Advantages and Disadvantages of Cryogenic Storage for Human Cells

Cryogenic storage or cryopreservation is defined as a process that preserves organelles, cells, tissues, or other biological constructs or biological products by cooling the samples to extremely low temperatures.

The research article titled, "Cryopreservation and its clinical applications," highlights the fact that both biological and chemical reactions are suspended or dramatically reduced when stored at temperatures ranging from?238 °F (?150 °C) to absolute zero or?460 °F (?273 °C), leading to the long-term preservation of cells and tissues.

The caveat here is that freezing is fatal to most living organisms because intra- and extracellular ice crystals are formed, resulting in chemical changes to the cells leading to cellular injuries and cellular mechanical constraints. Additionally, the biggest challenge for cells to overcome at low temperatures is the transition from water to ice. In summary, cell injuries occur at both fast and slow cooling rates. Ergo, cell injury at fast cooling rates is caused by the intracellular ice formation. Juxtapositionally, slow cooling rates cause osmotic changes due to the effects of interactions between cells and the extracellular ice.

Cryogenic storage solves this challenge by preserving biological samples in a state of suspended animation at the stated cryogenic temperatures over time. Secondly, it is also used to protect the original cellular structure of the human cells stored in a cryogenic storage facility.

How is cryogenic preservation performed?

Before we look at several pros and cons of cryogenic storage, let’s take a quick look at the mechanics of cryogenics.

Once the human cells have been transported to a cryogenic facility, such as our facility at Solomon Park, the freezing begins by placing the cells in a cryoprotectant and then cooling them in a rate-controlled manner. This process, also known as "vitrification (deep cooling without freezing)," aims to protect the human cells from "forming ice crystals at extremely low temperatures by putting them in a state of suspended animation."

Once in the cryoprotectant, the next step is to cool the human cells in a rate-controlled freezer until they reach -85 degrees Celsius. The last step is to store the cells in a vacuum-jacketed vessel filled with liquid nitrogen at about -320 degrees Fahrenheit (-196 degrees Celsius).

The advantages and disadvantages of cryogenic storage for human cells

Now that we have an understanding of what cryogenic storage is and how to prepare biological material for storage, let’s consider both the advantages and disadvantages of utilizing this method to store biological products, especially human cells.

1. Advantages

As described above, the fundamental aim of cryogenic storage is to preserve biological products, including human cells, for use in research projects.

A paper presented at the 47th Annual Meeting of the Society for Cryobiology held in Bristol, UK, described a research study investigating the response of mammalian cells during freezing and what damage is caused by the freezing process. In summary, the study concluded that damage during regular freezing of mammalian cells is associated with cellular dehydration and intra- and extracellular ice formation. This study also looked at different types of gel-like fluids such as glycerol as a mechanism to replace the water preventing the damage resulting from freezing the cells in their original form.

A Fourier transform infrared spectroscopy was used to study the membrane behavior and water transport during the cells’ freezing process. And in summary, the

study concluded that these frozen human cells are destroyed and unusable but removing the water and replacing it with a cryoprotective gel such as a glycerol-based chemical mixture, preserves the cells when deep cooling, not freezing. As a result, cryogenic preservation not only removes the water from the cells and adds a cryoprotection to the cells, but it also decreases the activation for water

transport at subzero temperatures.Therefore, it is critical to utilize a cold-storage mechanism that protects the cells, keeping

them usable for as long as needed. Cryogenic preservation and cryogenic storage are the best way to store biological materials indefinitely.

2. Disadvantages

While there are no disadvantages to the cryogenic preservation process, there are multiple challenges building and maintaining the cryogenic storage facilities. The building and its interior must handle frigid temperatures, down to absolute zero. The electricity or power supply must be stable without any downtime; otherwise, the temperature will start to rise, destroying the viability of the biological matter in the storage facility. Lastly, the cost of installing and maintaining a cryogenic storage facility is high, if not prohibitive. As a result, it is

essential to construct a building according to state and federal cryogen safety best practices. Install generators or battery backups to ensure that the power supply to the storage facility is constant. It is also critical to ensure that employees are trained in the safe handling of biological materials in cryogenic storage.

Conclusion

The preservation and storage of biological products, including human cells, is not a simple process and should not be attempted by individuals who are not skilled and experienced in facilitating this process from start to finish. In other words, the replacement of water by a cryoprotective gel, the deep cooling of the cells, and the long-term storage of these materials in liquid nitrogen. However, cryopreservation and cryogenic storage of human cells are integral to scientific research studies, driven by the need to improve the quality of human life by developing new treatments for existing and new medical conditions.

The good news is that Solomon Park Research Laboratories has developed the facilities to store biological products cryogenically so you don’t have to. In closing, Dr. Patric Clapshaw, founder of Solomon Park Research Laboratories, notes the value of outsourcing any cryogenic storage requirements.

"It is very difficult to properly maintain and manage your own cryogenic storage facility. By outsourcing this effort to us, your organization is free to focus on its important work."

Alex Jones is a well versed author, who has explored several new destinations and likes to write blogs to share his experiences and knowledge.