1 Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA 19104, USA. janmey@pennmedicine.upenn.edu vshenoy@seas.upenn.edu and Department of Materials Science and Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA.
2 Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA 19104, USA. janmey@pennmedicine.upenn.edu vshenoy@seas.upenn.edu and Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA and McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, PA 19104, USA.
3 Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA 19104, USA. janmey@pennmedicine.upenn.edu vshenoy@seas.upenn.edu and Institute for Medicine and Engineering, University of Pennsylvania, 3340 Smith Walk, Philadelphia, PA 19104, USA and Departments of Physiology, and Physics & Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA.