Mouse embryo material brought back to Earth aboard the Shenzhou XXII return capsule is expected to provide a theoretical foundation for future research on conceiving life during long-term human space habitation.

The Shenzhou XXII successfully made it back from the Tiangong space station on May 29. The cultured embryo material was among science samples brought back as part of a project undertaken by a research team from the Chinese Academy of Sciences' Shenzhen Institutes of Advanced Technology.

According to SIAT, the experiment aims to explore developmental patterns of mammalian pre-implantation embryos in a space environment, including the key mechanisms underlying mitochondrial damage and epigenetic modification abnormalities in embryos.

Led by a senior researcher, Lei Xiaohua, from the center for energy metabolism and reproduction of SIAT's Institute of Biomedicine and Biotechnology, the team performed the in-orbit culture of mouse embryos, at various developmental stages, using a biotechnology experiment cabinet on the space station.

"Given the strict constraints on spaceship transfer and in-orbit resources, the core challenge of this experiment was how to achieve embryo culture and real-time imaging within limited space," Lei said.

The team collaborated with another SIAT team, led by Men Yongfan from the Research Center for Biomedical Optics and Molecular Imaging, to design an embryo microfluidic chip culture box. It featured two rows of six culture chambers. This design simultaneously met the needs of two experimental groups — each with three replicate experiments — and was compatible with the space station's automated culture system.

After ground-based verification tests, the team established a complete experimental system for mammalian pre-implantation embryo culture, imaging, perfusion fixation, and cryopreservation suitable for the space station.

The team confirmed that in-orbit embryo development images were successfully captured, and that embryo development, as well as fixation and preservation conditions, were optimal.

In the early morning of May 30, live science experiment samples retrieved from the Shenzhou XXII return capsule were transported to the Technology and Engineering Center for Space Utilization of the Chinese Academy of Sciences in Beijing via specialized refrigeration equipment.

In future research, Lei's team will conduct systematic comparison and integrated analysis of the returned samples and ground-based control samples, including developmental phenotype statistics, specific protein molecular staining, high-resolution chromatin three-dimensional imaging, and multi-omics sequencing.

The research will provide key data when determining space's influence on zygotic genome activation stage and whether the space environment can support normal early development, thereby deepening our understanding of the initial developmental patterns of mammalian life in the space environment, he said.

Lei has earlier participated in two major space embryo experiments of the country. In 2006, a Chinese research team achieved real-time imaging of space embryos from the ground for the first time via the Shijian 8 satellite.

In 2016, China's Shijian 10 satellite carried early mouse embryos into space, for the first time achieving the complete development in space of mouse embryos from the 2-cell stage, an early-on embryonic cleavage stage, to blastocyst, the stage where noticeable cell differentiation occurs.