Evaluation of the post-implantation development of mouse embryos derived from round spermatid injection

Round spermatid injection (ROSI), one of the assistant reproductive technologies, was used to treat partial infertility patients suffering from non-obstructive azoospermia. However, the development efficiency and birth rate of ROSI embryos are extremely low, and it is urgent to investigate the underlying mechanisms of low efficiency to improve the clinical application of ROSI technology. Here, we analyzed and compared the genome stability of the mouse blastocyst and the post-implantation development between ROSI and ICSI embryos. We first sequenced the genome of blastocysts from mouse ROSI embryos that can correctly form male and female pronuclei (2 PN) and found that the genomes of 7 blastocysts were normal. Furthermore, the implantation rate of ROSI 2 PN embryos on embryonic day 7.5 is similar to that of ICSI embryos, and at this time, 37.50% (9/24) of deciduas have no normal gestational sac. The proportion of embryos that survived to embryonic day 11.5 in the ROSI 2 PN group, ROSI non-2 PN group, parthenogenesis group, and ICSI 2 PN group was 51.61%, 7.14%, 0.00%, and 55.00%, respectively. And two smaller fetuses were found in the ROSI 2 PN group, which is not found in the other three groups. In addition, the physiological indexes, including fetus and placenta weight, sex ratio, growth rate, and the natural breeding ability for the offspring obtained from mouse ROSI, were evaluated; ROSI mice exhibited no obvious defect or abnormality and implied that the progeny were safe. Our results provided new evidence to promote the clinical application of ROSI technology.