Getting your
Trinity Audioplayer ready...Researchers from UC San Diego and Stanford University conducted tests on small gelatinous sea creatures for insights on aging and cellular rejuvenation. What they found might have some bearing on humans.
Sea squirts are the subject of a new study published last month in the scientific journal * PNAS*. They share more genetic material with humans than you might think.
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“If you want to study the stem cell and differentiation, we can’t study in humans that well because we can’t do experiments in humans,” said Debashis Sahoo, an associate professor of pediatrics in the UC San Diego School of Medicine and a co-author of the study. “We can’t make genetic manipulations and study how and what happens.”
Enter sea squirts.
The spineless creatures share about 70% of the genetic material humans have, making them “the legacy of a common ancestor from roughly 500 million years ago,” according to a statement from UCSD and Stanford.
Sea squirts are considered especially useful in questions about human immune systems and stem cells. Sea squirts are able to rebuild all of their body tissue in roughly a week.
“You want to make some connection to vertebrates,” said Sahoo, who also is an associate professor of computer science at UCSD. “So these sea squirts are right in the intersection of invertebrates and vertebrates. It’s basically a way to connect how vertebrate systems emerged.”
In the study, scientists introduced sea squirts to a brief series of electrical pulses. The results were dramatic, long-lasting health improvements that have the potential to expand their lifespans, according to the researchers.
The work began in 2020 when Stanford stem cell scientist Jos Domen, a co-senior author of the study, used a pacemaker — commonly used to treat abnormal heart rhythms — to boost the pace of the creatures’ heart.
Of the sea squirts that received the treatment, 75% were alive and healthy a year later. Of their untreated peers, only 20% survived.
“In the same way electricity can help reboot the heart into a regular sinus rhythm, we found that electricity triggers a reboot in sea squirts at the gene expression level,” Sahoo said. “Gene activity reduces, but then comes back even stronger, similar to what happens in humans after a hard workout.”
The findings, Sahoo said, tie into his previous research on exercise and its effects on the human body.
“We saw that in humans, when you do acute exercise, [in which] somebody who has not done exercise for a while did one hour of strenuous exercise, their macrophages [cells in the immune system that destroy pathogens] will be reactive,” Sahoo said. “[For] somebody who is doing exercise for a long time, we saw that their macrophages become tolerant over time.
“We assumed these electrical pulses [for the sea squirt] would be equivalent to doing exercise.”
Similar treatments in humans are not imminent. But scientists say they’re optimistic that the findings can yield helpful insights.
“An obvious question is whether this can be applied to humans,” Domen said. “This would take a different form than the sea squirt exeriments and would focus on specific cell populations, like blood stem cells that can be stimulated in a similar way.”
For Sahoo, it raises the question of what happens in our bodies when we exercise and how we can improve our performance based on that knowledge. “We want to optimize ourselves in various ways,” he said. “We talk about athletes, soldiers or any other [people in] extreme situations. We want to get to the extreme.
“This also connects to how aging destroys some of the system and what kind of damage is accumulated over aging that we could maybe fix. Maybe we can’t make it reverse … but at least if you can fix it in some ways, it can affect diseases.” ♦