Comparison of mesenchymal stem cell proliferation and differentiation between biomimetic and electrochemical coatings on different topographic surfaces Elena Garcı ´a-Gareta • Jia Hua • Jonathan C. Knowles • Gordon W. Blunn Received: 11 July 2012 / Accepted: 3 October 2012 Ó Springer Science+Business Media New York 2012 Abstract The hypothesis for this study was that there is no difference in mesenchymal stem cells (MSCs) prolif- eration and osteogenic differentiation between calcium- phosphate (CaP) coatings with different crystal size deposited on different topographic surfaces of metal discs. Polished (P) and sand-blasted (SB) tantalum and TiAl6V4 discs were CaP coated by three methods—biomimetic (BioM), electrochemical at 20 mA/cm 2 and at 6.5 mA/ cm 2 —and cultured with MSCs. At days 4, 7 and 14, cell proliferation—alamarBlue Ò activity and DNA quantifica- tion—and differentiation down the osteogenic lineage— ALP activity normalised per amount of DNA and SEM (morphology)—were analysed. Results showed that MSCs proliferated more when cultured on the nano-sized BioM coatings compared to uncoated and electrochemically coated discs. MSCs also proliferated more on P surfaces than on SB and or electrochemical coatings. All the coat- ings induced osteogenic differentiation, which was greater on electrochemical coatings and SB discs. 1 Introduction Metals such as titanium alloys or tantalum are widely used in orthopaedic implants due to their excellent mechanical properties and biocompatibility [1–4]. However, these materials are not osteoconductive. On the other hand, cal- cium phosphate (CaP) ceramics have been shown to form a direct bond with bone tissue through formation of an apatite layer when used for bone substitution, augmentation and repair [5]. Therefore, by coating the surface of metal implants with a CaP layer a bioactive and osteoconductive surface can be created [6]. The most common commercial method for CaP coating of metal implants is plasma-spraying, which is a line- of-sight process that takes place at high temperatures. Disadvantages of this method are the formation of easily dissolved phases; it does not allow the incorporation of bioactive molecules and cannot be applied to implants with complex morphology. Other methods have been developed to overcome these disadvantages, such as the biomimetic and electrochemical depositions. Both methods are based on precipitation from aqueous solutions (wet methods), take place at low temperature, allow the coating of com- plex shapes and are economical. The biomimetic method, originally developed by Kokubo et al. [7, 8] in the 1990s , uses simulated body fluids (SBF) that mimic physiological ionic strength and pH and many procedures and recipes can be found in the literature [9–11]. In a typical electro- chemical deposition, a precursor is first formed that is converted into hydroxyapatite (HA) through an ageing process. Thus this method offers a control over deposit crystallinity [12, 13]. Bone marrow stromal cells or mesenchymal stem cells (MSCs) have been shown to differentiate into bone, as well as cartilage and fat cells [14], which makes them ideal candidates for developing bone tissue-engineered con- structs. It is well known that CaP materials promote MSCs differentiation down the osteogenic lineage [15–17] and that surface topography and particle size have an effect on E. Garcı ´a-Gareta (&) Á J. Hua Á G. W. Blunn John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, University College London, Royal National Orthopaedic Hospital, Stanmore, HA7 4LP, UK e-mail: garcia.elenita@googlemail.com; elena.garcia@ucl.ac.uk J. C. Knowles Eastman Dental Institute, University College London, 256 Gray’s Inn Road, London WC1X 8LD, UK 123 J Mater Sci: Mater Med DOI 10.1007/s10856-012-4789-x