Here's a distressing statistic: More than 60 percent of hearts and lungs collected for organ transplant are thrown away. That's because the window of time in which a newly harvested organ is safe to transplant is very small: about four hours for hearts and lungs; eight to 12 hours for livers, intestines, and pancreases, and 36 hours for kidneys. Meanwhile, people who need organ replacements are waitlisted for years.

Scientists have made great progress in freezing tissue and organs, but they haven’t yet figured out a way to safely thaw them out. We may have gotten one step closer to solving that problem: A paper published today in the journal Science Translational Medicine describes a new method of safely defrosting cryopreserved human tissue.

Vitrification is a preservation method in which the liquids inside an organ are transformed into crystals or glass through deep cooling. It works well until it’s time to reheat the now-fragile tissue, which tends to crack unless the heat is perfectly distributed. If we could just spread that heat evenly, vitrification could be an answer to the puzzle of longer-term organ storage.

In the current study, researchers at the University of Minnesota developed a solution made with magnetic nanoparticles and injected it into pig hearts and arteries, as well as human skin tissue, before they were frozen. Then they applied electromagnets to the frozen tissue. Sure enough, the vibration of the nanoparticles was quick, gentle, and uniform enough to reheat the tissue samples without damaging them. The nanoparticles were then completely washed out of the tissue.

Existing techniques (L) and the new nanoparticle method (R). Image credit: Manuchehrabadi et al. 2017. Science Translational Medicine.

 
Pig hearts and skin cells are, of course, not the same as whole organs, and it will likely be years before the technology can be translated to human hearts and kidneys. “We are cautiously optimistic, but we’re not declaring any victory yet,” senior author John Bischof said in a press briefing. “There are some huge scientific hurdles ahead of us.”

Nor should we put all our chips on cryonics. “Cryobiology and cryonics don’t really mix,” Bischof said. “We try to stay science-based. While it’s attractive to think that maybe one day we’ll be able to freeze down and bring back whole people, or their heads, we are still so far away from that.”