In early September 2025, the National Aeronautics and Space Administration (NASA) announced the launch of an innovative experiment called AVATAR, which stands for A Virtual Astronaut Tissue Analogue Response. In the pursuit of transforming modern medical research, the experiment will use organ chips to investigate how human tissues respond to the microgravity and ionising radiation in space, and aspires to elucidate the potential adverse effects of future Moon and Mars expeditions on the health of individuals, subsequently advancing space exploration research.
Set in motion as a collective effort with United States government and commercial agencies including the National Center for Advancing Translational Sciences (NCATS), the Biomedical Advanced Research and Development Authority (BARDA), Space Tango, and Emulate, Inc.; results obtained from AVATAR could contribute to the development of tailored protective health measures in future explorations for astronauts participating in the Artemis II test flight, a mission that is planned to be launched around the moon by April 2026. In addition to providing critical information on the effects of microgravity and irradiation, these results have extensive applicability beyond space exploration; they can contribute to providing vital information on various disease states, as well as expanding our knowledge of fundamental biological processes such as ageing or DNA damage.
Organ chips, which are marginally longer than a fingertip, are also known as microphysiological systems and are designed to stimulate tissue and organ function in response to specific stimuli. In AVATAR, the thin and compact chips are composed of cells derived from Artemis II astronauts post-platelet donation and will accompany the astronauts on their ten-day trip around the Moon. Platelets are cell fragments present in our blood that play a crucial role in blood clotting, and a minute fraction of stem and progenitor cells generated by the bone marrow may circulate in the blood sample obtained from the participating astronaut, which can be collected to artificially synthesise bone marrow chips to study bone marrow function.
Bone marrow is the tissue found within our bones that can be further divided into two types: red marrow and yellow marrow. The red marrow, in particular, is responsible for the production of different types of blood cells, including red blood cells, which are responsible for transporting oxygen throughout our body, and most notably, white blood cells, which play a prominent role in immunity. This tissue type is most prone to radiation damage, making it a perfect candidate for researching the effects of outer space on human health.
AVATAR bone marrow chips were designed by Emulate, Inc., with Space Tango contributing to the creation of a system that maintains the adjacent nutrient levels and ambient conditions constant. This system allows the organ chips to last in space, and the effects of microgravity and radiation to be studied without confounding factors interfering with the experiment. Following the astronauts’ arrival back to Earth, Emulate, Inc. scientists will use a distinct gene expression analysis procedure called single-cell RNA sequencing, which will provide important information on how each discrete cell within the launched organ chips has been impacted by conditions present in outer space. The results obtained will then be contrasted against a co-occurring immunological study on Earth.
AVATAR organ chips, along with other organ chips being investigated, are paving the way to personalised medicine, and it is only a matter of time before these small technologies make massive strides in scientific research and medical treatment.