Surface modification of a polyether-urethane with RGD-containing peptides for enhanced cell attachment and signalling

Abstract of article examining the chemical modification of polyurethane with RGD-containing peptides offers a means of encouraging the adhesion, spreading and proliferation of cells cultured on its surface. This study assesses the efficacy of a modification procedure using surface analysis techniques and preliminary cell culture studies

Applying elastic fibre biology in vascular tissue engineering

For the treatment of vascular disease, the major cause of death in Western society, there is an urgent need for tissue-engineered, biocompatible, small calibre artery substitutes that restore biological function. Vascular tissue engineering of such grafts involves the development of compliant synthetic or biomaterial scaffolds that incorporate vascular cells and extracellular matrix. Elastic fibres are major structural elements of arterial walls that can enhance vascular graft design and patency. In blood vessels, they endow vessels with the critical property of elastic recoil. They also influence vascular cell behaviour through direct interactions and by regulating growth factor activation. This review addresses physiological elastic fibre assembly and contributions to vessel structure and function, and how elastic fibre biology is now being exploited in small diameter vascular graft design

PCL-PU composite vascular scaffold production for vascular tissue engineering: attachment, proliferation and bioactivity of human vascular endothelial cells

A new compliant scaffold suitable for small-diameter vascular grafts has been developed that promotes strong attachment of endothelial cells. Composite scaffolds were produced by wet spinning polycaprolactone (PCL) fibres which form the luminal surface, then electrospinning porous polyurethane (PU) onto the back of the PCL fibres to form the vessel wall substitute. Human endothelial cells demonstrated strong attachment to the composite PCL-PU scaffold, and proliferated to form a monolayer with strong PECAM-1 expression and cobblestone morphology. Attached cells demonstrated abundant release of von Willebrand factor, nitric oxide and ICAM-1 under physiological stimuli, and exhibited an immune response to lipopolysaccharide. The composite scaffold may also deliver bioactive molecules. Active trypsin, used as a test molecule, had a defined 48 h pattern of release from luminal PCL fibres. These data confirm the potential of this novel composite scaffold in vascular tissue engineering

Endothelial and smooth muscle cell interactions with a novel 2-ply polymeric vascular scaffold with potential for bioactive release

Paper examining endothelial and smooth muscle cell interactions with a novel 2-ply polymeric vascular scaffold with potential for bioactive release

The role of endothelial cell attachment to elastic fibre molecules in the enhancement of monolayer formation and retention, and the inhibition of smooth muscle cell recruitment

The endothelium is an essential modulator of vascular tone and thrombogenicity and a critical barrier between the vessel wall and blood components. In tissue-engineered small-diameter vascular constructs, endothelial cell detachment in flow can lead to thrombosis and graft failure. The subendothelial extracellular matrix provides stable endothelial cell anchorage through interactions with cell surface receptors, and influences the proliferation, migration, and survival of both endothelial cells and smooth muscle cells. We have tested the hypothesis that these desired physiological characteristics can be conferred by surface coatings of natural vascular matrix components, focusing on the elastic fiber molecules, fibrillin-1, fibulin-5 and tropoelastin. On fibrillin-1 or fibulin-5-coated surfaces, endothelial cells exhibited strong integrin-mediated attachment in static conditions (82% and 76% attachment, respectively) and flow conditions (67% and 78% cell retention on fibrillin-1 or fibulin-5, respectively, at 25 dynes/cm2), confluent monolayer formation, and stable functional characteristics. Adhesion to these two molecules also strongly inhibited smooth muscle cell migration to the endothelial monolayer. In contrast, on elastin, endothelial cells attached poorly, did not spread, and had markedly impaired functional properties. Thus, fibrillin-1 and fibulin-5, but not elastin, can be exploited to enhance endothelial stability, and to inhibit SMC migration within vascular graft scaffolds. These findings have important implications for the design of vascular graft scaffolds, the clinical performance of which may be enhanced by exploiting natural cell-matrix biology to regulate cell attachment and function

Development of a bio-artificial blood vessel: surface modification of electrospun polyurethane scaffolds

Paper discussing the development of a bio-artificial blood vessel with surface modification of electrospun polyurethane scaffolds

Isolation of intact elastin fibers devoid of microfibrils.

Contains fulltext : 48622.pdf (publisher's version ) (Open Access)Purification protocols for elastin generally result in greatly damaged elastin fibers and this likely influences the biological response. We here describe a novel protocol for the isolation of elastin whereby the fibers stay intact, and introduce the term "elastin fiber" for intact elastic fibers with elastin as their sole component. As opposed to elastic fibers, elastin fibers do not contain any microfibrils or associated molecules. Elastin fibers were isolated from equine elastic ligaments according to various protocols and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, amino acid quantification, immunofluorescence assay, transmission/scanning electron microscopy, and cellular reactivity in vivo. The optimal protocol comprised several extraction steps and trypsin digestion. Elastin fibers were free of contaminants and had a smooth, regular appearance. The cellular response to purified, intact elastin fibers was different in comparison with purified, but affected, fibers and to contaminated fibers. Intact fibers consisting only of elastin may be important for both fundamental and applied research, for example, tissue engineering, which need well-defined preparations to study the cellular biological effect of individual components

Biomimetic Regeneration of Elastin Matrices Using Hyaluronan and Copper Ion Cues

Current efforts to tissue engineer elastin-rich vascular constructs and grafts are limited because of the poor elastogenesis of adult vascular smooth muscle cells (SMCs) and the unavailability of appropriate cues to upregulate and enhance cross-linking of elastin precursors (tropoelastin) into organized, mature elastin fibers. We earlier showed that hyaluronan (HA) fragments greatly enhance tropo- and matrix-elastin synthesis by SMCs, although the yield of matrix elastin is low. To improve matrix yields, here we investigate the benefits of adding copper (Cu2+) ions (0.01 M and 0.1 M), concurrent with HA (756–2000 kDa), to enhance lysyl oxidase (LOX)-mediated elastin cross-linking machinery. Although absolute elastin amounts in test groups were not different from those in controls, on a per-cell basis, 0.1 M of Cu2+ ions slowed cell proliferation (5.6 ± 2.3–fold increase over 21 days vs 22.9 ± 4.2–fold for non-additive controls), stimulated synthesis of collagen (4.1 ± 0.4–fold), tropoelastin (4.1 ± 0.05–fold) and cross-linked matrix elastin (4.2 ± 0.7–fold). LOX protein synthesis increased 2.5 times in the presence of 0.1 M of Cu2+ ions, and these trends were maintained even in the presence of HA fragments, although LOX functional activity remained unchanged in all cases. The abundance of elastin and LOX in cell layers cultured with 0.1 M of Cu2+ ions and HA fragments was qualitatively confirmed using immunoflourescence. Scanning electron microscopy images showed that SMC cultures supplemented with 0.1 M of Cu2+ ions and HA oligomers and large fragments exhibited better deposition of mature elastic fibers (∼1 μm diameter). However, 0.01 M of Cu2+ ions did not have any beneficial effect on elastin regeneration. In conclusion, the results suggest that supplying 0.1 M of Cu2+ ions to SMCs to concurrently (a) enhance per-cell yield of elastin matrix while allowing cells to remain viable and synthetic and not density-arrested in long-term culture because of their moderating effects on otherwise rapid cell proliferation and (b) provide additional benefits of enhanced elastin fiber formation and cross-linking within these tissue-engineered constructs