Across the tree of life, there are many organisms that can essentially cheat time by decelerating their biology. Chief among them is the tardigrade, a creature no bigger than a speck of sand that can survive severe temperatures, outer space and all sorts of apocalyptic scenarios.
A team at Harvard Medical School is studying tardigrades in hopes of finding medical treatments that halt tissue damage. They are drawing inspiration from special proteins suspected to help tardigrades achieve suspended animation. They aim to synthesize a version of these proteins that can enter human cells and pause processes leading to cell death.
“When somebody is wounded, there’s a window of time they have to get to a medic or a hospital. So our overarching goal is: how do you prolong that time?” said Pamela Silver, a professor of systems biology.
Also known as a water bear or moss piglet, a tardigrade looks like a croissant with eight pudgy legs under a microscope. They live just about anywhere there’s water, from mundane parking lots to the most extreme environments on Earth: deep-sea trenches, hot springs, the peaks of the Himalayas and the depths of Antarctic ice.
The invertebrates enter a dormant state called anhydrobiosis, in which they curl into a desiccated ball called a tun and lower their metabolism to 0.01 percent of normal. They can stay as tuns for decades and resume business after being rehydrated.
In 2017, scientists discovered proteins, called tardigrade-specific intrinsically disordered proteins, that might help put the creatures’ cells in a protective state during anhydrobiosis. It’s unclear exactly how these proteins work, said Roger Larken Chang, who directs Silver’s lab. Preliminary research suggests that they might form a biological glass that immobilizes everything in a cell during periods of stress.
To lay the groundwork for engineering a synthetic protein, Silver and Chang teamed up with Debora Marks, a Harvard computational biologist whose lab has created an algorithm that can search millions of protein sequences for recurring patterns.
The team was awarded a contract in December from the Defense Advanced Research Projects Agency (DARPA), the federal agency that funds the development of technologies of interest to the U.S. military. DARPA is interested in protein-based therapies to stall bleeding and tissue death in traumatic injuries, Silver said.
There are other potential applications, including refrigeration-free preservation of protein-based drugs, eggs for in vitro fertilization or organs for transplantation, Chang said. In the future, it could even pave the way for preserving live bodies for space travel or emergency scenarios.
“There are many things that sound crazy that organisms, like tardigrades, actually do,” Silver said. “That’s the surprising thing. There’s a lot out there in nature.”