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San Antonio Researchers' Twin Study Adds To 'Dr. McCoy's Tool Chest'

Identical twin astronauts Mark and Scott Kelly.

Scientists from UT Health San Antonio are among the select few who have expanded their research to include the final frontier.

Dr. Kumar Sharma and biologist Manjula Darshi from UT Health San Antonio’s Center for Renal Precision Medicine, along with Brinda Rana from the University of California, San Diego, worked on the NASA twins study, in which identical twins Mark and Scott Kelly submitted themselves to be studied by ten research teams during the year Scott Kelly was living at the International Space Station and Mark Kelly remained earthbound.

The Kelly brothers are now both retired astronauts. They’re the only known siblings to have both traveled in space, and both have been space shuttle pilots.

Dr. Sharma said twin studies are extremely valuable to researchers.


"They have the identical genome when they're born so anything that's different that occurs to them is probably not based on their initial genetic structure," Sharma said.


Sharma and Darshi wanted to know how space travel might change the function of our cells’ mitochondria.

Credit Will Sansom / UT Health San Antonio
UT Health San Antonio
Dr. Kumar Sharma and biologist Manjula Darshi from UT Health San Antonio’s Center for Renal Precision Medicine led one of ten research teams that worked on the NASA Twins Study.

"Mitochondria is the powerhouse of the cell and where you get all the energy to do the functions of each organ,” Sharma said. “So if you're having a reduction in mitochondrial function, your cells aren't going to be at peak efficiency."

But first, they had to figure out how to study someone who was living in low-Earth orbit, and Sharma said that meant answering a series of questions.

"How do you collect urine? How do you get it separated in space? How do you bring it back down to earth? Get the right tubes? Get the right collection procedures, then bring it back down for analysis?"

Credit Manjula Darshi / UT Health San Antonio
UT Health San Antonio

  In the end, the samples came back to Earth in resupply rockets and once in a SpaceXunmanned space capsule, that, once released from the space station, plunged into the Pacific Ocean.

"Absolutely that's the way they sent samples back,” Sharma said, “So those are the samples we ended up getting then doing the analysis."

They specifically analyzed the Kelly's metabolites, which are the small molecules that are the result of cell energy production. Darshi says they noted some differences in the twins’ results.

"One one metabolite that came up specifically was lactate,” Darshi said. “Lactate levels increased in space."

Elevated lactate is one of the ways doctors can determine if your mitochondria function properly. On Earth, your lactate levels can change with increased exercise, low oxygen, stress and inflammation. The good news is when Scott Kelly came back to Earth, his lactate levels stabilized.

"So we are still trying to understand,” Darshi said, “does it mean something, and what are the causes?"

Here on Earth, Sharma is a nephrologist -- an expert on kidney disease -- and he said figuring out why Kelly’s lactate rose might not only help astronauts with their eyes on Mars but also the rest of us.

"We know that mitochondrial function is really the key to protecting organs, whether it's neurologic systems, the brain, the kidneys, the heart, the liver,” Sharma said. “So anything that we learn in protecting the astronauts for their mitochondria should easily be translated to earthlings, as well."

Sharma and Darshi were thrilled that their UT Health San Antonio team was chosen to work on this study.

"Personally, I'm a big Star Trek fan, so this is my little contribution to Dr. McCoy's tool chest," Sharma said.

Added Darshi, "This is definitely one of the great experiences I’ve ever had.”

The results of the NASA twins study were published in the journal Science on April 12.

Bonnie Petrie can be reached at Bonnie@TPR.org and on Twitter at @kbonniepetrie.