“Prepare for a human presence at Mars.”
A simple phrase, but one that packs a galactic punch — especially for the self-professed space nerds among us.
The language is part of a plan released last year by the Mars Exploration Program at NASA. The plan outlines a slew of goals for the Mars Exploration Program over the next 20 years, including a mission to better understand the effects of Mars’ climate on NASA astronauts. With a grant from NASA, a project in the School of Education’s Department of Kinesiology is helping answer that question.
Postdoctoral fellow Kaylin Didier and professor of kinesiology Bill Schrage are leading the project, which aims to increase understanding of how radiation — which exists in high levels on the journey to Mars — affects human immune cells. In particular, they’re testing how immune cells in women respond differently to radiation than immune cells in men.
“Because we are going to send women to Mars, we thought there was an opportunity to answer a sex difference question,” Didier explains.
According to NASA, the number of female astronauts has increased sharply over the past two decades. In 2004, only 18% of the astronauts at NASA were women. By 2021, that number increased to 42%.
“It’s exciting to be a part of something that will benefit all astronauts as they prepare for the journey to Mars, and to support their long-term health when they return home,” Didier says.
During space travel, astronauts are exposed to multiple types of radiation that Earth’s atmosphere and magnetic field provide protection against. Radiation exposure can have numerous physical effects, from nausea and burns to cell damage and an increased likelihood of cancer. Helping NASA understand how different cells respond to radiation could help the agency build better equipment, like radiation shields, as well as potential medical interventions before, during, and after traveling to Mars.
To examine their specific piece of the puzzle, Didier and Schrage perform what Schrage jokingly calls “really nerdy, highly-controlled science.”
Basically, the team takes immune cells — known to a general audience as white blood cells — and incubates them in a series of small flasks. They stack the flasks under the beam of a radiation machine, also known as a linear accelerator, and expose them to brief, low amounts of high-energy radiation. For this project, Didier and Schrage used a rare accelerator that delivers a highly precise form of radiation using protons. In the clinical world, this form of radiation is called “proton therapy.”
“Utilizing ionizing proton radiation was important to us, because space radiation is predominantly made up of protons,” Didier explains.
About 90% of deep space radiation is high-energy protons, and the linear accelerator Didier and Schrage were able to access — a machine operated by Northwestern Medicine in Warrenville, Ill. — delivers an exposure similar to the protons astronauts will experience while traveling to Mars.
Sometimes, the incubated cells receive a radiation dose for less than one second. Other times, the dosage lasts up to 45 seconds. In all, Didier made two trips to Illinois for data collection, called “radiation bouts,” using cells from 15 men and 15 women.
In January, Didier presented preliminary results from a small sample of the study at NASA offices in Houston. Didier’s full analysis is due at NASA this fall. She also expects to publish multiple papers on the research in peer-reviewed journals.
Didier says the relatively small amount of radiation exposure involved in this study means there is a great deal more to explore in future analyses.
“We definitely have more questions about doses of radiation,” she says. “We have one dose of radiation in this experiment, and these astronauts are going to experience continuous dosing in space.”
She says there are also opportunities to examine different types of immune cells in future experiments. This project used classical monocytes, but there are also B cells, T cells, and natural killer cells, among others.
Of course, there is also the potential to apply the research to a much larger population than NASA astronauts.
Roughly a decade ago, Didier made her first master’s-level research presentation. That presentation was about the effects of radiation on cancer patients.
“In some ways, my research interest hasn’t gone far — it’s stayed in the radiation realm,” she says.
Didier says it’s clear her work for NASA could also benefit the millions of people who undergo radiation as part of cancer treatment.
“The discoveries we make while preparing for the mission to Mars can also provide solutions to ground-based problems,” she says. “While I love nerding out about space, I also really appreciate that I’m looking into something that affects a lot of people undergoing treatment for different diseases.”
Down to Earth: Schrage lab applies NASA study questions to multiple projects
Though professor Bill Schrage wasn’t a stranger to NASA research — he conducted a NASA-funded study on the impacts of microgravity on rats in the late ’90s and early ’00s — it wasn’t his experience with the agency that led Kaylin Didier to believe his lab would be a good fit for her NASA-funded project.
Instead, Didier knew Schrage’s experience studying the immune system and effects of sex differences on physical health would be broadly beneficial.
“Working with Dr. Schrage provided the opportunity to expand my knowledge base and skill set,” Didier says.
In general, Schrage’s lab has focused in recent years on studies of blood flow and brain health, as well as cardiovascular disease, obesity, and pre-diabetes. The latter conditions are often linked with inflammation, an immune response.
The biggest ongoing project in Schrage’s lab is a five-year study funded by the National Institutes of Health examining how men and women regulate brain blood flow differently. The analysis could help increase understanding of neurological conditions like Alzheimer’s disease and dementia.
“There are all kinds of sex differences with the onset of Alzheimer’s,” Schrage explains. “Most people attribute those differences to the presence and levels of sex hormones. We are testing how sex hormones work with the immune system to regulate inflammation.”
For the study, Schrage and his team are working with more than 100 healthy young men and women to measure their brain blood flow. The researchers will manipulate some participants’ sex hormone levels for short periods of time to gauge how the presence of those hormones affects blood circulation in the brain.
Another study in the lab aims to learn more about how pre-diabetes affects brain blood flow, including the potential for pre-diabetes to cancel out the cardiovascular health benefits of estrogen and increase risk of neurological disease.
Broadly, Schrage says he always aims to keep the collaborative, incremental progress of the larger scientific research community in mind.
“From a research perspective, we’re not trying to cure a specific disease,” he says. “The big idea is to better understand how these conditions are related.”