1. Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, California 90095, United States
2. Department of Mechanical Engineering and Material Science, Duke University, Durham, North Carolina 27708, United States
3. Department of Medicine, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul 135-710, Korea
4. Department of Pathology and Translational Genomics, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul 135-710, Korea
5. Department of Surgery, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul 135-710, Korea
6. Department of Bioengineering, University of California, Riverside, Riverside, California 92521, United States
7. UCLA School of Dentistry, 10833 Le Conte Ave. Box 951668, Los Angeles, California 90095-1668, United States