Heart health in space

Davide Montebruno

Astronauts face many risks in the line of duty, but the longest lasting impact may be to their heart health. UM researcher Lorrie Kirshenbaum believes that recent breakthroughs in the health impacts of shift work may hold answers for astronauts returning from the International Space Station (ISS).

“Like shift workers, astronauts on board the ISS experience disruptions to the body’s circadian clock, due to the frequent sun rises and sun set every 90 minutes while orbiting the earth, which increases the risk of cardiovascular disease,” says Dr. Lorrie Kirshenbaum, professor physiology and pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences and Director, Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre.

Kirshenbaum and collaborator Dr. Inna Rabinovich-Nikitin funded by the Canadian Space Agency to investigate the effects of circadian disruption risks on cardiovascular health on Earth and faced by astronauts during space flight. Now, in a new collaboration with NASA, their study will expand to include the effects of microgravity on heart cells.

“Our team is uniquely positioned to marry our research in circadian disruptions with the considerable data already collected by NASA in microgravity over decades of space flight to explain impacts on the heart,” says Kirshenbaum. “It's one of the most exciting opportunities we’ve had conducting cardiovascular research.”

Astronauts onboard the international space station see 16 sunrises and sunsets every 90 minutes.

Dr. Lorrie Kirshenbaum

The heart in orbit

On Earth the normal shape of the heart is like a football, but in microgravity during space flight the heart’s shape changes to become more like a soccer ball. Removing the effects of gravity reduces the work the heart has to do to pump, causing blood to shift upward toward the head from the lower body.

During the Gemini and Apollo programs of the 1960s, NASA scientists concluded that these changes to the heart were temporary and had minimal impact, since astronauts aren’t doing strenuous labour. However, astronauts now regularly work in orbit for months at a time resulting in blood vessel remodeling that may have long term effects at the cellular level once back on Earth.

“We believe that interventions that correct circadian mis-alignment in microgravity conditions through metabolism and exercise, could play a key role in mitigating some of the effects of space flight in the same way we are helping shift-workers,” says Kirshenbaum. “If you can figure out the right schedule, what to eat and at what time to exercise, we can reduce these long-term impacts and extend the length of time people can safely be in space. This is important if astronauts are one day going to travel to Mars.”

Exploring microgravity on Earth

Studying the effects of microgravity on Earth is a difficult challenge for Kirshenbaum’s team, who are working to design an experiment to simulate a gravity free environment for living heart muscle cells. Their plan is to build a miniaturized version of the gyroscopes often used when astronauts train for space flight, called a random position machine. It will let them study living heart cells under conditions similar to space.

“A lot of this technology we need for this study doesn't exist yet,” says Kirshenbaum. “We're learning from NASA and our collaboration will draw on their expertise to build our own test equipment at UM in Winnipeg.”

Understanding how to minimize the risk of cardiovascular disease for astronauts also has implications here on Earth, to improve understanding of how heart cells are affected by circadian disruption. For example, Kirshenbaum notes in cardiac patients with heart failure, the heart changes shape to look like a “soccer ball” similar to what happens in space.

This may one day lead to new therapies and treatment strategies for mitigating cardiovascular disease on Earth.

“By expanding our understanding of health in extreme environments, Drs. Kirshenbaum and Rabinovich-Nikitin are informing the future of cardiovascular treatment,” says Dr. Mario Pinto, Vice-President Research and International. “This international partnership exemplifies the UM strategic research priority for strengthening health and well-being around the world -- and beyond.”