‘Antifreeze protein’ could be the breakthrough that finally enables long-term banking of donated organs
Donated blood can be refrigerated and stored for six weeks. But donated organs have a very short shelf life. A heart or lung can be kept viable for transplantation for only six hours, a pancreas or liver for 12 hours and a kidney for less than 30 hours. Any donated organ that is past its prime ends up going to waste instead of saving lives.
Freezing organs, rather than just refrigerating them, seems like a logical solution, but in practice it doesn’t work. When organs are frozen, ice crystals form and cause irreversible damage to the cells.
“The ability to freeze organs and to then thaw them without causing damage to the organ itself would be revolutionary in terms of our chances to save lives,” says Prof. Ido Braslavsky from the Institute of Biochemistry, Food Science and Nutrition at the Robert H. Smith Faculty of Agriculture, Food and Environment in The Hebrew University of Jerusalem.
Together with his Hebrew University team, Braslavsky is contributing significantly to the effort to perfect cryopreservation – the process of preserving cells, tissues and organs in sub-zero temperatures.
This would enable long-term banking of tissues and organs and efficient matching between donor and patient, eventually saving lives of millions of people around the world.
Braslavsky’s work was recently featured in an article in The Economist titled “Wait Not in Vain.”
The article reports that research in cryopreservation is heating up around the world. The Organ Preservation Alliance, an American NGO established in 2014, aims to accelerate and coordinate research toward banking of human organs. And last year’s inaugural global Organ Banking Summit brought together world-leading scientists, investors and policy-makers to discuss how to transform organ transplantation.
Braslavsky’s area of specialty is so-called “antifreeze proteins,” ice-binding proteins that help organisms resist or withstand freezing in water and on land by inhibiting the formation and growth of crystalline ice.
Ice-binding proteins were discovered some 50 years ago in Antarctic fish and are now known to exist in cold-resistant fish, plants, insects and microorganisms.
In contrast to other types of antifreeze substances, ice-binding proteins are needed in very low amounts to do the job effectively.
“We investigate the interaction of ice-binding proteins with ice crystals,” Braslavsky explained. “Since we are working at temperatures of sub-zero Celsius degrees and we need high accuracy of working temperature, we designed a specialized microscope with a stage cooler that allows a millidegree-level control of temperature and also freezing.
“Using fluorescent illumination, we can see where the proteins, which are tagged with fluorescent dyes, are located. With these devices, we can follow ice crystals as they grow and melt in the presence of ice-binding proteins.”
Braslavsky and his team collaborated with Prof. Peter Davies from Queens University in Canada to investigate the mystery of exactly how ice-binding proteins stop the formation of ice crystals.
They discovered that antifreeze proteins bind permanently with ice. “We found that proteins in insects are much more efficient in inhibiting ice growth than proteins in fish, but fish proteins bind faster to ice,” said Braslavsky.
For organs and food
This finding, published in the journals Langmuir and RSC Advances in 2015, could be crucial for the advancement of using these proteins to help preserve frozen organs as well as frozen foods.
“Ice growth also poses a major problem in frozen food,” said Braslavsky, whose team is looking into the implementation of ice-binding proteins in food.
“Many are familiar with ice cream that has lost its texture in home freezers, or meat that has lost a lot of its liquids and doesn’t look or taste fresh after thawing. Ice-binding proteins may allow the control of ice in frozen food and the developments of new frozen treats. Some food manufacturers have already started using ice-binding proteins in their products.”
Braslavsky’s pioneering work in studying the interaction between antifreeze proteins and ice is now expanding to developing cryopreservation techniques that will allow revival of cells and tissues while restoring their form and function.
His research is supported by the European Research Council, the European Union’s Seventh Framework Programme (FP7), and the Israel Science Foundation.
Braslavsky is hopeful that cryopreservation research is on the doorstep of success. “Recent developments in cryobiology methodologies and the use of materials with specific interaction with ice crystals such as ice-binding proteins open the possibility for significant advancement in cells and organs cryopreservation,” he said.