20 June 2023 Elizabeth Tan

What is transient warming and how does it affect cryopreservation?

Cryopreservation is a process of preserving biological materials such as cells, tissues, and organs at extremely low temperatures, typically below -150°C, to keep them in a dormant state for extended periods of time. This process is used in a range of applications, from preserving sperm and embryos for fertility treatments to banking stem cells for regenerative medicine. While cryopreservation has revolutionized the field of biomedical research and clinical practice, there are still some challenges associated with the process. One of these challenges is transient warming. Transient warming is a phenomenon that can occur during the cryopreservation process, and it can have a significant impact on the viability of cells and tissues. Understanding the effects of transient warming during the cryopreservation process is critical to ensuring the viability of biological samples.

Transient warming occurs when a frozen sample experiences a sudden, short-term increase in temperature. This can happen during the cryopreservation process if there is a malfunction in the cryogenic equipment or when the sample is removed from the freezer. For example, when a sample that is stored together in the same box with others is removed from the freezer or liquid nitrogen tank, the rest of the samples that were not removed at the same time will suffer transient warming. Even if the exposure to warmer temperatures was just a few seconds long, it is enough to impact all the other samples that were not removed.

In addition, transient warming is present during transportation as frozen samples are being moved from one place to another. For example, when samples are moved from the manufacturer’s laboratories to the cooling equipment in the transport vehicle, or when the samples are then transferred from the transport vehicle to another transport vehicle to be flown overseas. This process repeats itself when it comes to transporting the samples from the transport vehicle to the storage facilities.

Scientists and researchers typically take great care to maintain the appropriate temperature for their frozen samples however in some cases, the gradual or minute exposures to fluctuating temperatures are unavoidable.

The effect of transient warming causes ice crystals to form within the cells, damaging the cellular structure and reducing viability. The severity of the damage caused by transient warming depends on the duration and intensity of the warming event. In some cases, the damage may be reversible, and the cells may recover once they are re-frozen. However, in other cases, the damage may be irreversible, and the cells may be rendered unusable.

Transient warming can have a range of effects on biological samples during cryopreservation. These effects can include:

Reduced viability: Transient warming can cause damage to the cellular structure, leading to reduced viability of the cells or tissue.

Decreased functionality: If the cells or tissue are damaged during transient warming, they may not function properly once they are thawed.

There are several strategies that have been developed to mitigate the risk of transient warming. One approach is to improve the handling of the cryopreserved cells, such as retrieving the vial with care, which can reduce the chances of exposing the cells to temperature fluctuations that could cause transient warming. Additionally, using specialized equipment such as liquid nitrogen storage tanks can help to maintain the appropriate temperatures during the cryopreservation process. Liquid nitrogen tanks help minimize transient warming with their thermal insulation that minimizes temperature fluctuations and some are also equipped with alarm systems, which can alert users if the temperature inside the tank rises above a certain threshold and will then help minimize the length of transient warming events.

PanTHERA CryoSolutions’ novel Ice Recrystallization Inhibitors (IRIs) have the ability to protect cells from the effects of transient warming and in turn protect cell quality post-thaw. PanTHERA’s IRIs can control ice growth during warming events, which minimizes the ice crystals’ size and therefore results in increased viability after samples have been thawed.

Transient warming is a phenomenon that can occur during the cryopreservation process, and it can have a significant impact on the viability of cells and tissues. Continued research and development are necessary to improve our understanding of the underlying mechanisms and to develop new strategies and technologies to mitigate the risks associated with transient warming. By doing so, we can continue to advance the field of cryopreservation and improve the outcomes for biomedical research and clinical practice.

About PanTHERA CryoSolutions

PanTHERA CryoSolutions is a Canadian corporation that designs and manufactures cryopreservation solutions for cells, tissues and organs for research and clinical markets. Our patented ice recrystallization inhibitor (IRI) technology exceeds other products by providing superior cryopreservation and increasing post-thaw cell recovery and function for our customers. The technology enables the use of significantly less costly storage and transportation systems limiting the need for liquid nitrogen use for some cell therapy applications.