Cryovials

How are Cryovials stored?

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Cryovials are small, specialized containers used to store biological samples at extremely low temperatures, typically in liquid nitrogen or ultra-low-temperature freezers. These samples can include cells, tissues, blood, DNA, RNA, proteins, or other biological specimens that need to be preserved for long-term research or medical use. Proper storage of cryovials is crucial to maintaining the integrity of the samples. In this blog post, we will explore the key steps and considerations involved in storing cryovials effectively.

What Are Cryovials?

Cryovials are constructed from durable plastic, typically polypropylene, which can endure freezing temperatures without cracking or leaking. They are equipped with secure screw caps or snap caps featuring silicone O-rings to prevent contamination and ensure an airtight seal. Cryovials are available in different sizes ranging from 1.0 mL to 5.0 mL, depending on the volume of the sample being stored.

Why Proper Storage Is Important

Biological samples are very sensitive to changes in their environment. Improper storage can result in the degradation or contamination of samples, which in turn could compromise the results of experiments or medical treatments. Temperature fluctuations, exposure to contaminants, and improper handling can all have negative effects on the quality of stored samples. Therefore, it is essential to understand how to store cryovials properly in order to preserve the integrity and viability of the samples.

Steps to Store Cryovials

Labeling the Cryovials

Before storing cryovials, it is important to clearly label them. The labels should include information such as the type of sample, the date it was stored, and any identification numbers. It is crucial to use labels or markers that will not come off or fade in low temperatures, as this information will be needed later when retrieving the samples.

Preparing Samples for Storage

Some samples require special preparation before they can be stored. For example, cells might need to be mixed with a cryoprotectant, a substance that helps protect them from damage during freezing. This step is important to ensure that the samples survive the freezing process and can be used later.

Freezing the Samples

After preparing the samples, the next step is to freeze them. The way samples are frozen can affect their quality. Ideally, samples should be frozen slowly using a controlled-rate freezer, which gradually lowers the temperature. This slow cooling helps prevent ice crystals from forming inside the cells, which can cause damage. If a controlled-rate freezer is not available, samples can be placed directly into a -80°C freezer.

Long-Term Storage

When cryovials are frozen, they must be stored in an environment that maintains their extremely low temperature. There are two common methods for long-term storage: 

  • Liquid Nitrogen Storage: Liquid nitrogen keeps samples at around -196°C, which is the coldest storage option. Cryovials can be stored either immersed in the liquid nitrogen or suspended in the vapor above it. Storing in the vapor phase is often preferred to reduce the risk of contamination. Special racks or canisters are used to keep cryovials organized and easy to access within the storage tank. 
  • Ultra-Low Temperature Freezers: These freezers maintain temperatures between -80°C and -150°C. While not as cold as liquid nitrogen, these freezers are often more convenient for everyday use and accessing samples.

Handling Cryovials

When dealing with cryovials, it’s crucial to limit their exposure to higher temperatures. Using tools such as cryo racks, tongs, or insulated gloves can help prevent the samples from thawing and refreezing, which can cause damage. Cryovials should be moved swiftly from storage to their next destination, whether for thawing or additional freezing.

Thawing the Samples

When it’s time to use the samples, they need to be thawed carefully to avoid damaging them. Thawing is usually done quickly in a warm water bath to ensure that the sample thaws evenly. Once thawed, the samples should be used or processed according to the specific requirements of the experiment or medical procedure.

Best Practices for Storing Cryovials

  • Regularly check the temperature of storage units to ensure they are functioning properly.
  • Avoid repeated freeze-thaw cycles by storing samples in smaller portions.
  • Keep a detailed inventory of stored samples to easily locate them.
  • Store duplicates of important samples in a separate location as a backup.
  • Ensure everyone handling cryovials is trained in proper storage and safety techniques.

Storing cryovials properly is essential to ensure that biological samples remain safe, uncontaminated, and usable over time. By following proper labeling, freezing, and storage techniques, you can preserve the integrity of your samples for future use. Whether using liquid nitrogen or ultra-low temperature freezers, the key is to maintain consistent conditions and handle samples with care. This way, you can protect the valuable research and medical data stored within these tiny, but crucial, containers.