title: The differential regulation of osteoblast and osteoclast activity by surface topography of hydroxyapatite coatings.
abstract: The behavior of bone cells is influenced by the surface chemistry and topography of implants and scaffolds. Our purpose was to investigate how the topography of biomimetic hydroxyapatite (HA) coatings influences the attachment and differentiation of osteoblasts, and the resorptive activity of osteoclasts. Using strategies reported previously, we directly controlled the surface topography of HA coatings on polycaprolactone discs. Osteoblasts and osteoclasts were incubated on HA coatings having distinct isotropic topographies with submicrometer and micro-scale features. Osteoblast attachment and differentiation were greater on more complex, micro-rough HA surfaces (Ra ~2 μm) than on smoother topographies (Ra ~1 μm). In contrast, activity of the osteoclast marker tartrate-resistant acid phosphatase was greater on smoother than on micro-rough surfaces. Furthermore, scanning electron microscopy revealed the presence of resorption lacunae exclusively on smoother HA coatings. Inhibition of resorption on micro-rough surfaces was associated with disruption of filamentous actin sealing zones. In conclusion, HA coatings can be prepared with distinct topographies, which differentially regulate responses of osteoblasts, as well as osteoclastic activity and hence susceptibility to resorption. Thus, it may be possible to design HA coatings that induce optimal rates of bone formation and degradation specifically tailored for different applications in orthopedics and dentistry.
authors.affiliation: Department of Chemical and Biochemical Engineering, Faculty of Engineering, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Costa
authors.forename: Paul D H
authors.initials: PD
authors.lastname: Prowse
authors.forename: Tom
authors.initials: T
authors.lastname: Chrones
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Sims
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Hamilton
authors.forename: Amin S
authors.initials: AS
authors.lastname: Rizkalla
authors.forename: S Jeffrey
authors.initials: SJ
authors.lastname: Dixon
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D040761:Biomimetic Materials / Q000494:pharmacology; D001862:Bone Resorption / Q000473:pathology; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D017886:Durapatite / Q000494:pharmacology*; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D013499:Surface Properties; D000071681:Tartrate-Resistant Acid Phosphatase
chemical_list: D000199:Actins; D015415:Biomarkers; D020099:Coated Materials, Biocompatible; D007527:Isoenzymes; D017886:Durapatite; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase
keywords: Biomimetic material; Hydroxyapatite coating; Osteoblast; Osteoclast; Surface roughness; Surface topography