title: Platelet interactions with calcium-phosphate-coated surfaces.
abstract: Many studies have shown that calcium-phosphate (CaP)-coated endosseous implants exhibit more peri-implant bone formation and bone contact at early healing times than uncoated implants. Since the rate of healing is influenced by blood/implant interactions and possibly the degree of blood platelet activation, the aim of this study was to determine whether the topography, microtopography, or the presence of calcium (Ca) and phosphate (PO(4)) ions in the implant surface plays a predominant role in platelet activation. We define the threshold between topography and microtopography as the limit of the scale range of platelets themselves; thus, a microtopographic surface is defined by one which exhibits features 3mum. With the help of four international collaborating laboratories, we prepared 11 titanium and CaP-modified titanium surfaces each with different (micro)topographies and interrogated these surfaces with both platelet adhesion (lactate dehydrogenase activity) and platelet activation (microparticle formation and P-selectin expression) assays. Our results show that: calcium (Ca)- and phosphate (PO(4))-containing surfaces of increasing surface microtopographical complexity exhibit increasing platelet activation; surfaces with similar surface microtopographies show similar levels of platelet activation regardless of the presence of Ca and PO(4) in the surface; and that surface microtopography is responsible for platelet activation rather than the presence of Ca and PO(4) in the surface.
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Ont., Canada.
authors.forename: Lena
authors.initials: L
authors.lastname: Kikuchi
authors.forename: Jun Y
authors.initials: JY
authors.lastname: Park
authors.forename: Charles
authors.initials: C
authors.lastname: Victor
authors.forename: John E
authors.initials: JE
authors.lastname: Davies
mesh_terms: D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D002130:Calcium Phosphates / Q000032:analysis / Q000737:chemistry* / Q000494:pharmacology*; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000032:analysis / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D008422:Materials Testing; D008968:Molecular Conformation; D015539:Platelet Activation / Q000187:drug effects / Q000502:physiology*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; C020243:calcium phosphate; D014025:Titanium