In a small laboratory on the University of Wisconsin campus, a group of scientists are raising ground squirrels. While the animals are hibernating in a cold, dark laboratory, scientists observe the animals and examine their physiological changes.
During the six–month hibernation cycle, scientists are trying to determine how their organs are able to shut down for weeks at a time, while enabling the animals to stay alive at body temperatures close to freezing.
Ultimately, these scientists are looking for ways to increase the preservation of human organs prior to transplant by adapting proteins in the tissues to have similar characteristics of the hibernating ground squirrels.
Dr. Jim Southard of the UW department of surgery, division of transplant, is working in collaboration on the study.
“By improving the preservation of organs, it means more people can receive this gift, and limit the amount of organs that are wasted,” he said.
According to the United Network for Organ Sharing, over 80,000 people are currently waiting for an organ transplant today. More than 24,000 lives were saved in the United States last year thanks to organ transplants, according to a release by UNOS. However, over 6,000 lives were lost in the same year by people put on waiting lists for organs.
Organs are currently preserved in a solution invented at the University of Wisconsin known as the UW cold–storage solution. It is held at 4 degrees Celsius, similar to the body temperature of a hibernating ground squirrel. This solution preserves organs, but not for very long.
“Livers can be preserved for one to two days, but hearts and lungs are only good for four to six hours,” Southard said.
Southard emphasized that if science could come up with a way to preserve these precious items for a longer period of time, then every organ donated by one life would mean another life could be spared.
Dr. Hannah Carey, professor of comparative biosciences at UW, is studying the liver tissue of thirteen–line hibernating ground squirrels and comparing them to rat liver tissue (a non–hibernating animal) to find differences in the genetic makeup.
“My goal is to make a rat liver have similar qualities to a ground squirrel liver,” Carey said. “This research can give us hints on how to increase the tolerance and time storage of human preserved organs.”
Carey’s experiments allow her to harvest livers from both rats and ground squirrels and then run tests to determine their tolerance to storage time. She discovered that after only 24 hours of storage, the rat livers had gone down hill. Meanwhile, the liver of ground squirrels went relatively unchanged.
“After 96 hours the squirrel livers were doing fine and there were no significant changes,” she said.
Dr. Sandy Martin, professor at University of Colorado in the Health Sciences Center, is involved in the project by examining the liver tissues.
“The ultimate goal of this study is to increase the ability of rat livers to withstand storage, by using the model system of the squirrels,” Martin said. “The next step would be to apply this discovery to humans.”
This “discovery approach” to research is comparing protein profiles to see how they change between rat and ground squirrel livers to find the candidate, or specific molecule, that is helping ground squirrels’ livers to stay preserved.
A likely hypothesis, Martin said, could be the production of “stress proteins.” These proteins are produced in humans when an injury occurs, and by attaching a stress protein to a weakened one, it helps to stabilize cells in the body. It could be that squirrels carry an abundance of these proteins at all times, enabling their bodies to go into a “torpor,” or hibernation, state.
After hearing about the research, the Defense Department granted Carey and Southard over $1 million dollars in funding last summer to continue the study.
“They are interested in new ways of improving trauma care for military personal,” said Carey.
The Department of Defense’s hope is to safely change metabolism in order to put an injured soldier into a “stasis kind of state,” until they can be airlifted to a hospital, Carey said. She thinks it is likely for medicine to be able to do this.
“Induced hypothermia is already used in some trauma and surgery situations,” she said. “There is still a lot they don’t know.”
Dr. William Burlingham, associate professor at UW in the department of surgery, said this research could be beneficial to people by giving their bodies more time to prepare for surgery to limit the chance of organ rejection.
“[Increasing organ preservation] would allow time to modify the immune system of a patient to accept a transplant without any long–term drug treatment,” Burlingham said.