Role of non-canonical Wnt signaling in osteoblast maturation on microstructured titanium surfaces

• Type of Material: Article
• Authors: Rene Olivares-Navarrete, Georgia Institute of Technology; Sharon L. Hyzy, Georgia Institute of Technology; Daphne L. Hutton, Georgia Institute of Technology; Ginger R. Dunn, Georgia Institute of Technology; Christoph Appert, Institut Straumann AG; Barbara Boyan, Emory University; Zvi Schwartz, Georgia Institute of Technology
• Language: English
• Date: 2011-06-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: Copyright © 2011 Published by Elsevier Ltd.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.actbio.2011.02.030
• Title of Journal or Parent Work: Acta Biomaterialia
• ISSN: 1742-7061
• Volume: 7
• Issue: 6
• Start Page: 2740
• End Page: 2750
• Grant/Funding Information: Titanium disks were provided by Institut Straumann AG (Basel, Switzerland) as a gift.; This project was supported by a grant from the National Institute of Arthritis, Musculoskeletal, and Skin Diseases at the National Institutes of Health (USPHS Grant AR052102).
• Keywords: Engineering; Regulatory factors; STEM-CELLS; Materials Science; PATHWAY; BONE-FORMATION; Titanium surface roughness; C3H10T1/2 MESENCHYMAL CELLS; CATENIN; Technology; PROTEIN; DIFFERENTIATION; MICRON-SCALE; Engineering, Biomedical; RECEPTOR TYROSINE KINASE; Osteoblast differentiation; Science & Technology; Gene expression; Materials Science, Biomaterials; ROR2; Cell signaling
• Research Categories: Engineering, Biomedical; Biology, Cell

Abstract

The Wnt signaling pathway inhibitor Dickkopf-2 (Dkk2) regulates osteoblast differentiation on microstructured titanium (Ti) surfaces, suggesting involvement of Wnt signaling in this process. To test this, human osteoblast-like MG63 cells were cultured on tissue culture polystyrene or Ti (smooth PT (Ra = 0.2 μm), sand-blasted and acid-etched SLA (Ra = 3.22 μm), modSLA (hydrophilic SLA)). Expression of Wnt pathway receptors, activators and inhibitors was measured by qPCR. Non-canonical pathway ligands, receptors and intracellular signaling molecules, as well as bone morphogenetic proteins BMP2 and BMP4, were upregulated on SLA and modSLA, whereas canonical pathway members were downregulated. To confirm that non-canonical signaling was involved, cells were cultured daily with exogenous Wnt3a (canonical pathway) or Wnt5a (non-canonical pathway). Alternatively, cells were cultured with antibodies to Wnt3a or Wnt5a to validate that Wnt proteins secreted by the cells were mediating cell responses to the surface. Wnt5a, but not Wnt3a, increased MG63 cell differentiation and BMP2 and BMP4 proteins, suggesting Wnt5a promotes osteogenic differentiation through production of BMPs. Effects of exogenous and endogenous Wnt5a were synergistic with surface microstructure, suggesting the response also depends on cell maturation state. These results indicate a major role for the non-canonical, calcium-dependent Wnt pathway in differentiation of osteoblasts on microstructured titanium surfaces during implant osseointegration.