If manned missions are to go to Mars there has to be some way to protect the human body against the effects of space travel. As part of meeting this challenge, NASA is conducting experiments aboard the International Space Station (ISS) aimed at learning how the lungs repair themselves in zero gravity. The Effect of Microgravity on Stem Cell Mediated Recellularization (Lung Tissue) investigation promises to not only keep astronauts healthy, but could provide a new source of artificial transplant organs.
According to NASA, there's been a lot of work done on the effects of space on the cardiovascular system, eyes, bones, and muscles, but the lungs have been overlooked except in the most general of studies. This is unfortunate because the lungs are not only a vital organ linked with the heart and blood vessels, they are also very much adapted to working in gravity.
Without gravity, the lungs undergo all manner of changes. Fluids that would normally drain away collect in unpredictable manners, ventilation changes, and blood flow and the exchange of gases are also affected. In addition, though very durable, lungs are damaged every time a person breathes and are only able to keep functioning by constantly cleansing and repairing themselves. Just look at the overwhelmed lungs of someone raised in the polluted air of the city compared to someone living in the clean air of the country and the lesson is obvious, even to the untutored eye.
To help protect space travelers, the NASA lung study is looking at how lungs are able to regrow themselves by sending sections of lung tissue to the ISS that have been treated to remove all the living cells, leaving behind a lifeless scaffold of collagen. Stem cells are introduced into this scaffold, called the Microphysiological Human Organ Culture Model (MHOC), where they evolve into complete, specialized lung cells. Examining how these cells develop will help scientists to better understand the problems lungs face in weightlessness and how to counteract them.
"We need to understand how lungs heal over long-term spaceflight," says Joan Nichols, principal investigator for the investigation and professor of internal medicine, microbiology and immunology at the University of Texas Medical Branch (UTMB). "If they don't heal properly, we might be able to come up with a microparticle therapeutic treatment that you breathe through an inhaler that would limit the damage that we're seeing or enhance the cells to do what you need them to do."
One of the benefits of the zero gravity study is that stem cells grow more readily in weightless conditions while remaining pure and immature longer. This raises the possibility of using space stations as breeding grounds for human stem cells that could be returned to Earth and installed in a large scaffold to create a complete lung suitable for transplant.
"It's hard, on Earth, for me to grow enough of these cells and expand them out because they start maturing immediately," says Nichols. "If I can grow more in space, then I might be able to take a sample, isolate those cells that I work with, grow them to high numbers and then come back and make a lung for replacement either using a whole natural lung scaffold or develop a bio printing technique to print one that fits perfectly."
NASA says that tissue samples from the study were returned to Earth on September 17 aboard the SpaceX Dragon cargo ship and are currently being studied at the UTMB.
The video below outlines the investigation.