Last Updated on November 28, 2023

Cryopreservation is a remarkable scientific process that allows us to preserve cells and tissues under low-temperature conditions, preventing cell injury or death. It offers a means to store cells for future use, ensuring their viability and functionality even after years of preservation. In this article, we delve into the fascinating world of cryopreservation and explore the critical aspect of cell viability after cryopreservation.

Understanding Cryopreservation

Cryopreservation involves freezing cells or tissues at temperatures ranging from -80˚C to -196˚C. The traditional methods include using liquid nitrogen, direct freezing in a freezer, or employing dry ice (carbon dioxide). The primary goal of cryopreservation is to maintain the viability and cellular function of the preserved cells.

The Crucial Role of Cell Viability

Cell viability is the measure of living cells capable of dividing, multiplying, and maintaining their cellular functions when cultured. After the cryopreservation process, the viability of cells becomes paramount. If cells are frozen too rapidly, ice crystals can form, damaging the cell membrane and leading to cell death. However, when cells are cryopreserved correctly, they can be thawed and revived to function normally.

Mechanical and Metabolic Stresses

Freezing and thawing cells impose mechanical and metabolic stresses that can compromise their viability. During this process, intracellular metabolites are released, potentially resulting in cell death or sub-optimal viability. Moreover, the freezing velocity, which refers to the time and temperature at which a cell is frozen down, significantly impacts cell viability.

The Culprit: Intracellular Ice Crystals

The formation of intracellular ice crystals during the freezing process can be detrimental to cell viability and survival. Damage can occur due to extensive cell dehydration (known as the “solution effect”) or mechanical strain caused by the formation of ice crystals (“mechanical damage”). Often, it is a combination of both factors. Sub-zero temperatures lead to the formation of ice crystals and nucleation sites in the cytoplasmic fluid, subjecting cells to additional mechanical stress and varying levels of damage. To minimize these effects, cells should be frozen slowly at low temperatures, maintaining a constant level of ice crystals throughout the freezing process.

The Journey of Recovery

Cells possess an incredible ability to recover after cryopreservation. Upon thawing, cells begin the process of recovering from the freezing trauma and re-adapting to their original homeostasis. The duration of recovery depends on the cryopreservation technique and the species of the sample. Typically, the majority of cells can fully recover within approximately two weeks. However, there are reports suggesting increased or decreased recovery rates over time, emphasizing the need for further research.

Factors Affecting Recovery Time

Apart from the duration of freezing, the number of times the sample is thawed and the thawing temperature can significantly impact the recovery time. Cells exposed to higher temperatures during thawing may experience more damage and require a longer recovery period.

Introducing the CytoSAVER Controlled-Rate Freezer

To enhance the viability and efficiency of cryopreservation, the CytoSAVER controlled-rate freezer is an invaluable tool. Unlike traditional methods, this innovative system does not require liquid nitrogen, eliminating the risk of contamination. It enables easy programming of custom freezing protocols, and the samples are loaded into an aluminum freezer block for cryopreservation.

Equipped with a powerful Stirling engine, the CytoSAVER cools cells to -80°C without relying on liquid nitrogen. Three temperature sensors monitor the freezing process and generate an automatically generated report. This comprehensive report provides valuable information about the freezing parameters, ensuring precise control and optimization of the cryopreservation process.

The Three Critical Stages for Increased Viability

  1. Pre-Freezing Preparation:
    Before freezing, the sample must be transferred to the culture media containing a cryoprotectant such as dimethyl sulfoxide (DMSO) or glycerol. This step protects the cells from damage during the freezing process. It is essential to maintain the sample at 4°C during this preparation phase.
  2. Controlled Freezing:
    Achieving an optimal freeze rate is essential for maximizing cell viability. The “Goldilocks” freeze rate is typically around 1°C per minute, but the optimal rate may vary depending on cell-specific factors such as surface area and permeability. A gradual temperature decline during freezing is crucial for minimizing the formation of ice crystals and reducing mechanical stress on the cells.
  3. Proper Storage:
    After completing the freeze-down process, the sample should be transferred to cell deep storage. Using dry ice during transportation is acceptable and ensures the maintenance of low temperatures during transfer, preserving cell viability until long-term storage is established.

Cryopreservation and Cell Viability – Conclusion

Cryopreservation is an indispensable technique for preserving cells and tissues, allowing us to unlock their potential for future research and applications. Cell viability after cryopreservation is of utmost importance, and the CytoSAVER controlled-rate freezer offers a cutting-edge solution to enhance viability and efficiency.

With its user-friendly interface, precise temperature control, and elimination of liquid nitrogen requirements, the CytoSAVER revolutionizes the cryopreservation process. By following the three critical stages of pre-freezing preparation, controlled freezing, and proper storage, researchers can maximize cell viability and unlock the full potential of their preserved samples.

To discover more about the CytoSAVER controlled-rate freezer and how it can revolutionize your research, request an online demo today. Experience the power of precise cryopreservation and embark on a journey of discovery with preserved cells that retain their viability and functionality, ready to contribute to groundbreaking scientific advancements.