Researchers from UC San Diego and Stanford University have discovered that brief electrical pulses can dramatically improve the health and extend the lifespan of sea squirts, small gelatinous marine creatures. The findings, published last month in the journal PNAS, may offer valuable insights into aging and cellular rejuvenation in humans.
Sea squirts are uniquely positioned in the evolutionary tree, straddling the line between invertebrates and vertebrates. This makes them ideal for studying stem cells and immune system development, as experiments on humans are often impractical or unethical.
"If you want to study stem cells and differentiation, we can't study that well in humans because we can't do experiments on them," said Debashis Sahoo, an associate professor of pediatrics at UC San Diego School of Medicine and a co-author of the study. "We can't make genetic manipulations and study what happens."
The study began in 2020 when Stanford stem cell scientist Jos Domen, a co-senior author, used a pacemaker to boost the heart rate of sea squirts. The creatures are known for their remarkable ability to regenerate all of their body tissue in about a week.
After a brief series of electrical pulses, the sea squirts showed dramatic and long-lasting health improvements, effectively expanding their lifespans.
A year after treatment, 75% of the treated sea squirts were alive and healthy, compared to only 20% of their untreated peers. "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 explained.
"Gene activity reduces, but then comes back even stronger, similar to what happens in humans after a hard workout."
The findings tie into Sahoo's previous research on exercise. He noted that acute exercise in humans makes macrophages—immune cells that destroy pathogens—reactive, while long-term exercise makes them tolerant.
"We assumed these electrical pulses for the sea squirt would be equivalent to doing exercise," he said.
While similar treatments for humans are not imminent, scientists are optimistic. "An obvious question is whether this can be applied to humans," Domen said.
"This would take a different form than the sea squirt experiments and would focus on specific cell populations, like blood stem cells that can be stimulated in a similar way."
Sahoo added that the research raises questions about how exercise affects the body and how performance can be optimized. "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." He also noted that the study connects to how aging damages systems and how accumulated damage might be repaired, potentially affecting diseases.