title: Mechanisms underlying the attachment and spreading of human osteoblasts: from transient interactions to focal adhesions on vitronectin-grafted bioactive surfaces.
abstract: The features of implant devices and the reactions of bone-derived cells to foreign surfaces determine implant success during osseointegration. In an attempt to better understand the mechanisms underlying osteoblasts attachment and spreading, in this study adhesive peptides containing the fibronectin sequence motif for integrin binding (Arg-Gly-Asp, RGD) or mapping the human vitronectin protein (HVP) were grafted on glass and titanium surfaces with or without chemically induced controlled immobilization. As shown by total internal reflection fluorescence microscopy, human osteoblasts develop adhesion patches only on specifically immobilized peptides. Indeed, cells quickly develop focal adhesions on RGD-grafted surfaces, while HVP peptide promotes filopodia, structures involved in cellular spreading. As indicated by immunocytochemistry and quantitative polymerase chain reaction, focal adhesions kinase activation is delayed on HVP peptides with respect to RGD while an osteogenic phenotypic response appears within 24h on osteoblasts cultured on both peptides. Cellular pathways underlying osteoblasts attachment are, however, different. As demonstrated by adhesion blocking assays, integrins are mainly involved in osteoblast adhesion to RGD peptide, while HVP selects osteoblasts for attachment through proteoglycan-mediated interactions. Thus an interfacial layer of an endosseous device grafted with specifically immobilized HVP peptide not only selects the attachment and supports differentiation of osteoblasts but also promotes cellular migration.
authors.affiliation: Department of Molecular Medicine, University of Padova, 35121 Padova, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Brun
authors.forename: Michele
authors.initials: M
authors.lastname: Scorzeto
authors.forename: Stefano
authors.initials: S
authors.lastname: Vassanelli
authors.forename: Ignazio
authors.initials: I
authors.lastname: Castagliuolo
authors.forename: Giorgio
authors.initials: G
authors.lastname: Palù
authors.forename: Francesca
authors.initials: F
authors.lastname: Ghezzo
authors.forename: Grazia M L
authors.initials: GM
authors.lastname: Messina
authors.forename: Giovanna
authors.initials: G
authors.lastname: Iucci
authors.forename: Valentina
authors.initials: V
authors.lastname: Battaglia
authors.forename: Stefano
authors.initials: S
authors.lastname: Sivolella
authors.forename: Andrea
authors.initials: A
authors.lastname: Bagno
authors.forename: Giovanni
authors.initials: G
authors.lastname: Polzonetti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Marletta
authors.forename: Monica
authors.initials: M
authors.lastname: Dettin
mesh_terms: D000327:Adsorption; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000378:metabolism*; D022001:Focal Adhesions / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D019096:Vitronectin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D020099:Coated Materials, Biocompatible; D009842:Oligopeptides; D019096:Vitronectin; C047981:arginyl-glycyl-aspartic acid