title: Surface-induced changes in protein adsorption and implications for cellular phenotypic responses to surface interaction.
abstract: Understanding external factors that determine cellular phenotypic responses is of key interest in the field of biomaterials. Currently, material surface characteristics, protein adsorption and cellular phenotypic responses are all considered to be interrelated and ultimately determine the biocompatibility of materials. The exact nature of the relationship between these distinct, yet related, phenomena still remains to be elucidated. Through the use of a series of thermoresponsive N-isopropylacrylamide-based co-polymer films, we aimed to shed light on the relationship between surface hydrophobicity, protein adsorption and subsequent cellular response. Despite changes in co-polymer hydrophobicity mediated by altered ratios of constituent monomers, differential cellular response was only apparent in the presence of serum. Co-polymer films displayed alterations with respect to the amount of protein adsorbed on the surface, with individual serum proteins (albumin and fibronectin) displaying contrasting adsorption characteristics. Changes in protein adsorption corresponded to changes in cell adhesion, cytoskeletal organisation and cell morphology, as well as to changes in cell movement and intracellular signalling events. Examination of focal adhesion kinase (FAK), and extracellular signal-regulated kinase (ERK 1/2), important mediators of adhesion and growth factor-related signalling events, revealed a comparative reduction in phosphorylation of these signalling proteins in cells grown on co-polymers in comparison to those cultured on tissue culture polystyrene (TCP; used as a control surface). We also associated surface-mediated phenotypic alterations of cells grown on TCP and co-polymer films with particular changes in gene expression. These results indicate that cellular response to interaction with our series of co-polymer films is determined by the surface-adsorbed protein layer, which in turn is determined by the changing surface chemistry as the ratio of the co-monomers is altered.
authors.affiliation: UCD School of Biomolecular and Biomedical Science, Centre for Molecular Medicine, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Lorcan T
authors.initials: LT
authors.lastname: Allen
authors.forename: Miriam
authors.initials: M
authors.lastname: Tosetto
authors.forename: Ian S
authors.initials: IS
authors.lastname: Miller
authors.forename: Darran P
authors.initials: DP
authors.lastname: O'Connor
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Penney
authors.forename: Iseult
authors.initials: I
authors.lastname: Lynch
authors.forename: Alan K
authors.initials: AK
authors.lastname: Keenan
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Pennington
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Dawson
authors.forename: William M
authors.initials: WM
authors.lastname: Gallagher
mesh_terms: D000178:Acrylamides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D000327:Adsorption; D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001798:Blood Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects*; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D005353:Fibronectins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D022001:Focal Adhesions / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011137:Polystyrenes / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013499:Surface Properties
chemical_list: D000178:Acrylamides; D001672:Biocompatible Materials; D001798:Blood Proteins; D003470:Culture Media; D005353:Fibronectins; D011137:Polystyrenes; D012709:Serum Albumin; C079805:poly(N-isopropylacrylamide-N-tert-butylacrylamide)copolymer; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3