On daily basis, people die waiting for an organ transplant. Time is at a premium, not only for those awaiting organs, but additionally for the organs themselves, which might deteriorate rapidly during transportation. Seeking to extend the viability of human tissues, researchers report in ACS’ Nano Letters their efforts to facilitate completely freezing, reasonably than cooling after which thawing, potentially life-saving organs. They reveal a magnetic nanoparticle’s successful rewarming of animal tissues.
As of August 2024, greater than 114,000 persons are on the U.S. national transplant waiting list, in accordance with the Organ Procurement and Transplantation Network, and about 6,000 annually will die before receiving an organ transplant. One reason is the lack of organs in cold storage during transportation when delays cause them to warm prematurely. Methods have been developed to quickly freeze organs for longer-term storage without risking damage from ice crystal formation, but ice crystals can even form during warming. To handle this problem, Yadong Yin and colleagues advanced a method often known as nanowarming, pioneered by collaborator John Bischof, to employ magnetic nanoparticles and magnetic fields to thaw frozen tissues rapidly, evenly and safely.
Recently, Yin and a team developed magnetic nanoparticles — effectively extremely tiny bar magnets — that, when exposed to alternating magnetic fields, generated heat. And that heat rapidly thawed animal tissues stored at -238 degrees Fahrenheit (-150 degrees Celsius) in an answer of the nanoparticles and a cryoprotective agent. The researchers fearful, nevertheless, that uneven distribution of the nanoparticles throughout the tissues might trigger overheating where the particles congregated, which may lead to tissue damage and toxicity from the cryoprotective agent at elevated temperatures.
To cut back these risks, the researchers have continued their investigation, working on a two-stage approach that more finely controls nanowarming rates. They describe this process in the brand new Nano Letters study:
- Cultured cells or animal tissues were immersed in an answer containing magnetic nanoparticles and a cryoprotective substance after which frozen with liquid nitrogen.
- In the primary stage of thawing, as before, an alternating magnetic field initiated rapid rewarming of animal tissues.
- Because the samples approached the melting temperature of the cryoprotective agent, the researchers applied a horizontal static magnetic field.
- The second field realigned the nanoparticles, effectively tapping the brakes on heat production.
The heating slowed fastest in areas with more nanoparticles, which dampened concerns about problematic hotspots. Applying the tactic to cultured human skin fibroblasts and to pig carotid arteries, the researchers noted that cell viability remained high after rewarming over just a few minutes, suggesting the thawing was each rapid and protected. The power to finely control tissue rewarming moves us one step closer to long-term organ cryopreservation and the hope of more life-saving transplants for patients, the researchers say.
The authors acknowledge funding from the U.S. National Science Foundation.
