1. State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences 1 , 100101 Beijing , China
2. Institute for Stem Cell and Regeneration, Chinese Academy of Sciences 2 , 100101 Beijing , China
3. Beijing Institute for Stem Cell and Regenerative Medicine 3 , 100101 Beijing , China
4. Savaid Medical School, University of Chinese Academy of Sciences 4 , 100101 Beijing , China