So You’d Like to Freeze Your Kidneys?
Cryotherapy research holds new promise for organ transplants
Transplanting human organs is a delicate, time-sensitive business. Organs must be harvested from donors, a recipient quickly identified, and the organ raced to the hospital as the patient is prepped.
And there is a perennial need for far more organ donors than we currently have.
But what if in the future, doctors could just go to a library of organs and simply pull out the perfect donor organ for their patient? Termed “cryopreservation,” this may be closer to happening than most people think as advances continue in freezing donated organs for later use.
People directly affected will cheer the advances. Mike Atkinson, 56, a native of San Diego, California, received a kidney from a donor last December after suffering from kidney disease. He has shared his transplant journey on his popular blog mikeyskidney.wordpress.com.
“Because of my health journey, I’ve been closely following the amazing amount of advances the medical research community has been spearheading in their efforts to reduce the death rate of kidney disease patients,” he told LifeZette. “Just the thought of a selection of kidneys to choose from for the sickest of patients is truly amazing.”
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The interest in cryopreservation started with an innocent little fellow called the North American wood frog. In an average winter, this type of frog routinely freezes solid several times. The wood frog achieves this by replacing most of the water in its body with glucose, which is stored in its liver. The glucose prevents ice from forming in the tissues.
Eventually, the tree frog unthaws and gets back to hopping around. Scientists have been studying this North American wood frog and other creatures like it, attempting to emulate the animals’ ability to freeze and unthaw naturally.
“We are looking at (species) that freeze and asking ourselves how they do it, and how we can translate that into organ cryopreservation,” Dr. John Baust, director of the Institute of Biomedical Technology at Binghamton University, told LifeZette. “We are moving in that direction very successfully at present, addressing both the biophysical as well as molecular and biological factors in how a human cell responds to freezing.”
Science will meet a serious need if it successfully achieves cryopreservation.
The World Health Organization estimates that less than 10 percent of the needed organs are available. This is due in part to advances in intensive care that save would-be donors’ lives, and the advances in car safety that save lives, too. Both are good things, but more people are left needing an organ transplant, with limited odds of it happening.
A donated kidney is only viable for 12 hours at most. Film and TV dramas in which white-coated medical personnel board a helicopter to fly an organ packed in dry ice to a waiting recipient closely mirror what actually happens.
The problem with freezing organs is a basic one: Water naturally found in the organ’s tissues expands as it freezes, damaging the organ. While science has successfully frozen sperm and red blood cells, those items are not water-intensive. Organs are a different matter.
“Freezing is hard on both organ tissues and cells,” said Baust. “Much of what we talk about is this cell stress, which causes cells to die.”
Dr. Mehmet Toner of Harvard has found a way to duplicate what the wood frog does naturally, by introducing trehalose — which, like glucose, is also a sugar — into the cryopreservation process. Toner also sprinkles the trehalose with molecular bits called acetyl groups. That allows the trehalose to be more absorbable in organ cells.
In June of last year, Toner and his colleagues showed that frozen rat cells could be revived using this process.
Another issue science is addressing is the thawing process. Thawing must be done quickly and uniformly — or, as Dr. John Bischof of the University of Minnesota told The Economist — “the organ cracks like an ice cube dropped in water.”
Baust reinforced this. “Unfreezing is problematic. How do we get organs to successfully recover from being frozen?”
One team of researchers in Israel is looking at avoiding deep-freezing the organ altogether yet still significantly lowering its temperature, while Bischof and his team have added magnetite, a form of iron oxide, to the cryoprotectant. When the organ is immersed in a magnetic field, the magnetite infused into the organ tissue will heat up both quickly and uniformly.
A major player in cryopreservation advances is the Organ Preservation Alliance, which has successfully brought together funding from venture capitalists, philanthropists, charities and even the Department of Defense.
Begun by Stanford researchers, the Organ Preservation Alliance “has in a major way reorganized transplant activities,” said Baust. “They have brought in the government, and DOD has awarded five or six grants to cryopreservation research in the past few months.”
The DOD’s interest is a natural one, noted Baust. “Being able to save digits, hands, and organs for our servicemembers is of course of interest to them.”
Another important benefit to a future organ “library” would be decreased need for desperate patients to look to the black market for organs, including in China or Iran, he said.
Kidney recipient Mike Atkinson believes the future of organ transplantation looks rosy. “Within years we could pull back the horrifying statistic that 18 people on wait lists die each day due to lack of supply. What a happy day that will be, for patients and their families.”