Nitrogen‐Rich Plasma‐Polymerized Coatings on PET and PTFE Surfaces Improve Endothelial Cell Attachment and Resistance to Shear Flow

Abstract

Low seeding efficiency and poor cell retention under flow-induced shear stress limit the effectiveness of in vitro endothelialization strategies for small-diameter vascular grafts. Primary-amine-rich plasma-polymerized coatings (PPE:N) deposited using low- and atmospheric-pressure plasma discharges on PET and PTFE are evaluated for their ability to improve endothelial cells' kinetics and strength of attachment. PPE:N coatings increase cell adhesion and adhesion rate, spreading, focal adhesion, and resistance to flow-induced shear compared with bare and gelatin-coated PET and PTFE. In particular, about 90% of the cells remain on coated surfaces after 1 h exposure to shear. These coatings, therefore, appear as a promising versatile approach to improve cell seeding strategies for vascular grafts.

Electrospun Nanofiber Scaffolds and Plasma Polymerization: A Promising Combination Towards Complete, Stable Endothelial Lining for Vascular Grafts

“…In other words, plasma‐coating of the electrospun mat resulted in a much greater population density of adhering cells. This was presumably due the much enhanced surface activity of L‐PPE:N resulting from its primary amine groups, also evidenced by previously published research from these and other laboratories …”

“…However, literature data suggest that achieving good coverage of ECs on such PET scaffolds may be problematic . The reason is the polymer's surface inertness: EC adhesion, growth and resistance to flow‐induced shear stress has proven to be limited on PET . This might be overcome by a suitable treatment to increase surface roughness, surface energy, or by grafting bioactive molecules.…”

“…Numerous articles have also demonstrated the particular effectiveness of nitrogen‐, particularly of amine‐containing PP coatings . For example, N‐rich plasma‐polymerized ethylene (L‐PPE:N) coatings deposited on PET and PTFE films showed that EC adhesion rate, spreading, focal adhesion, and resistance to flow‐induced shear were greatly improved, compared with bare and gelatin‐coated PET and PTFE . In other words, L‐PPE:N appears to be a particularly promising candidate for the endothelialization of vascular grafts …”

Derivatization of Plasma Polymerized Thin Films and Attachment of Biomolecules to Influence HUVEC‐Cell Adhesion

“…Within 24 h HUVECS were seen to adhere and after 3 d they were beginning to show areas of confluence on the pp‐AA coated PTFE surfaces. Improved cell adhesion on plasma polymerized amine‐rich films have previously been reported for HUVECS,33 for P19 carcinoma cells and neurons,14 osteoblasts,34, 35 and human mesenchymal stem cells,36, 37 to name but a few. The chemical modification of the pp‐AA with the diepoxide significantly reduced the adhesion characteristics at the biotic–abiotic interface.…”

Characterization and comparison of N‐, O‐, and N+O‐functionalized polymer surfaces for efficient (HUVEC) endothelial cell colonization

“…Indeed, primary amine groups (NH 2 ) are particularly well known to enhance cell adhesion, likely due to their positive charge at physiological pH that allows them to attract negatively‐charged biomolecules like adhesive glycoproteins (fibronectin, vitronectin), which adsorb on the surface and in turn enhance cell binding via integrin receptors at the cell surface. Thus, a low‐pressure plasma‐polymerized primary amine‐rich coating, “L‐PPE:N,” developed in our laboratory, has proven very efficient in promoting the adhesion and proliferation of U937 monocytes, of vascular smooth muscle cells (VSMCs) and of endothelial cells (EC), as well as for improving resistance of the latter to shear stress. Amine functional groups also widely serve to covalently graft other biologically active molecules …”