Despite advances in organ transplant technology, doctors still cart around donor organs much as they have for the last half-century—suspended in 39°F saline and packed in an ice-filled plastic cooler.

Once an organ is removed, it’s a race against time to get it to transplant, as the icy conditions can damage the tissue in a matter of hours—in as little as four hours in the case of a human heart.

But now, a team led by John Bischof, Ph.D., a Distinguished McKnight University Professor and holder of the Carl and Janet Kuhrmeyer Chair in Mechanical Engineering at the University of Minnesota, has found a way to successfully rewarm animal heart valves and blood vessels that have been preserved at temperatures of -140°C. It’s a major step toward preserving tissue for much longer periods and even establishing tissue and organ banks.

The key appears to be heating supercooled tissues quickly. But unless the tissue is tiny—smaller than a milliliter in size (about a fifth of a teaspoon)—the sample warms unevenly and ice forms in the cold spots.Bischof surmounted the problem by marinating the tissue in a solution of both cryoprotectants and iron oxide nanoparticles. The nanoparticles are coated with silica, which helps ensure that they diffuse evenly throughout the sample. He then radiated the sample with high-energy radio frequency fields, which pass harmlessly through the tissue but energize the nanoparticles, warming the tissue evenly—and quickly enough that ice crystals can’t form.

Bischof surmounted the problem by marinating the tissue in a solution of both cryoprotectants and iron oxide nanoparticles. The nanoparticles are coated with silica, which helps ensure that they diffuse evenly throughout the sample. He then radiated the sample with high-energy radio frequency fields, which pass harmlessly through the tissue but energize the nanoparticles, warming the tissue evenly—and quickly enough that ice crystals can’t form.

“The nice thing about the technology is that it is scalable. We can envision going up to a liter or even larger,” Bischof says. That would put human organs, such as kidneys and even hearts, within the realm of possibility.

Next, Bischof plans to investigate the technology’s effectiveness on rodent vessels and hearts with University of Minnesota Health transplant surgeon and Medical School assistant professor of surgery Erik Finger, M.D., Ph.D.

Says Finger, “Successful cryopreservation—or banking—of human organs and tissues could revolutionize the way organs are recovered, stored, and allocated for transplant, increasing the number of organs available and saving lives in the process.”