molecule expression that accompany T-cell maturation and activation, and the impact of those changes on T-cell migration; (4) the functional relevance of the extracellular matrix for T-cell function; and (5) the clinical relevance of adhesion molecules and the potential for targeting these molecules for the amelioration of immune-mediated diseases.

Animals↗

PubMed2006

Do extracellular-matrix-regulating enzymes play a role in cervical artery dissection?

BACKGROUND: An underlying extracellular matrix defect is suspected in patients with spontaneous cervical artery dissection (SCAD). We test the hypothesis that levels of matrix metalloproteinase (MMP) 2 and 9, and elastase, extracellular-matrix-regulating enzymes involved in the vascular wall remodeling process, are modified in SCAD. METHODS: The authors prospectively and consecutively recruited 47 patients with SCAD and 52 patients with an ischemic stroke from another cause in 2 centers, and measured their plasmatic level of MMP-2, MMP-9 and elastase 3 months after the vascular event. RESULTS: Patients with SCAD had a higher mean MMP-2 level compared with controls [379.2 (SD = 76.6) vs. 355.9 (75.1) ng/ml; p = 0.11] and had more frequently a high level of MMP-2 (>326 ng/ml) than controls (77.8 vs. 54.5%, p = 0.019). This association was stronger in patients with multiple dissection than single artery dissection or controls (84.6, 75.0 and 54.5%, respectively, p = 0.018). The levels of MMP-9 and elastase were similar in cases and controls, but more patients had a high level of these enzymes in the group with multiple dissections than in the group with single artery dissection or controls. CONCLUSION: Patients with SCAD have higher plasma levels of proteases, particularly MMP-2. The association is stronger in patients with multiple dissections.

Adult↗

PubMed1989

The expression of extracellular matrix and cytoskeleton in fused cells.

In the present paper results from our studies on the expression and regulation of the differentiated normal and transformed epithelial and fibroblastic phenotypes are reviewed. The expression of the extracellular matrix- and basement membrane-associated proteins, fibronectin and laminin, and different intermediate filament proteins were studied in different fused cells. Heterokaryons and cytoplasmic hybrids (cybrids) were formed by fusing normal or malignant epithelial cells with normal fibroblasts or malignant glial cells. No differences were observed in the expression of these phenotypic markers between unfused parental cells and the corresponding homokaryons. Thus, the fusion process itself does not cause changes in the expression of these phenotypic markers. In heterokaryons formed after fusion of normal or malignant epithelial cells with normal fibroblasts or malignant glial cells, two or even three different types of intermediate filaments could be co-expressed. Thus, no suppression of the expression of the various intermediate filaments is caused by the non-homologous parental cell. Expression of the extracellular matrix proteins, fibronectin and laminin, on the other hand, could be extinguished by cells and cytoplasts not expressing fibronectin matrix, such as transformed fibroblasts and HeLa cells. These results support the role of transacting regulatory factors controlling the expression of the different extracellular matrix proteins. Alternatively, the results can be explained by changes in the distribution and concentration of the extracellular matrix receptor proteins in the fused cells.

Animals↗

PubMed1993

Extracellular matrix and gene expression in mammary epithelium.

Correct cellular environment is required for the differentiation of many cell types. In mammary epithelium the extracellular matrix as well as lactogenic hormones cooperate to direct accurate tissue-specific gene expression. Current evidence indicates that the promoters of milk protein genes contain elements that are regulated by both extracellular matrix and hormones. Some mechanisms by which the extracellular matrix might control transcription are considered.

Animals↗

PubMed2003

Decellularization of rat aortic valve allografts reduces leaflet destruction and extracellular matrix remodeling.

OBJECTIVES: Decellularization of aortic valve allografts in advance of transplantation is a promising approach to overcome immune-induced early graft failure. In this study the effects of in vitro cell extraction on extracellular matrix molecules and in vivo remodeling of decellularized aortic valves were investigated in a heterotopic aortic valve rat implantation model. METHODS: Rat aortic valve conduits were decellularized by a 2-step detergent-enzymatic extraction method involving sodium dodecyl sulfate in combination with RNase and DNase. Cellular and acellular allogeneic (2x, n = 4) and syngeneic valve grafts (2x, n = 3) were grafted infrarenally into the descending aorta for 21 days. Immunohistochemical techniques were used to study extracellular matrix constitution (elastin, collagen, fibronectin, and chondroitin sulfate) and cellular infiltration. RESULTS: The decellularization procedure resulted in a complete loss of all cellular structures from the entire valve conduit with minimal damage to the extracellular matrix. All transplanted cellular allografts became deformed, swollen, and acellular with major changes in extracellular matrix structure. The transplanted decellularized allografts, however, retained normal preserved valve leaflets comparable to transplanted cellular and acellular syngeneic grafts. With the exception of cellular syngeneic grafts, all other grafts showed retrovalvular thrombi. CONCLUSIONS: Damage to the valves caused by decellularization technique is much less than the damage caused by the recipient's immune response. In vitro removal of viable cells in (cryopreserved) homografts may decrease graft failure. Seeding with autologous or major histocompatibility complex-matched donor endothelial cells will be necessary to diminish damage induced by an absent blood-tissue barrier.

Animals↗