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Biomedical subjects

B R McAuslan

Publications and source records attributed to B R McAuslan.

At least 19 recordsLinked to original sources
PubMed1988

Cell growth on metallic glasses: the interaction of amorphous metal alloys with cultured neuronal, osteoblast, endothelial, and fibroblast cells.

Ferrous based, corrosion resistant amorphous alloys supported the adhesion and growth of cultured chick neuronal cells, human marrow stromal cells (presumptive osteoblasts), bovine aortal endothelial cells, and hamster kidney fibroblasts. Alloys of compositions Fe60Ni10Cr10P13C7, Fe70Cr10P13C7, and Fe70Cr10P13B7 were found to be suitable. In contrast the crystalline form of these alloys was markedly less effective. Outgrowth of neurites from neuronal cells was promoted by precoating the metal surface with either laminin or neurite promotion factor. The adhesion of osteoblasts and fibroblasts suggests that corrosion resistant metal glasses should be considered as biomaterials useful for orthopedic applications. The adhesion of neuronal cells accompanied by neurite outgrowth indicates that the system might provide a functional interface between the neuromuscular system and an electromagnetic material that could be useful in bionic engineering.

Alloys↗
PubMed1988

Cell responses to biomaterials. II: Endothelial cell adhesion and growth on perfluorosulfonic acid.

We report here the use of perfluorosulfonic acid (Nafion) as a substratum for the growth of bovine aortal endothelial cells. This support which can be generated in a number of forms is at least as efficient in maintaining the growth of endothelial and other cell types as tissue culture grade polystyrene (TCP) and represents an advance in this regard over polytetrafluoroethylene (Teflon). The mechanism underlying the different cell attachment capacities of these three polymers is not readily related to their different protein binding patterns. While Nafion adsorbs more total protein from serum than Teflon or TCP, it adsorbs relatively less of the major cell adhesive proteins, vitronectin and fibronectin, than does Teflon. Both Nafion and Teflon had comparable but low thrombogenic potential by in vitro tests. Teflon or expanded Teflon (Gore-tex) coated with a thin film of Nafion assumes the cell supportive characteristics of Nafion and hence the modification of these surfaces by the induction of a stable bond between Teflon (in various forms) and Nafion may provide a composite vascular graft material which has all the desirable qualities of both materials.

Animals↗
PubMed1988

Matrix control of tumor angiogenesis.

Endothelial cell migration is a key feature of angiogenesis. Epidermal Growth Factor (EGF) or Tumor Angiogenesis Factor (TAF) induce cell migration and angiogenesis. When the matrix components, collagen or fibronectin, were used as a substratum in the phagokinesis assays, EGF- or TAF-induced cell migration was inhibited. It has been proposed that TAF activates cellular protease causing the matrix degradation that is evident during neovascularization in vitro. If such degradation leads to cell migration and angiogenesis, then other agents that interfere with the synthesis or assembly of matrix components should stimulate cell migration and angiogenesis. The proline analogues cis hydroxyproline, azetidine and dehydroproline are known modulators of cellular collagen synthesis. At optimal concentration (10(-5)M) these analogues caused 3-fold increases in endothelial cell migration rates in vivo as tested by a subcutaneous implant assay. We conclude from these studies that: (i) matrix components control cellular migration rates; high concentration of collagen or fibronectin inhibit angiogenically active inducers of endothelial cell migration. (ii) Intracellular modulation of synthesis of collagens leads to angiogenesis by stimulating cell migration. These findings relate to tumor angiogenesis and that TAF might trigger angiogenesis either by activation of latent proteases or by some modification of matrix assembly during synthesis that affects cell adhesion and migration.

Animals↗
PubMed1988

Mechanisms of serum protein binding and cell anchorage to immobilized serotonin and indole analogs.

Bovine aortal endothelial cells, bovine smooth muscle cells, chick embryo fibroblasts, and baby hamster kidney cells all attached and grew on immobilized tryptamine or L-tryptophan as successfully as on immobilized serotonin. A detailed investigation employing different serum compositions combined with cell blotting and immunoblotting techniques revealed that adhesion of cells to each of the immobilized indole analogs was mediated by vitronectin and fibronectin. Quantitative analyses revealed major differences in the variety of serum proteins adsorbed to each of the immobilized indole analogs and in particular major differences in the amounts of adsorbed vitronectin. However, similar levels of adsorbed fibronectin and fibronectin fragments were found on each of the immobilized indole analogs. The results indicate that (i) different composites of surface-adsorbed proteins may be directed by chemical differences between the immobilized indole analogs and (ii) mammalian cells may still populate chemically different surfaces with equal success despite differences in the surface profiles of adsorbed serum proteins.

