1. Julius Wolff Institute; Charité-Universitätsmedizin Berlin; Augustenburger Platz 1 D-13353 Berlin Germany
2. Department of Biomaterials Science and Technology; Twente University; P.O. Box 217 7500 AE Enschede The Netherlands
3. Department of Biomedical Engineering; Eindhoven University of Technology; P.O. Box 513 5600 MB Eindhoven The Netherlands
4. Department of Oral and Maxillofacial Diseases; University of Helsinki; Haartmaninkatu 8 FI00014 Helsinki Finland
5. Max Planck Institute of Colloids and Interfaces; Am Mühlenberg 1 14476 Potsdam Germany
6. Berlin-Brandenburg Center for Regenerative Therapies; Charité-Universitätsmedizin Berlin; Augustenburger Platz 1 D-13353 Berlin Germany
7. Department of Biomedical Engineering; University Medical Centre Groningen; University of Groningen; Antonius Deusinglaan 1 9713 AV Groningen The Netherlands