1. Department of Endodontics, School of Stomatology, China Medical University, Shenyang, Liaoning 110002, P.R. China
2. Department of Stem Cells and Regenerative Medicine, Key Laboratory of Cell Biology, Ministry of Public Health of China, China Medical University, Shenyang, Liaoning 110013, P.R. China
3. Department of Anal and Intestinal Surgery, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China