What has two heads, no heart and busted through the stratosphere? The humble flatworm.
Tufts University scientists studying the regenerative medicine process used two sets of planarian flatworms — one on Earth and one aboard the International Space Station — to see what changes when an organism is in outer space.
"As humans transition toward becoming a space-faring species, it is important that we deduce the impact of space flight on regenerative health for the sake of medicine and the future of space laboratory research," Junji Morokuma, research associate in Levin's lab and first author on the paper, said in a press release.
The experiment used flatworms because of their ability to regenerate parts of their body in the event of amputation. The researchers amputated some of the worms and left others whole and sealed them in half-air half-water tubes on Earth, while sending an identical set of worms into space. The latter spent five weeks on the SpaceX Dragon spacecraft.
Scientists examined the squirmy subjects upon their return to Earth to see how they would fare after they were reintroduced to gravity. Some of the space worms, unlike their counterparts on Earth, underwent spontaneous fission. That is when the body randomly divides into two or more of itself. Of the 15 space-traveling worms, one regenerated into a double-headed worm. According to the study, this hasn't been observed in over 18 years.
"Seeing a two-headed flatworm was pretty remarkable," Michael Levin, a Tufts University biologist who co-authored the paper, told Smithsonian. Additionally, when the scientists cut off the heads, they both regenerated. "These changes appear to be permanent, or at least long-lasting," Levin said.
According to Smithsonian, when the astro-worms returned to Earth, they were curled up and paralyzed. They uncurled and returned to normal movement within two hours. This was not observed in the control group. Another finding was that the worms on Earth spent more time in the dark than the space worms.
It's worth noting that there were a number of limitations to the experiment, including temperatures, the stress of space flight as well as amputation on Earth. For more accurate findings, astronauts would amputate the worms in space.