1. Center for Cellular and Molecular Engineering, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
2. McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
3. Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, Pennsylvania.
4. Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
5. School of Medicine, Tsinghua University, Beijing, China.