Potential Breakthrough For Organ Transplants As Heart Deep Frozen And Successfully Rewarmed
In what may well be a major breakthrough in medicine, scientists have managed to successfully cryogenically freeze and then rewarm large portions of heart tissue, without damaging or breaking the cells. It is hoped that the new technique will pave the way for entire organs to be frozen and thawed, a move that would revolutionize organ donation.
The ability to freeze organs that could then be used for transplants weeks, even months, later would transform transplantations. While freezing human tissue can be done, the problems arise as they are then defrosted. The cells of the organs tend to crack and burst, turning them to mush. This means that organs can only be stored for a maximum of four hours on ice before they are rendered useless. Because of this, around 60 percent of donated organs have to be thrown away.
But now, researchers have managed to develop a technique that has allowed them to successfully warm up large portions of tissue, keeping all the cells largely intact. It involves infusing the tissue with magnetic nanoparticles made from silica-coated iron oxide. These particles are dispersed throughout the cryopreservant, before the tissue is subjected to preservation methods, such as vitrification, which cools the tissue to such a degree it effectively turns it to glass.
When it then comes to defrosting the tissue, the nanoparticles act like tiny heaters within the tissue itself. When activated by noninvasive electromagnetic waves, the particles rapidly and, importantly, uniformly warm up the tissue.
“This is the first time that anyone has been able to scale up to a larger biological system and demonstrate successful, fast, and uniform warming hundreds of degrees Celsius per minute of preserved tissue without damaging the tissue,” explained John Bischof, senior author of the study published in Science Translational Medicine.
While previous studies had only managed to successfully freeze and then rewarm portions of tissue no larger than milliliters in size, this latest study has blown this out of the water by managing to do it on pieces of heart up to 50 milliliters in volume. But more importantly, the researchers believe that it will be possible to scale the process up, and see no reason why it might not work on much bigger pieces, and even whole organs.
It is estimated that if only half of all unused organs could be saved and successfully transplanted, then within in a few years all organ waiting lists would be cleared. The team now plan on testing whether or not the nanoparticles could achieve this, first by trying it on rat and rabbit organs, then moving onto pigs, before finally trying it out on human organs.