A tiny, six-legged critter that suspends all biological activity when the going gets tough may hold answers to a better way to cryopreserve human eggs, researchers say.

Tardigrades, also called water bears, can survive Himalayan heights or ocean depths as long as they have moisture.

When they dont, they produce a sugar, trehalose, slowly dehydrate and essentially cease functioning until the rain comes, says Dr. Ali Eroglu, reproductive biologist and cryobiologist at the Medical College of Georgia.

Tardigrades are not alone in their amazing ability to outlast adverse conditions. A type of brine shrimp, often called a sea monkey, comes back to life with water. The Bakers yeast Dr. Eroglu uses when he bakes bread with his children does as well. Similarly arctic wood frogs use the sugar, glucose, to tolerate frigid temperatures until the summer thaw.

While humans dont naturally produce trehalose, researchers think they can use it to safely preserve human eggs and those of endangered species giving better options to young women facing cancer therapies that may leave them infertile and others who simply want to delay reproduction.

"Our hypothesis is when we introduce sugars into cells and into oocytes, we can protect them against freezing-associated stresses," says Dr. Eroglu, who received a $1.2 million grant from the National Institute of Child Health and Human Development to continue pursuing his hypothesis. "We also hypothesized if we used trehalose, we also could use conventional cryoprotectants, which can be toxic, in lower concentrations to minimize their toxicity while maximizing overall protection."

Pilot data show it works like a charm, at least in mouse eggs. Researchers injected eggs with trehalose, cooled them to liquid nitrogen temperature, thawed them and exposed them to sperm. They got healthy babies at a similar rate to unfrozen controls.

"We were very excited," says Dr. Ero
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Contact: Toni Baker
tbaker@mcg.edu
706-721-4421
Medical College of Georgia
18-Dec-2006