title: Screening rat mesenchymal stem cell attachment and differentiation on surface chemistries using plasma polymer gradients.
abstract: It is well known that the surface chemistry of biomaterials is important for both initial cell attachment and the downstream cell response. Surface chemistry gradients are a new format that allows the screening of the subtleties of cell-surface interactions in high throughput. In this study, two surface chemical gradients were fabricated using diffusion control during plasma polymerization via a tilted mask. Acrylic acid (AA) plasma polymer gradients were coated on a uniform 1,7-octadiene (OD) plasma polymer layer to generate OD-AA plasma polymer gradients, whilst diethylene glycol dimethyl ether (DG) plasma polymer gradients were coated on a uniform AA plasma polymer layer to generate AA-DG plasma polymer gradients. Gradient surfaces were characterized by X-ray photoelectron spectroscopy, infrared microscopy mapping, profilometry, water contact angle (WCA) goniometry and atomic force microscopy. Cell attachment density and differentiation into osteo- and adipo-lineages of rat-bone-marrow mesenchymal stem cells (rBMSCs) was studied on gradients. Cell adhesion after 24 h culture was sensitive to the chemical gradients, resulting in a cell density gradient along the substrate. The slope of the cell density gradient changed between 24 and 6 days due to cell migration and growth. Induction of rBMSCs into osteoblast- and adipocyte-like cells on the two plasma polymer gradients suggested that osteogenic differentiation was sensitive to local cell density, but adipogenic differentiation was not. Using mixed induction medium (50% osteogenic and 50% adipogenic medium), thick AA plasma polymer coating (>40 nm thickness with ∼11% COOH component and 35° WCA) robustly supported osteogenic differentiation as determined by colony formation and calcium deposition. This study establishes a simple but powerful approach to the formation of plasma polymer based gradients, and demonstrates that MSC behavior can be influenced by small changes in surface chemistry.
authors.affiliation: Department of Chemical Engineering, National Taiwan University, No. 1, Roosevelt Rd, Sec. 4, Taipei 106, Taiwan; Industrial Research Institute Swinburne (IRIS), and Department of Chemistry and Biotechnology, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, 3122 VIC, Australia; CSIRO Materials Science and Engineering, Bayview Avenue, Clayton, 3168 VIC, Australia.
authors.forename: Peng-Yuan
authors.initials: PY
authors.lastname: Wang
authors.affiliation: School of Chemical and Physical Sciences, Flinders University, Bedford Park, 5042 SA, Australia.
authors.forename: Lauren R
authors.initials: LR
authors.lastname: Clements
authors.affiliation: CSIRO Materials Science and Engineering, Bayview Avenue, Clayton, 3168 VIC, Australia.
authors.forename: Helmut
authors.initials: H
authors.lastname: Thissen
authors.affiliation: Department of Chemical Engineering, National Taiwan University, No. 1, Roosevelt Rd, Sec. 4, Taipei 106, Taiwan.
authors.forename: Wei-Bor
authors.initials: WB
authors.lastname: Tsai
authors.affiliation: ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Mawson Institute, University of South Australia, Mawson Lakes, 5095 SA, Australia. Electronic address: nico.voelcker@unisa.edu.au.
authors.forename: Nicolas H
authors.initials: NH
authors.lastname: Voelcker
mesh_terms: D000818:Animals; D063566:Biodegradable Plastics / Q000494:pharmacology*; D002448:Cell Adhesion; D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D005260:Female; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D010012:Osteogenesis / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D063566:Biodegradable Plastics
keywords: Differentiation; Mesenchymal stem cells; Plasma polymers; Surface chemistry; Surface-bound gradients