Investigation of platelet adhesion, platelet activation, and platelet morphology was performed on Hexafluoroethane coated glass coverslips, Fluorinated Ethylene Propylene (FEP), and Polymethyl Methacrylate (PMMA) thin film polymers. Hexafluoroethane was coated on glass coverslips using Radio Frequency Glow Discharge (RFGD) polymer deposition and was supplied by researchers at the University of Washington in Seattle. For several years now, analogously prepared Fluoropolymer surfaces have been reported to exhibit unique protein adsorption properties and reduced adherent platelet concentrations compared to standard fluoropolymers and non-fluorinated polymers (Kiaei, 1995). Platelet interactions were assessed using a novel, dynamic, and physiologically relevant experimental system. In-vitro tests were performed on polymer surfaces mounted in a light transparent flow cell by pumping whole blood through the apparatus to deposit platelets over the polymer surface. Red blood cells were rinsed from the flow cell with plasma immediately after platelet deposition to permit observation of adherent cells. Dynamic, real time single cell morphology observation was made under low flowing plasma conditions using light microscopy and recorded using a computer image acquisition system. Physiologic conditions were maintained using a low plasma flow rate which ensured available nutrients for platelets as tests were performed for up to 90 minutes. Compared to PMMA and FEP, Hexafluoroethane surfaces exhibited the lowest platelet surface concentrations with overall mean adherent platelet concentrations of 8165, 6895, and 4387 platelets per mm², respectively. PMMA is a more activating surface compared to the fluoropolymers tested, however, the rate of progress of platelet activation and morphological trends are similar between the Hexafluoroethane and FEP polymer surfaces. Activation parameters, a quantification of the state of platelet activation, support experimental observations made concerning morphological change information on Hexafluoroetbane, FEP, and PMMA. A Scanning Electron Microscopy study involving all three test surfaces, fixed after 60 or 90 minute plasma flow maintained experiments, support the hypothesis that the pancake platelet evolves from a spreading platelet. Routinely observed, pancake platelets are circular, 3-5 μm in diameter, and have round raised protuberances at the periphery of the cell membrane. Images showing several stages of spread cell retraction on Fluoropolymers tested without added thrombin stimulant give greater detail of peripheral fragmentation and further support a mechanism for polymer surface induced platelet microparticle formation. / Thesis / Master of Engineering (ME)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22927 |
| Date | 08 1900 |
| Creators | Anderson, James |
| Contributors | Feuerstein, I. A., Chemical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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