Mouse stem cells on board an unmanned Chinese space craft divided and reproduced significantly faster than others grown back on Earth, scientists have revealed.

In a paper published in the journal Stem Cells and Development, a team led by Hong Li of the Academy of Military Medical Sciences in Beijing, China, details the development of mouse induced pluripotent stem cells (iPSCs) grown in a specially designed bioreactor on board the Tianzhou-1, which was launched in April 2017.{%recommended 6856%}

The craft, the first of its kind, successfully docked with China’s orbiting space laboratory, Tiangong-2, two days after launch. It was jettisoned in September, then underwent a series of navigational twists and turns to ensure that it burned up in the Earth’s atmosphere.

Before it did so, however, Li and his colleagues were afforded the opportunity to watch a live video feed of the mouse stem cells.

The cells were coded to differentiate into cardiomyocytes, the cells that make up heart muscles. The scientists report that they differentiated and developed “significantly quicker in space” compared to control cells on Earth.

The difference in performance, the researchers say, is because the cells on board Tianzhou-1 were in microgravity, although quite why this should be the case is still unknown.

It is a question now demanding an urgent answer, for reasons of both practicality and profit.

“Understanding how real [microgravity] in outer space affects mammalian stem cell function will facilitate future human space travel,” the Li and colleagues write.

Before that occurs, however, there are other potential benefits to be gained by repeating and refining the experiments on the next few missions.

“In the future, similar automated stem cell experiments may help to realise personalised cardiac tissue biomanufacturing and drug test during space travel,” the researchers note.