Qiquan Sun1, Xinpu Gao2, Dicken Shiu-Chung Ko3, Xian Chang Li4. 1. Division of Renal Transplantation, Third Affiliated Hospital, Sun Yat-sen University, Guangzhou 510530, China. Electronic address: sunqiquan@hotmail.com. 2. China Organ Donation Administrative Center, Beijing, China. 3. Department of Urology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. 4. Immunobiology and Transplantation Research, Houston Methodist Hospital, Texas Medical Center, Houston, TX, USA.