title: The effect of RGD peptides on osseointegration of hydroxyapatite biomaterials.
abstract: Given that hydroxyapatite (HA) biomaterials are highly efficient at adsorbing proadhesive proteins, we questioned whether functionalizing HA with RGD peptides would have any benefit. In this study, we implanted uncoated or RGD-coated HA disks into rat tibiae for 30 min to allow endogenous protein adsorption, and then evaluated mesenchymal stem cell (MSC) interactions with the retrieved disks. These experiments revealed that RGD, when presented in combination with adsorbed tibial proteins (including fibronectin, vitronectin and fibrinogen), has a markedly detrimental effect on MSC adhesion and survival. Moreover, analyses of HA disks implanted for 5 days showed that RGD significantly inhibits total bone formation as well as the amount of new bone directly contacting the implant perimeter. Thus, RGD, which is widely believed to promote cell/biomaterial interactions, has a negative effect on HA implant performance. Collectively these results suggest that, for biomaterials that are highly interactive with the tissue microenvironment, the ultimate effects of RGD will depend upon how signaling from this peptide integrates with endogenous processes such as protein adsorption.
authors.affiliation: Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Hennessy
authors.forename: Will C
authors.initials: WC
authors.lastname: Clem
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Phipps
authors.forename: Amber A
authors.initials: AA
authors.lastname: Sawyer
authors.forename: Faheem M
authors.initials: FM
authors.lastname: Shaikh
authors.forename: Susan L
authors.initials: SL
authors.lastname: Bellis
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology; D015153:Blotting, Western; D018786:Bone Substitutes / Q000737:chemistry / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D017886:Durapatite / Q000737:chemistry*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects; D008954:Models, Biological; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology*; D016348:Osseointegration / Q000187:drug effects*; D051381:Rats; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid; D017886:Durapatite