In vitro Response of Human Mesenchymal Stromal Cells to Titanium Coated Peek Films and Their Suitability for Magnetic Resonance Imaging Cindy Elschner 1 , * , Carolin Noack 2 , Carolin Preißler 3 , Andreas Krause 4 , Ulrich Scheler 1 , * , Ute Hempel 3 1 Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden, Germany 2 CRTD/DFG-Center for Regenerative Therapies Dresden, Fetscherstr. 105, 01307 Dresden, Germany 3 Institut für Physiologische Chemie, Technische Universit€ at Dresden, Fiedlerstr. 42, 01307 Dresden, Germany 4 NaMLab gGmbH, N€ othnitzer Str. 64, 01187 Dresden, Germany article info Article history: Received 24 July 2014 Received in revised form 25 September 2014 Accepted 22 October 2014 Available online 4 April 2015 Key words: Polyetheretherketone Titanium coating Biocompatibility Magnetic resonance imaging Human mesenchymal stromal cells Medical imaging is an important tool for the post-operative checkup of an accurate position of an implant as well as for monitoring the integration in the adjacent tissue that may influence the success of a medical device. Unfortunately, the possibility to use imaging methods is associated with the implant material and all the established metallic materials for surgery do not show a proper “imaging compat- ibility”. The present study is a combined investigation of the in vitro response to human mesenchymal stromal cells (hMSC) and magnetic resonance imaging (MRI) compatibility of the potential material combination polyetheretherketone/titanium (PEEK/Ti) for medical devices. Because of the advantageous imaging properties and the mechanical and chemical stability, PEEK becomes more and more an alter- native to common metallic implant materials like titanium or cobalt‒chrome. However, PEEK is a bioinert material having a limited ability for direct bone incorporation. Due to its excellent biocompatibility, Ti was chosen as coating material to enhance the cellular response. The result is a combination with ad- vantageous properties: the magnetic susceptibility and elastic modulus close to bone, corrosion resis- tance and mechanical flexibility of PEEK and the excellent biocompatibility of titanium. The appearance of metal-related artifact was discussed in electrical resistivity and magnetic susceptibility. Therefore, two titanium coatings have been investigated: a complete coating and a structured surface avoiding surface conductivity. To determine the in vitro biocompatibility, the cell responses were assessed in terms of the overall morphology of the hMSC and their cell area distribution, proliferation, osteogenic differentiation and mineral deposition. The cellular stress was evaluated by the prostaglandin E 2 level. The bonded materials both produced no disturbing artifacts in magnetic resonance imaging. Compared to the pure PEEK material, the titanium coated specimens showed an enhanced biocompatibility, which is indicated by a higher cell number, larger activity of the enzyme tissue non-specific alkaline phosphatase and therefore a greater amount of deposited calcium and phosphate. The results on bare PEEK are accom- panied with a higher cellular stress level, which is indicated by prostaglandin E 2 . Copyright © 2015, The editorial office of Journal of Materials Science & Technology. Published by Elsevier Limited. All rights reserved. 1. Introduction Biomaterials must fulfill various requirements to serve as an appropriate material for implants, prostheses or artificial organs. In the optimal case, the chemical and physical properties of the material correspond well with the replaced tissue and therefore design and material properties depend on the intended application. The foremost condition is biocompatibility of the material due to interactions of the foreign matter and the surrounding host tissue and body fluids. The material must not be toxic and must not cause any allergic or inflammatory reactions due to chemical inertness, which are the most important issues. Moreover, the success of an implant also depends on the mechanical and structural compati- bility. The properties, such as hardness, elastic modulus and fatigue strength are crucial for the longevity; the integration in the * Corresponding authors. Tel.: þ49 351 4658 432; Fax: þ49 351 4658 231. E-mail addresses: cindy.elschner@gmx.de (C. Elschner), scheler@ipfdd.de (U. Scheler). Contents lists available at ScienceDirect Journal of Materials Science & Technology journal homepage: www.jmst.org http://dx.doi.org/10.1016/j.jmst.2014.10.012 1005-0302/Copyright © 2015, The editorial office of Journal of Materials Science & Technology. Published by Elsevier Limited. All rights reserved. Journal of Materials Science & Technology 31 (2015) 427e436