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OBJECTIVE: Different materials have been used for heart valves and vascular prostheses. Major drawbacks of current implanted valves are either the need for strong anticoagulants or moderate durability and low resistance to fatigue and tear. Ultra High Molecular Weight Polyethylene (UHMWPE) fibers are flexible, fatigue- and tear resistant and have high strength. Therefore, prostheses made of medical-grade UHMWPE fibers might be attractive for construction of heart valves applied in transcatheter approaches. The aim of this study is to test the biocompatibility of medical-grade UHMWPE fibers in vitro in blood contact.
METHODS: Blood of three randomly chosen donors was subjected to three different experiments. First, platelet adhesion on filaments (Ø 15μm) of medical-grade UHMWPE fibers and Polyester (gold standard) were tested in Polydimethylsiloxane (PDMS) perfusion chambers and visualized by light microscopy. Secondly, woven patches of medical-grade UHMWPE fibers were compared with the 5 most commonly used commercially available vascular patch prostheses, i.e. a knitted and a woven polyester fabric and 3 different ePTFE patches. Commercially available patches were tested as they are, meaning that they may contain a coating and that the construction and surface characteristics of these patches are different from the patch of UHMWPE fibers. Coagulation activation was tested by measuring the thrombin formation caused by the patches over time. Thirdly, platelet adhesion, activation and aggregation on the patches were studied in a flow chamber and thereafter visualized by the use of scanning electron microscopy.
RESULTS: The platelet adhesion on medical-grade UHMWPE filaments was significantly lower compared with polyester filaments in the PDMS perfusion chamber experiment (P=0.03). The time to peak and total formed thrombin in the coagulation experiment was non-inferior for patches of UHMWPE fibers, compared to the reference materials. Currently, the scanning electron microscopic results of the patch perfusion tests are being analyzed.
CONCLUSIONS: These experiments support the idea that medical-grade UHMWPE fibers hold promise to be a potentially suitable material in blood for prosthetic valves and other vascular purposes. Yet, more extensive (in vivo) haemocompatibility studies are needed to confirm if UHMWPE is a suitable candidate for use in prosthetic heart valves and other vascular applications.