The SpaceX Falcon 9 rocket carrying the Dragon capsule lifts off NASA’s Kennedy Space Center on June 5, 2023, on the company’s 28th Commercial Resupply Services mission for the agency to the International Space Station. (Credit: SpaceX)

Approximately 10 percent of babies in the U.S. are born prematurely, which puts them at risk for developing respiratory distress syndrome (RDS). Babies with RDS struggle to breathe and keep their airways open because they lack pulmonary surfactants — foamy substances that help inflate the tiny air sacs in their lungs. To open up their airways, infants affected by RDS are often successfully treated with surfactant replacement therapy, which uses liquid plugs to deliver therapeutic drugs from the airway into the lungs. However, for adults who face similar breathing issues, this type of therapy is not as effective. To better understand why, researchers from the University of California, Santa Barbara (UCSB) are turning to the microgravity environment  of the International Space Station (ISS)  National Laboratory.

In utero, babies depend on their mothers for survival as their bodily systems develop and mature. The lungs begin producing surfactants during the third trimester. So, the earlier a baby is born, the more likely they are to lack the necessary surfactants needed to breathe. But babies are not the only ones affected by respiratory distress disorders. Adults can face acute respiratory distress syndrome when the smaller air sacs in a lung fail to inflate, making it harder to breathe.

“Surfactant replacement therapy has had a lot of success in premature babies. It’s really extending that therapy to adults that has not been quite as successful, and we’d like to understand why,” says Emilie Dressaire, an assistant professor at the UCSB College of Engineering . “Our hope is that if we better understand how the mucus is affecting the transport of the plugs, then we can modify how to approach treatment and get the most out of it.”

Naturally occurring fluids in the body, like mucus, can impact the success of surfactant replacement therapy, especially in adults. Dressaire is hoping that the microgravity conditions of the space station will help her team better understand how the mucus lining of the airway system affects the transport of liquid plugs, such as surfactants, through the airway. As such, her team is launching an investigation on SpaceX’s upcoming 29th Commercial Resupply Services (CRS) mission to study the dynamics of fluids as they move through gel-coated tubes, which mimic the mucosal lining in the human lung. This research could lead to improved drug delivery, and ultimately, a higher treatment success rate.

Dressaire says her team wants to eliminate the effects of gravity to better understand the effects of mucus on drug delivery. “Is this treatment less effective in adults because of the complexity of the lungs — there are more branches and more pathways the medication has to go through in adult lungs — or is it because of mucus?” she says.

Adults have bigger bodies and larger lungs, and by performing the experiment in microgravity, the team can nearly eliminate the effects of gravity—which, along with surface tension, helps to drive the transport of liquid plugs through the airways of patients on Earth. At smaller scales (for example, in the tiny air passages deep in the lungs) the effects of surface tension cannot be separated from the effects of gravity, making it difficult to discern the actions of the individual forces.

By sending the project to space, the team can observe the isolated effects of surface tension on liquid plug transport through a gel — an opportunity that would not be feasible in a laboratory on Earth. The gel is used as a soft layer that simulates mucus in the human body. The team is using multiple tubes and gel combinations to determine how the amount of gel affects how liquid flows through the tubes.

“What this project is trying to figure out is how the mucus lining is affecting the transportation of this medication,” Dressaire says. “Is it slowing the medication down? Is it trapping some of it along the way so it’s not reaching the lungs? This is what we hope to determine.”

The SpaceX CRS-29 mission, scheduled to launch from Kennedy Space Center on November 5 at 10:01 p.m. EST, includes more than 15 ISS National Lab-sponsored payloads.

To learn more about all ISS National Lab-sponsored research on this mission, visit the ISS launch page .