SHENZHEN — Mouse embryo samples returned to Earth aboard China’s Shenzhou XXII spacecraft are set to advance research on mammalian embryonic development in space and lay groundwork for potential human conception during extended space missions.

The Shenzhou XXII capsule returned to Earth on May 29, bringing back cultured mouse embryos that underwent developmental observation aboard the Tiangong space station. The experimental samples were part of a project led by researchers from the Shenzhen Institutes of Advanced Technology (SIAT), under the Chinese Academy of Sciences.

The study aims to investigate how mammalian pre-implantation embryos develop in microgravity, with a focus on the mechanisms of mitochondrial damage and epigenetic modification abnormalities induced by the space environment. The research could shed light on the feasibility of natural reproduction during long-term human habitation beyond Earth.

A key figure in the experiment, Lei Xiaohua, senior researcher at SIAT’s Institute of Biomedicine and Biotechnology, highlighted the technical challenges of culturing and imaging embryos in the restricted confines of 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.

To meet these requirements, the team collaborated with researchers led by Men Yongfan from SIAT’s Research Center for Biomedical Optics and Molecular Imaging. Together, they developed a microfluidic chip culture device featuring two rows of six chambers, allowing for parallel experiments with multiple replicates. This system was fully integrated with the space station’s automated culture infrastructure.

Prior to launch, the experimental setup underwent comprehensive ground-based verification to ensure functionality for embryo culture, imaging, perfusion fixation, and cryopreservation under space conditions. During the mission, clear images of embryo development were successfully captured, and sample fixation and preservation were confirmed to be optimal.

Following retrieval from the Shenzhou XXII capsule on May 30, the live samples were transported under refrigerated conditions to the Chinese Academy of Sciences’ Technology and Engineering Center for Space Utilization in Beijing for detailed analysis.

Future work will involve systematic comparisons between space-exposed samples and ground controls, incorporating developmental phenotype assessments, protein molecular staining, high-resolution chromatin 3D imaging, and multi-omics sequencing techniques. This comprehensive approach aims to clarify the impact of the space environment on crucial stages such as zygotic genome activation and early embryonic development.

Lei Xiaohua, who previously participated in two landmark Chinese space embryo experiments, noted the significance of this research in expanding understanding of life’s developmental patterns beyond Earth. Earlier milestones include the 2006 real-time imaging of embryos aboard the Shijian 8 satellite and the complete development of mouse embryos from the 2-cell stage to blastocyst in space during the 2016 Shijian 10 mission.

The current findings promise foundational insights as China continues to explore the biological challenges of long-duration spaceflight and human reproduction in extraterrestrial environments.