Americans have learned to thaw the bodies without damage
Defrost without damage became possible thanks to the nanoparticles of iron oxide and induction.
Researchers American the University of Minnesota developed a new way of defrosting the bodies without damage. The work of scientists published in Science Translational Medicine, and a brief account of it is given in the message of the University. Developed by researchers method allows you to evenly warm up the frozen body at a speed of from one hundred to two hundred degrees Celsius per minute. It is dozens of times faster than modern methods of defrost.
Cryogenic freezing, or cryopreservation, is considered the most promising method to preserve donor organs. To freeze donor organs are placed in a special solution, Mary Kay. Usually it is based on glycerin or propylene glycol. This solution prevents the formation of ice crystals that can damage the cells of the body to make it unfit for further use. Cryopreservation is performed at a temperature of -196 degrees Celsius in liquid nitrogen.
Cryopreservation is used for freezing sperm, cell cultures or preimplantation embryos. Major organs or organisms are frozen relatively rare, as long as there is no reliable way safe defrosting. The fact that when slow defrosting freezing bodies covered with ice crystals that damage tissue. If preheating is to accelerate the bodies due to temperature difference inside and outside just cracking up.
A new method developed by American scientists, suggests the addition of a solution, Mary Kay nanoparticles of iron oxide coated porous silica.
This material is able to warm up quickly under the influence of electromagnetic radiation. Due to the uniform mixing of nanoparticles in crioprotector to ensure their penetration into the organ and when the food is thawed quickly and evenly heat the latter.
During the experiments, the researchers used a large heart valves and blood vessels of animals subjected to cryopreservation in a solution VS55 with the addition of new nanoparticles. Subsequently defrost setting was used with an induction coil. The capacity of the plant ranged from one to 15 kilowatts and changed by changing the induction coil. Kilowatt power is used for defrosting of samples in containers with a volume of one milliliter, and 15-kilowatt — 80 ml containers.
Defrost coil generate an electromagnetic radiation with a frequency of from one hundred to 400 kilohertz. In the experiment, the cryopreserved samples were rapidly thawed. Study using microscopy showed that the samples are not received, the cellular damage. Control fast and slow convective thawing showed the worst results, some of the samples were damaged.
After successful defrosting, the samples were washed and checked for the absence of nanoparticles of iron oxide. Control of the ultrasound and magnetic resonance imaging of nanoparticles after washing of the samples is not revealed.
In February last year, researchers from the company 21st Century Medicine managed to unfreeze the brain of a rabbit and a pig after cryopreservation, while maintaining neural connections.
For cryopreservation of organs, the scientists used a new method, called aldehyde-stabilized cryopreservation. Prior to cryopreservation in brain dead animals filed a fixing solution based on glutaraldehyde and a cryoprotectant with the addition of ethylene glycol. Then the brain of animals is cooled to -135 degrees Celsius.
Then the researchers thawed the brain of animals, and removed fixative solution and a cryoprotectant, and analyzed the state of the brain using electron microscopy. It turned out that the freezing and subsequent thawing did not affect the microstructure of synapses. They have remained intact. Researchers believe that in the future this will also allow cryopreservation of the brain with preservation of long-term memory.
Vasily Sychev