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The ability to freeze blood and its constituents is very important to preserve them for a long time. However, freezing and thawing blood can cause damage to its components, resulting in reduced integrity and unreliable biochemical measurements.
This article provides the best practice methods for reducing the damage caused to blood products as a result of freezing and thawing.
Freezing Blood is Required for Medicine and Research
Usually, whole blood is donated and broken down into its constituent parts using a centrifuge. Whole blood contains four main components such as white blood cells, red blood cells, plasma, and platelets. Each individual component plays a specific role within the body and is used to treat specific conditions in patients. For instance, platelet concentrate can be used to treat people with a low platelet count or poor platelet function, which often arise in patients receiving chemotherapy.
Since fresh blood and its components can be stored only for a certain period of time, freezing blood products can help enable a steady supply of life-saving transfusions for patients, even in rural areas and other places which are hard to reach.
Freezing and thawing are two important operations in plasma fractionation. The fluid component of the blood — plasma — is mostly made up of water (up to 95% by volume) but also contains glucose, dissolved proteins, hormones, electrolytes, clotting factors, and respiratory gases. Freezing and thawing plasma helps in producing concentrated solutions of individual plasma components, such as clotting factors, for patient transfusion.
Animal and human blood is usually taken for diagnostic measurements, signifying the health of the individual the blood is drawn from. In life sciences research and clinical trials, blood samples are taken from individuals taking part in research or trials for analyses such as measuring metabolites or biomarkers present in the blood of the individual. Usually, relevant blood samples are frozen and stored in a central laboratory for additional retrospective studies and future analysis. Since blood serum is the preferred sample for various clinical assays, many samples are also stored in this way. Except for the clotting factors, blood serum has all the plasma components and prevents coagulant interference with clinical assays. Fresh serum and plasma are only stable for 3-5 days at ambient temperatures, but they can be stored frozen for 2-5 years for later analysis.
The Damage Caused by the Freezing and Thawing of Blood
Freezing and thawing blood products can reduce their integrity and therefore, the effectiveness of transfusion products is lowered and the reliability of biochemical measurements is limited.
For frozen cells, including white blood cells and red blood cells, thawing is stressful and can result in cell lysis. But, rapid freezing is even worse and leads to the formation of ice crystals in cells which push against the cell membranes, making the cells to burst.
While the formation of ice crystals can be prevented by slow cooling, this can promote an imbalance in osmotic pressure, which also causes cell rupture. Therefore, the rate of cooling must be carefully controlled to retain integrity and quality when freezing and thawing blood products.
Both serum and plasma do not contain cells, but the act of freezing and thawing can still damage them because they cause chemical changes to metabolites, proteins, DNA, and biomarkers. The formation of ice crystal alters the concentrations of proteins and salts in solutions, which can lead to denaturation of proteins and loss of their functional properties, lowering the clinical efficacy of blood. Moreover, for biochemical research, even small DNA damage caused by freezing and thawing can result in indecipherable sequencing data.
Minimizing Freeze/Thaw Damage
By minimizing the damage caused by freezing and thawing, it can be ensured that patients receive only the best possible transfusion products when undergoing therapy, thus enabling reliable biochemical measurements in the life sciences. Most of the problems caused by freezing and thawing blood samples can be prevented by following best practices and using a cryoprecipitate bath to carefully regulate the freezing and thawing process.
To prevent deterioration of blood components, they must be isolated and frozen as soon as possible. Different tubes are used when taking blood samples to increase the speed of isolation and stability of the required blood component. In addition, cryoprotectants can be added to prevent the formation of ice crystals and minimize the osmotic effects of freezing.
Repeated freezing and thawing cycles must be avoided when storing blood samples for later analysis. Separating blood samples into aliquots prior to freezing is considered to be a good practice because repeated freezing and thawing can be prevented whenever a new analysis is needed. In order to avoid partial thawing, the temperature should be monitored and maintained continuously.
Cryoprecipitate bath from PolyScience. Image credit: PolyScience
With cryoprecipitate baths, blood products and samples can be safely thawed which will offer the right flow and temperature conditions to reduce damage during thawing. PolyScience’s cryoprecipitate bath, with a temperature stability of ±0.1 °C and the ability to process 24 units of fresh blood at once, is perfect for thawing blood products.
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- Effect of Repeated Freezing and Thawing on Biomarker Stability in Plasma and Serum Samples — JE Lee, SY Kim, SY Shin, Osong Public Health and Research Perspectives, 2015
- Freeze-Thaw Cycles and Why We Shouldn’t Do It https://bitesizebio.com/19700/freeze-thaw-cycles-and-why-we-shouldnt-do-it/
- Effects of sample handling, processing, storage, and hemolysis on measurements of key energy metabolites in ovine blood — JD Morris, JM Fernandez, AM Chapa, LR Gentry, KE Thorn, TM Weick, Small Ruminant Research, 2002.
- Effects of Storage Temperature and Time on Clinical Biochemical Parameters from Rat Serum — C Cray, M Rodriguez, J Zaias, NH Altman, Journal of the American Association for Laboratory Animal Science, 2009.
- Biospecimen Sampling in Clinical Trials http://med.stanford.edu/content/dam/sm/sccr/documents/trainingsessions/Biospecimen%20Sampling%2017NOV2015%20Science%20Talk.pdf
- Stability studies of twenty-four analytes in human plasma and serum — BL Boyanton, KE Blick, Clinical Chemistry, 2002.
- PolyScience cryoprecipitate bath https://www.polyscience.com/specialty-product/cryoprecipitate-bath
PolyScience was started in 1963. They pioneered innovations ranging from the first zero-switching circulators to the first refrigeration systems for DNA amplification to an award-winning line of culinary products.
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