Animals↗
PubMed1988

Induction of endothelial cell migration by proline analogs and its relevance to angiogenesis.

The proline analogs cis-4-hydroxy-L-proline, 3,4-dehydro-L-proline, and 2-azetidinecarboxylic acid induced increases in the migration rate of retinal capillary endothelial cells, aortal endothelial cells, corneal endothelial cells, aortal smooth muscle cells, and retinal pericytes. cis-4-hydroxy-D-proline did not. The optimal concentration for migration induction by any of the active agents was approximately 10(-5) M. At higher concentrations (5 x 10(-4) M) migration was not induced or was inhibited. When tested by subcutaneous implant assays in rabbits, cis-4-hydroxy-L-proline and 2-azetidinecarboxylic acid consistently elicited a marked angiogenic response. Whereas these compounds are known to modulate collagen synthesis and secretion, the concentrations at which they are effective inducers of migration suggest that they may have a more specific target than general collagen synthesis.

Animals↗
PubMed1987

Cell responses to biomaterials. I: Adhesion and growth of vascular endothelial cells on poly(hydroxyethyl methacrylate) following surface modification by hydrolytic etching.

Hydrogels of poly(hydroxyethyl methacrylate) (polyHEMA) homopolymer do not normally support the attachment and growth of mammalian cells. By altering the surface it has been possible to dramatically change this cell-substratum interaction so that vascular endothelial cells can attach and completely populate a polyHEMA surface. While this can be achieved by copolymerisation of polyHEMA with methacrylic acid or diethylaminoethyl methacrylate, it is most conveniently achieved by brief treatment of polyHEMA hydrogel with concentrated sulphuric acid. The resultant creation of surface-COOH groups, revealed by electron spectroscopy for chemical analysis, is consistent with the hydrolytic formation of methacrylic acid on the surface layer. Surface--COOH groups created by treatment with chloric or hydrofluoric acids were not effective. Following sulfuric acid treatment, cell adhesion and growth on polyHEMA hydrogel were better than on Teflon and approached those attained on glow-discharge-treated polystyrene. The capacity of acid-treated polyHEMA to adsorb albumin or fibronectin was of the order of 100-fold or 10-fold lower respectively than either polystyrene, Teflon, or segmented polyurethane. Hydrolytic "etching" in this way is proposed as an efficient means of expanding the use of polyHEMA hydrogel as a biomaterial without modifying the overall physicochemical properties of the bulk of the material.

Acrylates↗
PubMed1987

Immobilized serotonin: a novel substrate for cell culture.

Baby hamster kidney cells, bovine aortal endothelial cells, bovine smooth muscle cells, and chick embryo fibroblasts were all observed to attach and grow on serotonin which had been immobilized by covalent coupling to agarose beads. While growth and morphology of cells on immobilized serotonin appeared normal, a change in cell function may have occurred since the pattern of polypeptides expressed by these cells was different from that of cells grown on two other substrates: immobilized fibronectin and tissue culture plastic. By changing the composition of the fetal calf serum proteins in the growth medium it was shown that cells attach directly to immobilized fibronectin without mediation by medium components. In contrast, cells were found not to attach directly to immobilized serotonin but to attach indirectly via factors absorbed onto immobilized serotonin from fetal calf serum. The major component of this cell attachment activity was shown not to be fibronectin and was identified following separation by SDS-PAGE, electroblotting, and cell binding on nitrocellulose filters. The cell attachment activity compromises a major protein species of Mr 70,000 which is the molecular size of the recently identified serum spreading factor also called vitronectin.

Adsorption↗
PubMed1986

Selenium-induced cell migration and proliferation: relevance to angiogenesis and microangiopathy.

