Sunday, April 01, 2001 Long-lived organism may hold secret to preserving human tissue

[fair use, for educational and research purposes only] http://www.roanoke.com/roatimes/news/story109738.html

Unlocking preservation's cell

A Virginia Tech team is researching genetic survival methods that may someday dramatically change blood transfusions and organ transplants.

By KEVIN MILLER The Roanoke Times

It's been called the coldest and driest place on Earth, an environment so hostile to life that it bears closer resemblance to Mars than to anywhere else on this planet.

Wind whips through Antarctica's Dry Valleys from the polar ice cap at 100 mph, keeping the air temperature at minus 70 degrees Celsius - below the threshold for nearly all life. Even snow and ice quickly evaporate into the ultra-dry atmosphere, giving the landscape a rocky appearance that defies common perceptions of the icy continent.

Yet burrowed inside the Dry Valleys' rocks is an organism that could one day help save a child in need of a new kidney or a soldier badly wounded on a remote battlefield.

Known in scientific circles as Nostoc commune, the organism has the unique ability to survive near-total dehydration for hundreds of years and, upon rewetting, resume normal life functions as if waking from a cat nap. If those abilities could somehow be transferred to human cells, it could revolutionize blood transfusions and tissue or organ transplantations.

Two Virginia Tech researchers and a team of scientists are busy unlocking the secret of nostoc's amazing resiliency under stress and genetically engineering those traits into human cells.

Bolstered by initial successes, Tech professors Malcolm Potts and Richard Helm have received a $2.6 million grant from the U.S. Department of Defense to continue their research into a technology they believe could forever change the hospital operating room.

Nostoc can be found in back yards and throughout the limestone-rich hills of Southwest Virginia, but its specialty is surviving in places where virtually no other life can exist: Antarctica, the 200-degree hot springs of Yellowstone National Park, even blistering sun-baked summertime rooftops of downtown Blacksburg.

Some of Antarctica's nostoc are estimated to be more than 15,000 years old, meaning they've been alive since the end of the last ice age. But during a typical year, the organisms only live for 500 to 600 hours, if you define life as being biologically active. The rest of the time, the nostoc are in a state of suspended animation: almost entirely dried without a single measurable life function.

Add water, however, and the strands of dehydrated nostoc, which resemble crispy bacon rinds, immediately awaken from their lifeless slumber to become a breathing, photosynthesizing mass of slime. Scientists have revived nostoc samples that have been dried since the 1600s, Potts said.

Most living cells cannot survive total dehydration, called desiccation . Cell walls eventually crack without adequate moisture to protect them, and the cell's insides leak out into their environment.

But what if human blood and tissue cells could be genetically engineered to mimic nostoc's desiccation-resistant properties?

Whole blood and platelets currently have a shelf life of about two weeks, and only then if kept refrigerated. But if blood could be dehydrated it could be kept for months or longer and easily transported to sites of natural disaster or remote battlefields. Likewise, skin tissue used for grafting or even organs could be air-dried and safely stored for extended periods of time, eliminating the need to airlift "live" organs or tissue in coolers.

Another possible application of the technology, Potts explained, is for pharmaceuticals that spoil or are sensitive to temperature. "If you want to get some vaccine up to the top of the Amazon, you can't send a refrigerator," Potts said. And desiccated blood or tissues would solve a major hurdle to long-term space travel.

The military is also interested in developing protein-based biosensors that would alert humans to the presence of toxins, such as those produced in biological weapons. Such biosensors would have to be able to survive in the deserts of Africa and the Middle East as well as extremely cold conditions.

While bags of dried blood and a dehydrated organ bank sound a lot like a scene from "Star Wars," Helm and Potts have already proved that the technology has promise. Several months ago, the team successfully revived human kidney cells that had been air-dried for eight days. The team has dehydrated and revived mouse cells as well.

"At this moment, we are really drying down cells for a short time because we want to see how they are coming back," Helm said.

"If you had said five years ago that you could dry down human cells, we would have said you were crazy because nobody had tried," Potts said. "But now we did it and we have proof of concept."

The next step is to fine-tune the process so that the cells do not lose any of their potential during desiccation, after which Helm and Potts will attempt to dry human tissue and then possibly organs. Ultimately, the duo hopes to desiccate embryonic stem cells, which can be "programmed" to become virtually anything in the body, from new bone or the brain to tissue and nerve cells. Stem cell-based therapies are widely considered to be one of the most promising treatments for countless disorders and injuries.

Standing in one of their several laboratories, Helm and Potts are surrounded by beakers of swirling liquids and scientific equipment. In a drawer below the beakers, several dozen plastic canisters contain samples of dried nostoc collected from throughout the world. A slightly altered household refrigerator contains foil-wrapped clumps of nostoc that Potts picked up on recent trip to a Bahamian lagoon with particularly high salt and radiation levels.

Potts, who has been studying nostoc and other cyanobacterium for more than 20 years, does most of the traveling while Helm, a specialist in plant cell walls, stays in Blacksburg with the dozen-plus staff assisting them in their research. Helm and Potts also receive assistance from several researchers at Louisiana State University; University of California, Davis; and Invitrogen, a Maryland-based biotech company.

The first step after a sample is collected is to separate the pure nostoc from other materials and organisms. The pure nostoc is grown in the laboratory, broken down into different components and then studied.

Potts and Helm have been able to isolate the genes in nostoc that enables it to survive dehydration. Those genes are then introduced into human cells in the hope that the human cells will incorporate the new DNA into their genetic code.

In order to prevent the cell walls from cracking, a naturally occurring substance called glycan is added to the mixture, which acts as the cell's "woolly overcoat" during the dehydration process.

The cells are then dried in an air-tight, temperature-controlled box that resembles a large, clear-plastic microwave oven. After waiting a specified time, the researchers then add water and watch to see if the cells begin to breathe and divide once again.

"The best analogy I can give is it's like going around the house and turning the lights on one by one," Potts said to describe the rehydration process.

There is also work being done on freeze-drying human cells, but Helm, Potts and their team members are the only people researching the air-drying technology. The reason, Potts explained, "it's tough, it's hard and it's very difficult."

The two are preparing to work with stem cells and hope to have real progress on drying human cells and tissue within the next two years. The Department of Defense will evaluate the project's progress in two years and decide whether to invest an additional $1.9 million into the project over two years.

Helm and Potts envision a day when astronauts embarking on multi-year missions, such as to Mars, will stock their spacecraft with stabilized, dehydrated blood and tissue products.

"There are certainly hurdles that still need to be overcome, but the proof of concept is there," Helm said.

-- Anonymous, April 08, 2001