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Gonzalez, Jessie Kevin

University of British Columbia

Blood-contacting biomaterials are commonly and increasingly used in medical devices including for example, vascular grafts, coronary stents, prosthetic heart valves, and extracorporeal pumps. A major and persistent problem of exposing blood to a foreign biomaterial surface is that a thromboinflammatory response is triggered that may cause device failure and/or systemic inflammation and clotting. Several biomaterial coatings, particularly heparin, are currently used to prevent thromboinflammation, but these do not reliably work. The goal of my thesis was to develop a novel blood compatible surface coating that simultaneously prevents thrombosis and inflammation by immobilizing anticoagulant and anti-inflammatory molecules in a more functional manner, onto a universal surface coating. This thesis is divided into two parts. In the first part, I chemically modified unfractionated heparin, a potent anticoagulant, on one end such that it could be conjugated to the universal antifouling surface coating in an orientation that optimally and uniformly exposed its anticoagulant antithrombin binding site. The functional properties of this heparin coating were tested under static and dynamic conditions, and these verified that this novel heparin coating was protective against thrombosis. In the second part, I modified the cDNA encoding the naturally occurring anti-inflammatory lectin-like domain of thrombomodulin (TM-LLD), such that it could be expressed by cultured mammalian cells, purified by affinity chromatography, and then conjugated to the antifouling surface coating in an accessible orientation. The purified soluble TM-LLD exhibited anti-inflammatory properties, in that it dampened leukocyte adhesion and complement activation. However, its activity when bound to the surface coating has yet to be confirmed. While further studies are required to optimize the function and to test the stability of these immobilized molecules, this thesis has provided proof-of-concept that the potent anti-coagulant, heparin, and the anti-inflammatory TM-LLD, can be chemically modified for conjugation to the antifouling surface in an orientation to optimize function. Future work will include experiments to upscale production of the modified proteins, to verify their functions and stability under different conditions, and finally, to apply combinatorial approaches to simultaneously bind the molecules to the coating to yield a truly biocompatible, biomaterial surface that prevents both thrombosis and inflammation.

Text

2023-12-01

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/86722

Pathology and Laboratory Medicine

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/