Received: 26 November 2019
Accepted: 3 February 2020
First Online: 10 February 2020
Ethics approval and consent to participate
: None of the cell lines used in the present study required ethics approval for their use. All experiments involving cytotrophoblasts and a choriocarcinoma tissue specimen were approved by the Ethical Committee of the Jobu University (No.17-H01) and the institutional review board of the Faculty of Medicine, University of Tokyo (IRB number: 10580), and written informed consent was obtained from each participant. Animal experiments were approved by the Animal Experiment Committee of Jobu University (No.16-AN03) and Animal Care and Experimentation Committee of Gunma University (No.16–049).
: Not applicable.
: MS received research funding from Denka Seiken Co. Ltd. The other authors state no conflict of interest for this research.