Superior Pathology

Biospecimen Storage & Preservation: A Guide for Researchers

Biospecimens are a key part of modern scientific research. After collection, tissue samples are preserved and prepared for distribution, ensuring researchers receive only the highest-quality tissue samples. During the preservation process, it’s vital to maintain biospecimens’ original structures and molecular makeups. One misstep in this process could compromise the tissue sample’s effectiveness for research purposes and drug development. This information raises the question: how exactly do you store biospecimens effectively?

In this blog post, we share everything you need to know about biospecimen storage. We answer common questions such as, “What’s the best way to preserve tissue samples?” and “Why is tissue preservation important?” We also share 3 best practices for the tissue preservation process. Keep reading to find out how you can keep tissue samples in top condition from collection to distribution!

Why is Tissue Preservation Necessary?

Proper biospecimen storage is a vital element of scientific research. Whether you’re preparing tissue samples for microscopic slides or need to extract the biospecimen’s molecules for DNA and protein analysis, tissue preservation is a skill you need to learn or, at the very least, understand.

Human tissue samples for use in oncology, spatial biology, pathology, and other biological research fields can lose their integrity and reliability without the proper temperatures and preservation conditions. The primary purpose of tissue preservation is to maintain the tissue’s original molecular and structural state without losing quality and deterioration.

Tissue preservation is especially important for long-term research and studies. Well-preserved biospecimens can be stored at a biobank for countless years, providing invaluable resources for a variety of medical research purposes. Long-term tissue sample storage allows researchers to re-examine high-quality biospecimens over the years in light of new scientific discoveries or upgraded techniques. 

Let’s take a look at a few of the best preservation methods for tissue samples.

3 Common Preservation Techniques Used for Human Tissue Samples

There is a diverse range of preservation methods within biospecimen storage. From freezing tissue samples in extremely low temperatures to fixating specimens in chemicals, tissue preservation is a learned science all on its own. However, the scientific community has relied on several popular preservation methods over the past few decades. Below are the 3 common preservation techniques scientists use for biospecimen storage

Snap-Frozen and Cryopreservation

Perhaps the most well-known preservation method is the act of freezing tissue samples. Scientists take one of two paths when freezing biospecimens: snap-freezing or cryopreserving. Let’s take a closer look at each of these preservation processes: 

Snap-freezing is the process of rapidly cooling tissue samples to temperatures below -70℃ using dry ice or liquid nitrogen. If using liquid nitrogen, researchers will place collected biospecimen samples on a cryomold or wrap them in foil, immerse them in the nitrogen, and immediately freeze them. On the other hand, researchers can use the dry ice method, placing the specimen on prepared dry ice. This method takes longer than liquid nitrogen and isn’t the preferred method. Snap-frozen tissue samples are stored in -80℃ freezers.

Cryopreservation is a long-term method of preserving samples at very low temperatures (-196℃ to -250℃) to preserve the overall integrity of cells and tissue. Cryopreservation involves the use of cryoprotectants (e.g., ethylene glycol, dimethyl sulfoxide, glycerol, etc.) to protect biospecimens from damage during the preservation process, specifically from ice crystals forming. 

Freezing tissue samples, whether through cryopreservation or snap-freezing, is a reliable preservation method used for long-term biospecimen storage. Tissue samples can be frozen for several years, maintaining their original structure and quality for an extended period.

Formalin-Fixed Paraffin-Embedded

Chemical fixation and embedding is another trusted preservation method for tissue samples. Formalin-fixed paraffin-embedded (FFPE) biospecimens are immersed in a fixative of 10% formalin. Formalin immediately stops the biological and cellular activity within specimens, stopping the decay process right after fixative immersion. After 18–24 hours, fixed specimens are then dehydrated using ethanol and prepared for embedment. The tissue samples are then embedded in paraffin wax, making it easier for the specimens to be sliced and mounted on microscopic slides. 

FFPE tissue samples can be stored indefinitely in biobanks, hospitals, laboratories, or research centers. For quality assurance reasons, fixed and embedded specimens should be stored at 4℃ with limited light exposure. FFPE tissues are compatible with a variety of histological staining techniques, such as immunohistochemistry (IHC), allowing researchers to find and locate protein structures within the biospecimen. Fixing and embedding tissue samples preserves the cellular and tissue structure of specimens, which is essential for histopathological studies. If stored at room temperature, FFPE samples can be stored for an extended amount of time, making it possible to curate extensive archives of specimens that can be used for future analysis. The fixing and embedding process of FFPE specimens is also well-standardized across the board, leading to consistently pure samples, which is paramount for comparative research.

Other Short-Term Techniques

Apart from freezing and FFPE techniques, there are other shorter-term preservation methods for biospecimen storage. Hypothermic preservation, for example, slows down the chemical processes occurring in human tissues and protects refrigerated specimens from cold-induced injuries. Tissue samples are bathed in a cold storage solution, preserving them for no longer than 1 to 2 days in low temperatures. 

Depending on the type of tissue sample, researchers can also store specimens in a refrigerator with a temperature of 2–8℃. Biospecimens stored in a refrigerator will stay preserved for just a few days, so it’s important to utilize these samples quickly for research purposes.

3 Best Practices for Tissue Preservation

Biospecimen storage is an extremely important step of tissue procurement and preservation. Here are 3 best practices to implement when storing tissue samples:

  1. Label Tissue Samples: Label tissue samples with collection date, tissue type, and preservation technique. You can also include donor demographics such as age, gender, and ethnicity. Labeling biospecimens with as much information as possible reduces errors down the line and maintains traceability for future research needs.
  2. Avoid Contamination: Rapid processing is a top priority in tissue preservation. If you want to ensure quality control, minimize the time between human tissue collection, transportation, and preservation as much as possible. Make certain that tissue samples are being handled with care and adhering to ethical guidelines 100% of the time. Rapid processing prevents the risk of unnecessary tissue contamination. 
  3. Prevent Degradation: Consistently check the condition of the stored biospecimens, ensuring the preservation methods are effective. Monitor and log the biospecimen storage temperatures, preventing degradation and breakdown of structural integrity. 

Consistency is key when it comes to tissue preservation. If you prioritize labeling samples, rapid processing, and monitoring tissues day in and day out, stored biospecimens will stay in top-notch condition. 

Preserved Tissue Samples For Your Research Goals

Superior BioDiagnostics understands how important it is to obtain tissue samples that are preserved in top-tier facilities. We provide researchers, laboratories, medical facilities, and more with high-quality biospecimens. Our team’s #1 goal is to maintain each tissue sample’s original structural and molecular state, ensuring you get the purest biospecimens for your research needs. 

Our biobank carries thousands of FFPE tissue samples, including normal, malignant, and disease-state biospecimens. Superior BioDiagnostics collects 100% US-procured chemically fixed and embedded tissue samples from the following anatomical sites: breast, lung, brain, muscle, skin, and more. Contact our biorepository to order specimens in the form of blocks, slides, and sections for your analysis.