Selenium, as selenomethionine, selenocystine, or selenious acid, activated both capillary and aortal endothelial cells of bovine origin. To low concentrations of selenium (10(-7) M) retinal capillary cells (BRCE) responded by a fivefold increase in migration rate whereas the migration rate of aortal cells was not markedly altered. In contrast, the proliferation rate of aortal cells was increased up to 300% or more by selenium addition whereas the proliferation rate of capillary derived cells was almost unaffected. Selenomethionine was strongly angiogenic by the corneal pocket or chorioallantoic membrane assays. These findings bear on the establishment of criteria for defining angiogenic factors and may also relate to selenium deficiency-linked vascular disease.

Animals↗
PubMed1985

New functions of epidermal growth factor: stimulation of capillary endothelial cell migration and matrix dependent proliferation.

The proliferative response of bovine retinal capillary endothelial cells to EGF is dependent upon attaching the cells to a matrix of fibronectin. Bovine capillary endothelial cells are also stimulated to actively migrate when exposed to EGF in vitro. These activities provide an explanation for the angiogenic properties of EGF in vivo. Capillary cell migration and proliferation are proposed as sensitive quantifiable bioassays to explore the functional domains of the EGF molecule. Studies on the inactivation of these properties of EGF by specific cleavage of the molecule with CNBr or proteases suggest that an intact loop composed in part by amino acid residues 20 to 31 is essential for at least some functions.

Animals↗
PubMed1984

Similarity of the carbohydrate moieties of fibronectins derived from blood plasma and synthesised by cultured endothelial cells.

Plasma and cellular fibronectins are reported to be very similar but not identical in chemical structure. We have compared bovine plasma fibronectin with fibronectin secreted by bovine aortal endothelial cells in culture. Techniques were chosen to highlight likely structural differences, particularly in the carbohydrate moieties. Both fibronectins were wholly reactive to monospecific antiserum and behaved identically in two-dimensional gel electrophoresis. The oligosaccharide chains were identical in proportion and degree of sialylation by anion-exchange HPLC. Fractionation of the glycopeptides on immobilised lectins and serotonin showed that both fibronectins contained (i) predominantly biantennary oligosaccharides, (ii) exclusively N-acetylneuraminic acid residues in a non-clustered array and (iii) no L-fucose residues. The overriding structural similarities support the proposal that the endothelium is a site of synthesis of plasma fibronectin in vivo.

Animals↗
PubMed1983

Angiogenic factors and their assay: activity of formyl methionyl leucyl phenylalanine, adenosine diphosphate, heparin, copper, and bovine endothelium stimulating factor.

A number of chemically unrelated substances have been compared for their neovasculogenic activity by two different in vivo tests, and for their ability to induce cultured endothelial cell migration and proliferation. Formyl methionyl leucyl phenylalanine, copper ions, heparin, adenosine diphosphate, and low-molecular-weight bovine endothelium stimulating factor were all neovasculogenic by the corneal pocket assay. By the chorioallantoic membrane assay, copper ions and formyl methionyl leucyl phenylalanine were not detectably neovasculogenic. By the same assay it has been possible to demonstrate angiogenic activity in bovine endothelium stimulating factor that is distinguishable from copper ions. This bovine factor, in contrast to the other agents, induced marked endothelial cell migration and also proliferation and may belong to a special class of agents which represents direct acting angiogenic activity.

Adenosine Diphosphate↗
PubMed1983

Rapid purification of collagen binding glycoproteins secreted by cultured endothelial cells.

Two distinct lines of bovine aortal endothelial cells and also chick embryo fibroblasts, secrete two major non-associating collagen binding proteins into the growth medium. Both proteins are anionic, mannose-containing glycoproteins but differ in molecular weight (Mr = 220,000 and 70,000 daltons respectively), affinity for heparin and reactivity to antiserum against plasma fibronectin. The large molecular weight glycoprotein was identified as fibronectin. In this paper we present a novel rapid procedure for purification of each glycoprotein under non-denaturing conditions. A simple two step affinity column procedure was used to achieve high yields (80% and 85% respectively) of native, non-denatured glycoproteins suitable for fine analytical purposes and cell interaction studies.

Animals↗
PubMed1982

Modulation of synthesis of specific proteins in endothelial cells by copper, cadmium, and disulfiram: an early response to an angiogenic inducer of cell migration.

