Screening for Thermostable Extracellular Amylases from Bacterial Isolates

Synthetic small-diameter vascular grafts are often a treatment for cardiovascular disease; yet failure due to thrombosis remains a problem. In situ endothelialization of graft surfaces can mitigate thrombosis. Poly(vinyl alcohol) hydrogel (PVA) is a hemocompatible biomaterial for grafting, however, its bioinert properties prevent endothelialization. Mixing extracellular matrix (ECM)-mimicking biomolecules into PVA networks increased endothelial cell (EC) attachment. Yet, platelet attachment was concomitantly increased, indicating an alteration of the material’s antithrombotic properties. Herein, we hypothesized that covalent attachment of ECM-mimicking biomolecules to PVA would specifically bind ECs without compromising hemocompatibility. We covalently attached a collagen-mimicking peptide, GFPGER, to surfaces of planar and tubular PVA. The surfaces of crosslinked PVA were activated with carbonyldiimidizole before immersion into GFPGER peptide solutions (0, 15, 30, 60 and 120µg/mL). To characterize the surface properties of the modified materials, we measured contact angle and performed XPS elemental analyses. EC attachment was quantified with a DNA assay and qualitatively examined using immunohistochemistry by staining for VE-cadherin, actin, and nuclei. We quantified hemocompatibility with in vitro platelet attachment and time to fibrin clot formation and ex vivo platelet attachment and fibrin formation in an established non-human primate whole blood shunt model. EC attachment to GFPGER-modified PVA was increased. In vitro and ex vivo hemocompatibility results showed a reduction in platelet attachment and fibrin formation onto GFPGER-modified PVA. Our results confirmed that covalently modifying PVA with GFPGER promotes EC attachment while maintaining hemocompatibility. This work is a significant step toward development of hemocompatible devices for treatment of cardiovascular disease.