China sends human embryo models into space for groundbreaking experiment

With the successful launch of the Tianzhou 10 cargo spacecraft on Monday, human embryo models have been sent into space, marking the world's first in-situ experiment to explore the possible effects of microgravity and radiation on human early embryonic development in an actual space conditions — a crucial step toward understanding whether humans may one day live and reproduce in space.

The mission is expected to help establish a technical framework for studying artificial embryo development in space.

The human embryo model is an "embryo-like structure" built from stem cells that closely resembles a natural human early embryo, offering advantages such as fewer ethical restrictions, high yield and good reproducibility. It exhibits remarkable differentiation potential and possesses the most critical mechanisms underlying early human development.

They are not real embryos and cannot develop into a human being.

Yu Leqian, a professor at the Institute of Zoology under the Chinese Academy of Sciences and head of the human embryo model space project aboard Tianzhou 10, said that human embryo models now cover the developmental stage from day 14 to day 21 after human fertilization.

"This stage is a critical window in early human development, during which organ precursors begin to form and the entire body axis — determining which side becomes the head and which becomes the tail — is established," Yu said, noting that any disturbance or abnormality at this stage may have a profound impact on the adult individual.

"Therefore, the embryo models are brought to space to explore whether life, which has evolved under gravity for hundreds of millions of years, would be affected by the sudden absence of gravity," he added.

The current ground-simulated environment still falls short of real space conditions. For example, in rotating culture experiments, researchers can only change the direction of gravity but cannot eliminate it, while drop towers provide only seconds of microgravity during free fall — far too short to cover days of embryo development.

This launch provides a rare true microgravity environment with actual space radiation, where the embryo models are expected to follow the natural course of embryonic development once in orbit. The culture medium will be automatically replaced daily as preset program, allowing the embryos to complete five days of development, after which the samples will be frozen and stored for analysis upon their return to Earth.

Two types of models are being carried to the China Space Station — a peri-implantation model and a peri-gastrulation model. They represent two key periods of the attachment of the embryo models to the uterine cells, and a key event during early development — gastrulation.

"By comparing embryo development in space and on the ground, we can investigate the impact of the space environment on critical events in human embryogenesis, assess how well embryo models can substitute for natural embryos in space development studies, and thus establish a technical basis for research on human embryonic development in space," Yu said.

He also highlighted the importance of the research in helping reveal the risks and challenges that future humans may face when living in space for extended periods, as well as issues related to human reproduction during long-term space habitation, laying the groundwork for humanity's reproduction in space.

Additionally, by comparing development in space and on Earth, the research may also reveal which diseases are linked to abnormalities in early embryonic development, he added.