Copper, cadmium, and disulfiram (an ionophore for copper) modulate the synthesis of several polypeptides in two clonal lines of bovine aortal endothelial cells. After treatment of Type 1 endothelial cells with 10(-3) M CuSO4 or 10(-5) M CdCl2 four cell-associated polypeptides (Mr = 28,000, 32,000, 73,000, and 83,000 daltons) were induced. In contrast, in Type 2 endothelial cells, which have cultural characteristics distinct from Type 1, only one new cell-associated protein (Mr = 32,000 daltons) was induced by CuSO4 or CdCl2. The same four polypeptides, described above, were induced by disulfiram (10(-7) M) in Type 1 endothelial cells. In contrast when Type 2 endothelial cells were treated with disulfiram the synthesis of only two new cell-associated proteins (Mr = 32,000 and 40,000 daltons) was induced. Other differences are revealed by analyses of proteins secreted into the growth medium. In particular low levels of only CuSO4 (10(-6) M) enhanced the synthesis in Type 2 cells of a protein (Mr = 220,000 daltons) identified as fibronectin. Since only copper ions induced fibronectin, we propose that the mechanism of induction of fibronectin synthesis, in contrast to the induction of cell-associated polypeptides, does not involve a sulphydryl-containing receptor molecule. It is suggested that the specific enhancement of fibronectin synthesis by copper ions may be a controlling event in the stimulation by copper ions of endothelial cell migration and angiogenesis.

Animals↗
PubMed1982

Signals causing change in morphological phenotype, growth mode, and gene expression of vascular endothelial cells.

Comparison of three different lines of bovine aortal endothelial cells provides a clear demonstration of reversible morphologic phenotype coincidental with change in expression and growth mode. These phenotypic forms can be externally controlled so that cells may exist either in an epithelioid contact-inhibitable state or as a fibroblastoid non-contact-inhibitable state. Clonal cell line N (normal) shows a strong tendency to maintain the epithelioid phenotype. Clonal cell line Sp (sprout) can readily and reversibly adopt the epithelioid or fibroblastoid phenotype. A factor in normal serum is responsible for maintaining the cells in the epithelioid phenotype. This factor could be a growth factor since several polypeptide growth factors are shown to drive cells from the fibroblastoid phenotype to the epithelioid phenotype within 11 hours. This growth factor-induced change is not mediated through induced DNA synthesis. Clonal cell line V (variant) normally maintains the fibroblastoid phenotype but can be directed to the epithelioid phenotype provided cells are on an appropriate collagenous matrix. Associated with these changes in morphological phenotype are depression of the expression of the pro alpha 2 chain of collagen type I which may be characteristic of the contact-inhibited state and of an 80,000 mol wt polypeptide synthesized only by cells in the fibroblastoid phenotype. An endothelial cell collagen EC1 (mol wt 177,000) was synthesized by all cell lines regardless of phenotype whereas a suspected breakdown product EC3 (mol wt 100,000) was found only in the epithelioid phenotype. Other differences and similarities between cell lines include expression of a 135,000 mol wt glycoprotein GP (V and N), the procollagen of collagen type III (N) of fibronectin (N, V, Sp), and of the pro alpha 1 chain of collagen type I (Sp, V). The characteristic expression of each line and its response to signals controlling morphologic phenotype impinges on the question of whether there exist several distinct types of vascular endothelial cells with different functional potentials controlled by extracellular signals.

Animals↗
PubMed1980

Variant endothelial cells. Fibronectin as a transducer of signals for migration and neovascularisation.

A morphologic and growth control variant of bovine aortal endothelial cells has been isolated and shown to synthesise factor VIII antigen (McAuslan and Reilly '79). The variant also possesses the endothelial surface markers angiotensin converting enzyme and alpha 2-microglobulin. The normal cell synthesises fibronectin and deposits it underneath the cells; the variant also synthesises fibronectin. At least three times more fibronectin is distributed over the upper cell surface of variants. This correlates with the three-fold increased binding of the replication inhibitor Con A and suggests a role of fibronectin in endothelial cell growth control. When stimulated to migrate by CuII ions, the variant leaves deposits of fibronectin in its trail; in contrast, migrating normal cells do not, but they do redistribute their surface fibronectin. As revealed by scanning electron microscopy, variant cells are unusual in that they grow over or under cultured normal endothelial cells. It is proposed that during the process of neovascularisation, variant cells have a special function as lead cells that lay down fibronectin on which an endothelium can become established.

Animals↗