1. Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
2. St Hugh's College, St Margaret's Road, Oxford OX2 6LE, UK
3. Laboratory for Neurobiology and Gene therapy, Katholieke Universiteit Leuven, Kapucijnenvoer 33i (7001), 3000 Leuven, Belgium
4. Biomechanics Research Unit, Université de Liège, Chemin des Chevreuils 1 B52/3, 4000 Liège, Belgium
5. Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, Herestraat 49, 3000 Leuven, Belgium