Funding for this research was provided by:
General Research Fund of the Research Grants Council, Hong Kong (GRF 17158316)
National Natural Science Foundation of China-Swedish Research Council Collaboration Research Programme (NSFC-VR 3181101648)
the Shenzhen Knowledge Innovation Programme of the Shenzhen Science and Technology Innovation Commission (20180264)
The University of Hong Kong-Shenzhen Hospital Scientific Research Training Plan (HKUSZH20192003)
Received: 22 March 2021
Accepted: 25 April 2021
First Online: 29 May 2021
Change Date: 5 May 2022
Change Type: Correction
Change Details: A Correction to this paper has been published:
Change Details: https://doi.org/10.1186/S13287-022-02872-6
: Ethical approval was obtained from the Institutional Review Board of The University of Hong Kong/Hospital Authority Hong Kong West Cluster (IRB reference number UW15-128). Each woman signed a written consent after full counseling.
: Written informed consent was obtained from the donors for recording/using their individual details (age and gender) for research purposes.
: The authors declare no competing interests.