Space & Innovation

CL TESTING NASA Lung Experiment Looks at How Well Cells Repair

Every breath a person takes inflicts minor damage to the lungs. Results from this NASA study could one day bring a better way to treat lung disease.

We know that microgravity hurts a lot of human systems — the eyes, the bones, the muscles, even the heart. But what does it do to the lungs? Can they function normally in microgravity, or is there a problem that needs to be addressed? Some past astronauts reported minor respiratory problems in orbit. Is it because of microgravity, or something else?

A newly returned investigation from the International Space Station aims to learn more. Specifically, researchers are interested in how well lungs can heal themselves in space. While we take breathing for granted here on Earth, a little-known fact is that every breath a person takes inflicts minor damage to the lungs. Nature can usually repair it quickly, but how well does the process work in microgravity?

The results could one day translate into a better way to treat lung disease. A nasty example is chronic obstructive pulmonary disease (COPD), in which it becomes harder and harder to breathe due to reduced airflow. Star Trek actor Leonard Nimoy (aka Spock) died in 2015 of the disease, which he said was brought on by smoking.

“I’m really interested in how lungs repair themselves. To understand [lung repair], you have to understand how progenitor cells – the stem cells responsible for wound healing – function,” chief investigator Joan Nichols told Seeker.

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Nichols is a professor of internal medicine, microbiology, and immunology at the University of Texas Medical Branch. This was her first space-based experiment. Her co-investigator is medical doctor Joaquin Cortiella, who works at the same institution and advises Nichols on medical applications for the research. Their experiment is called “The Effect of Microgravity on Stem Cell Mediated Recellularization (Lung Tissue).”

Nichols is particularly interested in the role of pneumocytes, which are cells that line lung cavities. Type 1 pneumocytes facilitate gas exchange — “We want to make sure we keep it very healthy,” Nichols remarked — while Type 2 pneumocytes secrete a substance called a surfactant to decrease surface tension. Type 2 cells can replace Type 1 cells as the Type 1 cells naturally die off, but they only do it in low numbers. There’s also another complication: gravity cues the body as to which type of cell is which.

“In space, [the cells] don’t [touch] as much, so it might be bad for astronauts on long-term spaceflight,” Nichols said. “For me, I hope to gain an understanding into how our lungs heal, which maybe would provide me with a plan or therapeutics. In the case of COPD or lost lung function, perhaps we would be able to replace the missing cells.”

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For the experiment, Nichols’ team created 60 tiny human lung scaffold pieces (just 0.5 mm cubed) to support the growth of bioengineered lung tissue — including, specifically, Type 2 cells. The samples were carefully checked for possible contamination before flight. After getting the all-clear, the samples were rocketed to space on a Dragon spacecraft and curated in a science glovebox on the ISS during Expeditions 51 and 52. Then they were brought back to Earth on Sept. 17, also on a Dragon.

Nichols has just started her analysis, but she already sees some differences between the lung tissue samples she grew as a control on Earth and the ones that flew in space. 

“They don’t have the same structures of the little ovular spaces,” she said.

In future months, she’ll examine things such as the amount of surfactant the Type 2 cells produced. Once she has preliminary results, she plans to write another proposal to NASA to try to land another investigation on the space station in a couple of years.

In the distant future, Nichols said it could be useful to grow pure stem cells in microgravity and then transfer them to a scaffold here on Earth, in order to grow an entire lung. This could make it easier to achieve lung transplants for patients. But such a goal, she cautioned, is many years away.

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