1. Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China.
2. Department of Endodontics, College of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi, China.
3. Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China.
4. State Key Laboratory of Cancer Biology and Institute of Digestive Diseases, Department of Gastroenterology, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China.
5. Department of Oral Histology and Pathology, College of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi, China.