After 22 days, the heart cells were returned to Earth — and they were still beating. The implications of this experiment mark a significant step toward helping heart patients on Earth in the future.
The results of this experiment were the subject of a virtual panel discussion Tuesday that CNN obtained exclusive access to — panel members included NASA astronaut Jessica Meir and researchers from Emory University and Children’s Healthcare of Atlanta. They were joined by Brody Parker, a former heart patient who will soon celebrate his 11th birthday and his two-year heart transplant anniversary.
Two years ago, Parker said he was “an average 8-year-old boy” who enjoyed playing soccer and spending time with his friends. In May 2019, he started feeling tired all of the time and stopped wanting to do the things he enjoyed.
On June 1, 2019, Parker said he didn’t feel well. He ended up taking his first helicopter ride to Children’s Egleston Hospital in Atlanta. He had dilated cardiomyopathy, which causes difficulty in the heart’s left ventricle’s ability to pump blood. Parker spent all of June and July in the hospital and received a transplant.
Since his procedure, Parker has been able to return to a normal life of playing soccer and baseball with his friends, and he’s getting straight A’s in school.
Future pediatric heart patients could benefit from researching beating heart cells in space because they could begin a new phase of personalized medicine.
The beating heart cells, called cardiomyocytes, featured in the experiment were grown from pluripotent stem cells. These master cells are ideal because they can be turned into multiple cell types. In this case, pluripotent stem cells could become healthy heart cells for a patient with heart disease.
Stem cell therapies to repair damaged heart cells require at least 1 billion cells per patient. When her experiment using simulated microgravity on Earth showed promising steps toward quickly and safely producing cardiomyocytes, Xu saw space as the ultimate proving ground.
The heart cells were cryopreserved, or frozen, and then thawed once they reached the station. This allowed the cell cultures to grow in space for 21 days. Meir oversaw the experiment while it was on the space station.
“Doing science on the International Space Station is absolutely a dream come true for a scientist turned astronaut like me,” Meir said.
“Imagine a place where every person and everything is living in a totally different environment than here on Earth,” she said. “This one-of-a-kind place is what makes doing research on the International Space Station so incredibly special. We can test things that we can’t do anywhere on Earth.”
When these live cells returned to Earth, Xu and her colleagues discovered that the stem cells grow faster in zero gravity. This means that more cells can be grown at a faster rate.
This rapid ability to grow cardiomyocytes could generate a multitude of healthy heart cells for children and adults with various heart diseases. But they could also be used to understand heart health and the aging process in a broader context.
Clinically, these beating heart cells could help kids and teenagers like Parker that have damaged heart valves receive replacement valves grown from their own stem cells.
“To really try to understand the heart, we need to look at the cells,” Maher said to Parker. “In her lab, (Xu) can grow anybody’s heart cells from a little piece of skin, or a little bit of blood. And the amazing part is those cells are exactly the same as the heart cells in our body. So then we can start to investigate what the cells are doing. We can look at the genetics and we can try new medications.”
It opens up the possibility for personalized medicine and could allow for the testing of medication or treatments on cells, rather than the patient.
There is a high standard for the stem cells to be pure. Residual stem cells that don’t turn into heart cells can actually cause tumors, according to previous research by Xu. More mature cells stand a better chance of becoming pure heart cells.
During her ground-based experiment simulating a lack of gravity, Xu found that the cells were more mature and even expressed survival genes that could ensure cell survival. Overall, these factors would allow the cells to connect with the heart tissue better and cause less issues, Xu said.
“This type of work to be able to really learn how to make cells grow better has the potential to increase the chance that that will happen someday,” Maher said. “It’s not a reality yet, but there’s a lot of work being done on seeing how we can use these types of stem cells to make the heart stronger and better in the future.”