Cooling organs to subzero temperatures could help them last longer, making lifesaving transplants available to more people.
A new technique to keep donor organs colder than ice cold could greatly extend the length of time that those organs are viable for transplant.
Typically, donor organs stay viable for several hours on ice at about 4° Celsius. Tissue can last even longer at lower temperatures — but below zero degrees Celsius, the formation of ice crystals risks damaging an organ and rendering it unusable. Now, using chemicals that prevent an organ from freezing at subzero temperatures, researchers have preserved five human livers at –4° C. That supercool storage system tripled the livers’ typical shelf lifefrom nine to 27 hours, researchers report online September 9 in Nature Biotechnology.
This kind of deep-chill technology “would be huge for transplantation,” says Jedediah Lewis, president and CEO of the Organ Preservation Alliance in Berkeley, Calif., a nonprofit that supports research on organ and tissue preservation but was not involved in this research.
Every year, thousands of donor organs are discarded for various reasons, including the inability to find a suitable patient close enough to receive the organ before it goes bad. If donor tissue were viable longer, doctors could get organs to patients who might otherwise be too far away, Lewis says. That could lead to more lifesaving surgeries for patients waiting for a transplant — currently more than 100,000 in the United States alone. Pushing back organs’ expiration dates could also curb the costs of private flights to rush organs between cities and allow for more flexible surgery scheduling, Lewis adds.
In the new study, researchers devised a cocktail of cryoprotectant chemicals, including trehalose and glycerol, to combat ice formation and protect cells at extremely cold temperatures. To ensure each liver was completely saturated with preservatives, the researchers administered the chemicals using a machine perfusion system. That device is basically “an artificial body for the liver” that pumps fluids into an organ in a way that imitates blood flow, says Reinier de Vries, a medical doctor and mechanical engineer at Harvard Medical School and Massachusetts General Hospital in Boston.