Characterization of transient platelet contacts on a polyvinyl alcohol hydrogel by video microscopy.
Acridine orange labelled, washed human platelets were counted and tracked on polyvinyl alcohol (PVA), heparin-PVA and polyethylene (PE)-coated coverslips with a view to understand why transient contact on the PVA hydrogels lead to elevated platelet activation and consumption relative to polyethylene. Over the 4 min of initial contact that was studied, platelet adhesion was higher on PE than on PVA or heparin-PVA at both 40 and 200 s(-1), as expected, regardless of whether the surfaces were pre-treated with albumin or fibrinogen. Not all platelets appearing to make contact with the surface, actually attached. For example, less than 2% of the platelets contacting albumin pre-treated PVA (at 40 s(-1)) remained adherent at the end of the initial 60 s observation time, while the corresponding number for PE was greater than 9%. A greater fraction of the platelets remained adherent at the higher shear rate or with fibrinogen pre-treatment, but the difference between PVA and PE remained similar: for example, with fibrinogen pre-treatment at 200 s(-1), approximately 25% of the platelet contacts resulted in adhesion on PVA while 66% did so on PE. While net platelet adhesion was less for the hydrogels, than for PE, the total number of contacts (adherents + non-adherents) were more comparable and unexpectedly higher for albumin pre-treatment than for fibrinogen. Net platelet adhesion is but one component of the total platelet interaction with a material surface. Fluorescent video microscopy has been shown to be a useful, albeit not unequivocal, method for assessing the platelets that make contact with but do not adhere to a surface. reserved
Godo
M N
MN
Department of Chemical Engineering and Applied Chemistry and Centre for Biomaterials, University of Toronto, Ont., Canada.
Sefton
M V
MV
D001672:Biocompatible Materials; D001792:Blood Platelets / Q000502:physiology*; D005340:Fibrinogen / Q000502:physiology; D006493:Heparin; D006801:Humans; D020100:Hydrogels; D066298:In Vitro Techniques; D018715:Microscopy, Video; D010973:Platelet Adhesiveness / Q000502:physiology*; D011095:Polyethylenes; D011142:Polyvinyl Alcohol; D012710:Serum Albumin, Bovine / Q000502:physiology
D001672:Biocompatible Materials; D020100:Hydrogels; D011095:Polyethylenes; C058382:heparin-polyvinyl alcohol hydrogel; C062364:polyvinyl alcohol hydrogel; D012710:Serum Albumin, Bovine; D005340:Fibrinogen; D011142:Polyvinyl Alcohol; D006493:Heparin