New Discovery To Cryopreservation Of Tissues & Organs

Researchers in the College of Engineering at Oregon State University have discovered a new approach to "vitrification," or ice-free cryopreservation, that could ultimately allow a much wider use of extreme cold to preserve tissues and even organs for later use. 

Cryopreservation, the freezing of biological material for preservation purposes, is already in widespread use for applications, such as saving semen, embryos, blood, and plant seeds. When it comes to tissues and organs, however, the process is more problematic.

"This could be an important step toward the preservation of more complex tissues and structures," said Adam Higgins, an associate professor in the OSU School of Chemical, Biological and Environmental Engineering, and expert on medical bioprocessing.

The issue with cryopreservation is that crystallization often occurs when water freezes; this risks damaging the tissues and cells the process is meant to preserve, Higgins explained. It is for this reason that the researchers explored various types of cryoprotectants aimed at reducing cell damage during the freezing process. One of these is ethylene glycol, also known as the compound used in automobile antifreeze.

To address this, researchers have used various types of cryoprotectants that help reduce cell damage during the freezing process - among them is ethylene glycol, literally the same compound often used in automobile radiators to prevent freezing.

In the new OSU research, the engineers developed a mathematical model to simulate the freezing process in the presence of cryoprotectants, and identified a way to minimize damage. They found that if cells are initially exposed to a low concentration of cryoprotectant and time is allowed for the cells to swell, then the sample can be vitrified after rapidly adding a high concentration of cryoprotectants. The end result is much less overall toxicity, Higgins said.

The study showed that the survival rate for healthy cells following vitrification rose from around 10 percent with a traditional approach to over 80 percent with the new process.

"The biggest single problem and limiting factor in vitrification is cryoprotectant toxicity, and this helps to address that," Higgins said. "The model should also help us identify less toxic cryoprotectants, and ultimately open the door to vitrification of more complex tissues and perhaps complete organs."

Such an accomplishment would open the door to a great number of applications of vitrification. The advancements in tissue regeneration and stem cell use are closely intertwined: one goal would be creating tissue in small amounts and storing them until they’re needed for transplantation. Organs for transplants could be safely preserved until a precise immunological match was found for their use.

Tissues could be made in small amounts and then stored until needed for transplantation. Organs being used for transplants could be routinely preserved until a precise immunological match was found for their use. Conceptually, a person could even grow a spare heart or liver from their own stem cells and preserve it through vitrification in case it was ever needed, Higgins said.

Drug testing is now carried out with traditional cell culture systems or animal models, which in many cases don't accurately predict the effect of the drug in humans. To address this, researchers are developing "organs-on-a-chip," or microfluidic chambers that contain human cells cultured under conditions that mimic native tissues or organs.