1. Department of Biomedical Engineering and ‡Korea University & Korea Institute of Science and Technology (KU-KIST) Graduate School of Converging of Sciences & Technologies, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713, Republic of Korea
2. Department of Nanobiomedical Science & BK21 Plus NBM Global Research Center for Regenerative Medicine and ∥Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Anseo-dong, Dongnam-gu, Cheonan 330-714, Republic of Korea