News

Published: 09 July 2026

Human cell models reveal the effects of weightlessness

Until now, countless animals have suffered in research into bone loss in zero gravity. A pioneering project by the Greifswald University Medicine for the private space station HAVEN-1 now demonstrates that there is a more precise and ethical approach: research conducted entirely without animal experiments, using exclusively human cell models in orbit.

Zero gravity places the human body under extreme physiological stress. The skeletal system is particularly affected, with astronauts losing up to two percent of their bone mass each month. To investigate the underlying mechanisms and develop countermeasures, space medicine has often relied on animal experiments. For example, mice are subjected to severe stress either in space or in so-called hindlimb unloading experiments on Earth, where they are suspended by their hind legs for weeks to simulate the effects of weightlessness. However, the scientific relevance of these experiments is highly questionable because rodent bone metabolism differs significantly from that of humans.

This is precisely where the project by Greifswald University Medicine and Stralsund University of Applied Sciences comes in. Instead of using animals, the researchers work with human bone cells obtained from patients and tissue banks. On board of the HAVEN-1 space station, they are investigating the so-called mechanostat principle, the process by which bone is lost in the absence of mechanical stress. To model this process, they use 3D bioprinting to create complex biological tissue models. Inside a high-tech incubator in orbit, the researchers precisely analyze how microgravity disrupts communication between osteocytes, which sense mechanical load, and osteoblasts, which are responsible for bone formation. At the same time, control experiments are being conducted in Cologne. The resulting data are essential for the health of astronauts and also offers entirely new treatment approaches for patients with osteoporosis.

The fact that this sophisticated research project is conducted entirely without animal suffering demonstrates an important paradigm shift. Complex biomedical questions can be answered in space using advanced human in vitro methods such as 3D tissue cultures and multi-organ systems. As the documentary Future Science (www.futuresciencefilm.de) compellingly illustrates, human-based high-tech methods are the key to reliable scientific research and are replacing the systematically flawed model of animal experimentation – both on Earth and in space.

References

Vorpommern forscht 2027 im Weltraum, Universitätsmedizin Greifswald 01.06.2026 >>