March 20, 2023
Experiments to Study Gravity's Effect on Bone Cells Head to International Space Station

Experiments to Study Gravity’s Effect on Bone Cells Head to International Space Station

Nadab Wubshet, a 5th year ME PhD student in Prof. Allen Liu’s lab, holding up a microfluidic chip that will be sent to the International Space Station. Credit: Samuel Chen / University of Michigan

A pair of experiments to explore bone density, designed by engineers at the University of Michigan, left the Wallops Island, Virginia, launch site on a Northrop Grumman Corp. rocket. Antares for the International Space Station (ISS).

Allen Liu, UM associate professor of mechanical engineering, and members of his research team detail how experiments in space can shed light on osteoporosis, a condition that affects hundreds of millions of people worldwide—as well as how to keep astronauts safer .

What is the relationship between bone density, osteoporosis and gravity that makes this space research relevant to normal people?

Allen Liu: Osteoporosis causes bones to become weak and brittle as individuals age, causing fractures even with mild strains and falls. There are an estimated 10 million cases in the US with another 43 million showing signs of low bone density.

A weightless environment, or microgravity, can induce physiological changes in bone and presents a unique research environment without the typical mechanical stresses of gravity. It also rapidly changes the way cells grow and function without the use of drugs or genetic engineering.

A cell’s stiffness can tell us its biological age, predicting how its function or susceptibility to chronic disease may decline over time. We are testing the hypothesis that when cells are not pushed back against gravity, this reduction in stiffness makes them susceptible to the same type of changes that we see in osteoporosis. But we also believe we can prevent these health effects by mechanically compressing the cells in a way that mimics gravity.

How will you see cell stiffness in space? What can this tell you about astronauts?

Nadab Wubshet, PhD student in mechanical engineering: We hypothesize that the absence of gravity may cause softening of the cells, which could be behind the bone loss seen in astronauts after long stays on the ISS. Astronauts do resistance exercises on board to create the compression effect that is absent without gravity.

To test the stiffness of cells on the ISS, we use an automated microfluidic device that uses fluids to trap individual cells and slowly increase the pressure on each cell to cause deformation. Fluorescent indicators allow us to see its shape at each pressure level. Our device is also integrated with a system that takes snapshots and videos that allow us to collect data to measure cell stiffness.

How can this benefit human health?

Wubshet: If our hypothesis turns out to be correct, our results will provide great insight into how changes in physical forces such as gravity affect the mechanical characteristics of bone cells – and bone formation. A better understanding of the impact of physical forces such as gravity on bone formation could provide insights into better diagnostics and treatments for people experiencing bone decay.

But applications in space are also important, especially given the growing interest in space exploration that could have astronauts in microgravity for longer periods of time. We hope to develop solutions to preserve bone density for these astronauts.

In the second experiment, you are trying to reduce bone cell damage—what do you hope to learn?

Grace Cai, PhD student in applied physics: The cells we referred to as “bone cells” are osteoblasts, which deposit minerals and proteins to build bone when and where it’s most needed. In our study, we investigate how microgravity affects osteoblast activity.

Cells in microgravity exhibit low cell tension and we can increase cell tension by applying mechanical compression. By placing spherical clusters of human osteoblast cells in zero gravity and applying compression, we can test whether it promotes bone cell growth and maintenance while preventing bone loss.

How will the samples be returned to Earth and how do you see their analysis benefiting future astronauts?

Cai: While the first experiment will be conducted on the ISS, samples for this second experiment will be returned to Earth on SpaceX CRS-26 in January for analysis. Our findings here should shed light on whether compressive spacesuits and clothing could prevent bone loss and improve bone health in astronauts exposed to microgravity conditions. These kinds of technologies could help protect crews traveling to and from the ISS, as well as to other destinations.

In addition to informing osteoporosis research on Earth, we expect our findings will likely be relevant to other age-related diseases and cancers. Cellular engineering and the architectures that cells construct, which are fundamental to our own study, are important in these areas as well.

What are the most interesting things you have learned as a mechanical engineer preparing experiments for space?

Liu: One challenge with working in a microgravity environment is that everything is weightless, so handling the liquid becomes extremely difficult. Everything should be sealed and our cells should be kept in a bag instead of a petri dish. And because space is at a premium on the ISS, each experiment is packed into a small CubeLab container, approximately 6.3″ high, 8.2″ long and 12.3″ wide.

As a researcher, I think we are used to uncertainties, but this is very different. Many things can go wrong with an experiment on Earth, and it makes it even more difficult to do the experiment right in space. We hope the experiments go smoothly and I’m glad we made the flight.

Provided by the University of Michigan

Reference: Experiments to Study Gravity Impact on Bone Cells Head to International Space Station (2022, November 7) Retrieved November 7, 2022 from https://phys.org/news/2022-11-gravity-impact-bone -cells-international .html

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