This study was approved by the Ethical Committee of the First Affiliated Hospital of Sun Yat-sen University (Approval Reference Number: 2017-49). Written informed consent was obtained from each infertile couple prior to donating immature oocytes for research. Immature oocytes were donated from patients undergoing intracytoplasmic sperm injection (ICSI) from Mar 2015 to June 2017 at the Reproductive Medical Center of the First Affiliated Hospital of Sun Yat-sen University. Written informed consent was obtained from each donor prior to donating immature oocytes for researches. All of the patients followed a protocol using gonadotrophin-releasing hormone agonist and Gonal-F (Gonal-F; Merck Serono, The Netherlands) for ovarian stimulation (Ding et al., 2015). Oocyte retrieval was carried out 34–36 h after the administration of 10,000 IU HCG (Ovidrel; Merck Serono, The Netherlands). Oocytes lacking a polar body were considered immature (germinal vesicle and metaphase I oocytes) after stripping for intracytoplasmic sperm injection (ICSI) on the day of oocyte retrieval. Only the oocytes remaining at the metaphase I stage were used for in-vitro maturation. Written informed consent was also obtained from the β-thalassemia patients to donate blood and skin fibroblast cells for gene editing research in cells and embryos.