Johns Hopkins Medicine researchers collaborated with NASA to send human heart “tissue-on-a-chip” specimens into space in March aboard SpaceX CRS-27, a resupply mission to the International Space Station. The project is designed to monitor the tissue for changes in heart muscle cells’ mitochondria and ability to contract in low-gravity conditions.
Astronauts on board during the mission also introduced three FDA-approved medicines to the samples in efforts to prevent heart cell changes known or suspected to occur in those undertaking long-duration spaceflights.
“It’s possible that what we learn from these experiments in space could also inform how we treat age-related cardiac problems,” says biomedical engineer Deok-Ho Kim. That’s because many heart cellular changes already detected in space explorers mimic changes linked to heart muscle aging in general.
To develop the microengineered human heart tissue-on-a-chip, researchers begin with human induced pluripotent stem cells grown in the laboratory. Such cells are able to develop into nearly any type of cell, and are coaxed biologically to develop into beating human cardiomyocytes, the muscle cells that make hearts contract.
Groups of cardiomyocytes form tissue that can be strung between two posts, one flexible and one stiff. The flexible post has an embedded magnet and, when placed over sensors, allows for collection of information on tissue contraction. The chamber enclosing the tissue is sealed so that liquid media feeding the tissue doesn’t float away in space. These tissue chambers are then loaded into so-called plate habitats with the magnetic sensors located beneath the tissue.
Kim, his previous postdoctoral researcher Jonathan Tsui, and his doctoral student Devin Mair previously sent heart tissue into space in March 2020. Those experiments showed that microgravity in space changed the cells’ mitochondria and the tissues’ ability to contract.
In the new experiments, the scientists focused on the proteins activated during tissue inflammation and mitochondrial dysfunction. The astronauts aboard the space station also tested whether any of three medicines can stave off the problems anticipated in space-bound heart cells.
Astronauts and researchers completed their experiments on the International Space Station in April. The heart tissue samples are being processed and analyzed for further study by Johns Hopkins researchers in laboratories at Johns Hopkins All Children’s Hospital in St. Petersburg, Florida.
