Biomaterial surface properties, via alterations in the adsorbed protein layer, and the presence of specific functional groups can influence integrin binding specificity, thereby modulating cell adhesion and differentiation processes. The adsorption of fibronectin, a protein directly involved in osteoblast adhesion to the extracellular matrix, has been related to different physical and chemical properties of biomaterial surfaces. This study used blasting particles of different sizes and chemical compositions to evaluate the response of MG63 osteoblast-like cells on smooth and blasted titanium surfaces, with and without fibronectin coatings, by means of real-time reverse transcription-polymerase chain reaction (qRT-PCR) assays. This response included (a) expression of the α5, αv and α3integrin subunits, which can bind to fibronectin through the RGD binding site, and (b) expression of alkaline phosphatase (ALP) and osteocalcin (OC) as cell-differentiation markers. ALP activity and synthesis of OC were also tested. Cells on SiC-blasted Ti surfaces expressed higher amounts of the α5 mRNA gene than cells on Al2O 3-blasted Ti surfaces. This may be related to the fact that SiC-blasted surfaces adsorbed higher amounts of fibronectin due to their higher surface free energy and therefore provided a higher number of specific cell-binding sites. Fn-coated Ti surfaces decreased α5 mRNA gene expression, by favoring the formation of other integrins involved in adhesion over α5β1. The changes in a5 mRNA expression induced by the presence of fibronectin coatings may moreover influence the osteoblast differentiation pathway, as fibronectin coatings on Ti surfaces also decreased both ALP mRNA expression and ALP activity after 14 and 21 days of cell culture.
|Original language||English (US)|
|Number of pages||11|
|Journal||Journal of Materials Science: Materials in Medicine|
|State||Published - Mar 2011|
Bibliographical noteFunding Information:
Acknowledgments The authors would like to acknowledge the Spanish Interministerial Commission for Science and Technology (CICYT) for financial support under the MAT2003-08165 project. They would also like to thank Klockner S. L. for technical help in sample preparation and MPA, S. L. (Materias Primas Abrasivas) for providing the blasting particles and blasting machine. M. Pegueroles would like to thank the Universitat Politècnica de Catalunya (UPC) for grant funding to complete her PhD thesis.