The research is supported by
The first human whole organ transplant 60 years ago -- a living kidney transplant -- changed the landscape of the medical world. Since then, transplants of skin, kidneys, hearts, lungs, corneas, and livers have become commonplace but due to a shortage of donor organs, more than 120,000 patients are still on waitlists for organ transplantation in
Current technology can preserve livers outside the body for a maximum of 24 hours using a combination of cold temperatures and a chemical solution developed by scientists at the
The difficulty with long-term preservation of human organs stems mostly from the extensive tissue damage that occurs when organs are cryopreserved, frozen at temperatures of -320.8 degrees Fahrenheit. While successful for single cells and simple tissues, the problem is exacerbated with whole organs because of the multiple cell types and other structures that react differently to cold. To combat these problems,
The livers were then slowly cooled below the freezing point, to 21 degrees Fahrenheit, without inducing freezing -- thereby supercooling the organ for preservation. After storing the organs for several days, the researchers again used machine perfusion to rewarm the organ, while also delivering oxygen and other nutrients to prepare the organ for transplantation.
Using this new technique, the researchers were able to store the supercooled rat livers for three days (72 hours) and four days (96 hours) at 21 degrees Fahrenheit. All the rats who had supercooled livers stored for three days survived three months, but none of the rats who had transplants using current methods did. The survival rate for animals receiving livers stored for four days was 58 percent. When testing to see if all the steps in their method were essential, the researchers found that if they eliminated the supplemental components PEG-35kD or 3-OMG, none of the rats survived for even a week. If they did not use machine perfusion or supercooling, death occurred within an hour of transplantation.
"The next step will be to conduct similar studies in larger animals," said
The process must go through extensive testing and refinement before it could be considered for use in humans. But the technique's achievement in being the first method to have a successful survival rate after the livers had been stored for three days and possible potential for four-day storage has broad implications for the future of liver transplantation.
"The longer we are able to store donated organs, the better the chance the patient will find the best match possible, with both doctors and patients fully prepared for surgery," said Hunziker. "This is a critically important step in advancing the practice of organ storage for transplantation."
Among the researchers contributing to this project are
This work was supported by
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