In the life sciences, cryopreservation is the use of sub-zero temperatures to preserve structurally intact living cells. This includes tissues, cell cultures, blood, and semen.

At these extremely low temperatures, any enzymatic or chemical activity that might cause damage to the material in question is effectively stopped. Unfortunately, the method may also damage or destroy the samples, as the crystallization that occurs when water freezes may bring on harmful mechanical action.

To break that down a bit, when material freezes, ice crystals often form within it. These ice crystals can crush nearby cells, killing them or significantly damaging them. Indeed, they quite often do just this, which causes a number of problems for researchers who are working on cryopreservation.

Substances called cryoprotectants, such as ethylene glycol, are used to prevent this. However, there is a slight issue with cryoprotectants. Namely, they can be toxic. As such, they may damage or kill the very cells they are trying to protect, which is (of course) counterproductive.

But we may have a new way forward.

A New Approach

At Oregon State University, researcher just developed a mathematical model to simulate the freezing process in the presence of cryoprotectants, and they identified a way to minimize damage.

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 (water that becomes solid without freezing is said to be "vitrified").

This results in less toxicity, with healthy cell survival following vitrification rising from about 10% (with a conventional approach) to more than 80% with the new one. The researchers go on to claim that the model should also help in identifying less toxic cryoprotectants.

Progress like this may allow cryopreservation of more complex tissues, and perhaps even whole organs. 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 is found for their use. It could bring on a new era in organ donation.

Share This Article