1. College of Life Sciences, Northeast Agricultural University , Harbin 150030 , China
2. State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences , Beijing 100101 , China
3. Institute for Stem Cell and Regenerative Medicine, Chinese Academy of Sciences , Beijing 100101 , China
4. Savaid Medical School, University of Chinese Academy of Sciences , Beijing 100049 , China
5. University of Chinese Academy of Sciences , Beijing 100049 , China
6. Beijing Institute for Stem Cell and Regenerative Medicine , Beijing 100101 , China