Funding for this research was provided by:
National Natural Science Foundation of China (81471399)
Received: 13 December 2017
Revised: 25 February 2018
Accepted: 6 March 2018
First Online: 3 April 2018
Ethics approval and consent to participate
: This work was submitted to and approved by the Ethics Committee of Xinhua Hospital Affiliated to Shanghai Jiao Tong University. Umbilical cord blood was obtained after written informed consent was signed by mothers.
: Not applicable.
: The authors declare that they have no competing interests.
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