Mini brains and beating heart tissue head to the ISS to decode how space ages the human body

Tucked inside a shoebox-sized automated laboratory now hurtling toward the International Space Station are up to 16 miniature beating hearts and a collection of peppercorn-sized brain models — the first organs of their kind ever sent into orbit. They launched Tuesday morning from Cape Canaveral Space Force Station aboard SpaceX's CRS-35 cargo mission and are expected to dock with the ISS on Thursday.

Researchers at the Icahn School of Medicine at Mount Sinai, NASA, and aerospace company Space Tango are collaborating on the experiment. The goal is to expose the miniature organs to the microgravity and elevated radiation of low Earth orbit — conditions that, according to the researchers, compress a decade or two of human aging into a single six-month mission.

Six months in space ... is equivalent to about 10 to 20 years of aging on Earth.— Kevin Costa, Associate Professor of Surgery, Icahn School of Medicine at Mount Sinai

That compression is precisely what makes the mission scientifically valuable. Rather than waiting years to observe how aging damages tissue, researchers can watch the same process unfold in weeks inside the space station — and then translate those findings into treatments for people on Earth.

If people are going to be living and working in space, then we need to understand what's going to happen to them. But also, because it's interesting as a model of accelerated aging for studying people on Earth.— David Sachs, Assistant Professor of Surgery, Icahn School of Medicine at Mount Sinai

The miniature hearts will be tested for how they respond to electrical signals and how they behave in near-zero gravity. Alongside them are the miBrains — small three-dimensional models representing both healthy and diseased brain tissue — which scientists will use to study neurological processes linked to Alzheimer's, Parkinson's, and multiple sclerosis, according to India Today.

[The research is] translating to stuff in space, but it's also translating back to the research we do in the laboratory to help people with Parkinson's and Alzheimer's disease.— Joel Blanchard, Associate Professor of Stem Cell Biology and Regenerative Medicine and Neuroscience, Icahn School of Medicine at Mount Sinai

The organs travel inside a device called CubeLab, developed by Space Tango. It is a fully automated, miniaturized system that simulates the natural environment of the human body — maintaining temperature, regulating gases, and keeping the tissue alive without any crew intervention.

[It is] slightly bigger than a shoebox, and it is a fully automated, miniaturized system.— Gentry Barnett, Chief Technology Officer, Space Tango

The CRS-35 mission is also carrying hardware to manufacture artificial retinas in microgravity, materials to study how a new type of glass forms without gravity, and the final set of roll-out solar arrays for the ISS, according to India Today. The Dragon spacecraft is expected to remain docked until mid-November before splashing down off the coast of California with research samples aboard.

This is not Mount Sinai's first foray into space biology. The university's Cardiovascular Research Institute dispatched individual heart cells to the ISS in 2023, where those cells proved capable of surviving in the weightless environment. The new mission goes further, sending structured, functional tissue models rather than isolated cells.

The microgravity environment also offers a unique window into conditions that are hard to replicate on Earth. Sachs noted that what happens to the body in space closely mirrors what happens during prolonged bed rest or a sedentary lifestyle — making the ISS an unexpected laboratory for studying those populations too.

A parallel and related effort flew on the Artemis II mission, which recently returned from a loop around the far side of the moon. That project, called AVATAR (A Virtual Astronaut Tissue Analog Response), used organ-on-a-chip devices — roughly the size of a USB drive — containing bone marrow tissue grown from cells donated by each of the four Artemis II crew members, according to NASA and The Scientist. Among all organs in the human body, bone marrow is the most sensitive to radiation and serves as the source of every blood and immune cell. Those chips experienced the same radiation, weightlessness, and launch forces as the astronauts themselves.

The AVATAR chips have now returned to Earth, where scientists at Emulate — the company that commercialized the organ-chip technology developed at the Wyss Institute at Harvard — are analyzing them using single-cell RNA sequencing, a technique that measures how thousands of genes change within individual cells, according to NASA. Results will be compared against ground-control chips that stayed on Earth and against pre- and post-flight blood samples from the astronauts.

NASA leads the AVATAR project in partnership with the Biomedical Advanced Research and Development Authority (BARDA) and the National Center for Advancing Translational Sciences (NCATS), part of the National Institutes of Health. Space Tango built the hardware that kept the chips alive inside the Orion capsule, a significant engineering challenge given Orion's strict limits on electrical power and mass, according to The Scientist.

For NASA, both lines of research feed into a longer-term goal: protecting astronauts on missions that go far beyond the ISS. A crewed lunar surface landing is targeted for 2028, and the agency has also discussed partnering with SpaceX to send humans to Mars.

We're making leaps, not incremental research, by taking biology to space, because you're seeing changes that you cannot see on the ground in ways you've never seen it before.— Lisa Carnell, Director, Biological and Physical Sciences Division, NASA

We sent Apollo astronauts out there over 50 years ago, but the techniques and the way that we can actually do assessments to understand what's happening has come a long way since then.— Lisa Carnell, Director, Biological and Physical Sciences Division, NASA

If the organ chips can reliably predict how individual astronauts respond to radiation and microgravity, NASA envisions using them to build personalized medical kits for future deep-space crews — a practical application that could also reshape how drug testing and personalized medicine work on Earth, according to NASA.

Why it matters — Understanding how space accelerates aging in living tissue could protect astronauts on moon and Mars missions — and the same findings may speed up treatments for Alzheimer's, Parkinson's, heart disease, and other conditions on Earth.

Reported by mountsinai.org, abcnews.com, rollingout.com, indiatoday.in, the-scientist.com, science.nasa.gov, 3dnatives.com, washingtonpost.com