Luo, Qianqian
Liu, Ranran
Wang, Li
Hou, Yun
Zhang, Hongqin
Article History
Received: 21 August 2019
Accepted: 25 September 2019
First Online: 28 January 2020
Compliance with Ethical Standards
: The use of human placentas tissue was permitted to the Institutional Ethics Committee of Binzhou Medical University.
: The authors declare that they have no conflict of interest.