U.S. researchers have developed a possible approach to storing donor organs for longer, dpa reports. In the laboratory, they succeeded in gently deep-freezing animal tie parts using a special process and then reheating them just as gently and at lightning speed by means of magnetic nanoparticles in an induction field.
This could open up the possibility of storing ties and organs for the long term at some point, writes the team led by Navid Manuchehrabadi of the University of Minnesota in the journal Science Tranlational Medicine. Until now, donor organs have often had to be transplanted within hours because otherwise they are no longer functional. However, according to a German expert, it will probably be decades before the new system is ready for use.
The super-fast cooling process called vitrification has been possible for some time now. Water is removed from the cells and replaced with a cryoprotectant. This is to prevent ice crystals from forming during freezing, which would damage the tie. The process is also used for egg freezing.
The problem with organs has so far been the thawing process. It has to be done quickly and evenly so that tie is not damaged and remains functional. So far, this has only been possible on a very small scale.
Now the researchers have achieved success by introducing nanoparticles of iron oxide together with the cryoprotective agent into the tie prior to freezing. They were able to heat the particles evenly and quickly with the help of electromagnetic waves. The tie could be warmed by 100 to 200 degrees in a minute by this method. This was 10 to 100 times faster than previous methods, the researchers write.
In the 1 to 50 millimeter biological samples – including skin connective tie cells, pieces of an artery and a heart valve from a pig – a subsequent examination showed no changes in the ties. The nanoparticles could be washed out later without leaving any residue, the researchers report.
"But now the whole thing has to succeed at a higher level," co-author John Bischof emphasized in a conference call. Larger, human organs also require adapted solutions in order to freeze them intact and also to distribute the cryoprotective liquid with the iron oxide particles sufficiently.
Co-author Kelvin Brockbanck estimates that it will take seven to ten years before these problems are solved and organ banks are conceivable. Currently, hearts and lungs can be stored for about four hours, livers and pancreases for up to 12 hours and kidneys for up to 36 hours. In the U.S., according to the study, 60 percent of donor hearts and lungs are thrown away because they can't get to a recipient in time.
For Germany, however, the situation is different, emphasizes Jan Gummert (Bochum University Hospital), a heart surgeon and member of the board of the German Transplantation Society. "We don't even have enough donor organs for an organ bank. Five to ten recipients are waiting for each organ."The proportion of donor organs that would not be used would be in the per mille range. In fact, the German Organ Donation Foundation reported a low in organ donations in January.
Currently, organ freezing is not yet helping, Gummert says. "If donor organs were abundant – for example, through xenotransplants – then such a method would be useful in everyday clinical practice." Xenografts are organs grown in animals that are then implanted in humans. But it is not yet an established technology.
Gummert still sees many unanswered questions about the U.S. researchers' new storage technique. "About whether the solution can also be injected into complex organs."The transplantation expert estimates that it will take decades of research before such a procedure becomes a reality. Nevertheless, the nanoparticle project is fundamentally exciting and has great potential for other areas as well.
The U.S. researchers believe it is also possible to use induction heating in cancer medicine. Prerequisite: the nanoparticles would have to be introduced specifically into tumor cells. This could destroy the cancer cells. Similar procedures are already being tested – years ago, Charite researcher Andreas Jordan made such an approach known in the fight against brain tumors. However, according to the German Cancer Research Center, selective hyperthermia with nanoparticles is not yet particularly widespread.