Cryoprotectants: the essential antifreezes to protect life in the frozen state. CryoLetters

University Department of Surgery, Royal Free and University College Medical School, London NW3 2QG, UK.
Cryo letters (Impact Factor: 1.14). 11/2004; 25(6):375-88.
Source: PubMed


In the fifty years since the establishment of the cryoprotective effect of glycerol, cell banking by cryopreservation has become routine in many areas of biotechnology and medicine. Cryoprotectant addition has become a rather mundane step within the overall protocol. However, for future advances in cryobiology and to meet new challenges in the clinical use of cryopreserved cells or tissues, it will be essential to have an understanding of the development and current status of the biological and chemical knowledge on cryoprotectants (CPA). This review was undertaken to outline the history of CPA use, the important properties of CPA in relation to freezing damage, and what can be learnt from natural freezing-tolerant organisms. The conflicting effects of protection and toxicity resulting from use of CPA are discussed, and the role of CPA in enhancing glassy states in the emerging field of vitrification are also set out.

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Available from: Barry J Fuller
    • "Hydroxy groups of sugars and sugar alcohols, e.g., glycerol, are thought to substitute for water in the hydration shells of membranes and macromolecules, thus stabilizing their conformation during dehydration and freezing-thawing events and decreasing membrane phase transition temperature (Anchordogue et al., 1987;Crowe et al., 1987Crowe et al., , 1990Hoekstra et al., 2001). In addition, some cryoprotectants can act as free radical scavengers and exhibit antioxidant activities (Benson, 2004;Fuller, 2004). Due to these and other potential protective properties, cryoprotectant mixtures are often used for cryopreserving plant materials that may be intolerant to severe dehydration, such as orchid protocorms, PLBs and meristematic tissues as explained in sections 5-7. "
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    ABSTRACT: Orchids (Orchidaceae) are one of the most diverse plant groups on the planet with over 25,000 species. For over a century, scientists and horticulturalists have been fascinated by their complex floral morphology, pollinator specificity and multiple ethnobotanical uses, including as food, flavourings, medicines, ornaments, and perfumes. These important traits have stimulated world-wide collection of orchid species, often for the commercial production of hybrids and leading to frequent overexploitation. Increasing human activities and global environmental changes are also accelerating the threat of orchid extinction in their natural habitats. In order to improve gene conservation strategies for these unique species, innovative developments of cryopreservation methodologies are urgently needed based on an appreciation of low temperature (cryo) stress tolerance, the stimulation of recovery growth of plant tissues in vitro and on the ‘omics’ characterization of the targeted cell system (biotechnology). The successful development and application of such cryobiotechnology now extends to nearly 100 species and commercial hybrids of orchids, underpinning future breeding and species conservation programmes. In this contribution, we provide an overview of the progress in cryobanking of a range of orchid tissues, including seeds, pollen, protocorms, protocorm-like bodies, apices excised from in vitro plants, cell suspensions, rhizomes and orchid fungal symbionts. We also highlight future research needs.
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    • "Sugar is one of the essential components of most semen extenders (Gadea, 2003; Bearden et al., 2004; Purdy, 2006) and honey is known to consist primarily sugars such as monosaccharides, disaccharides, oligosaccharides and polysaccharides (Bogdanov et al., 2008) that can act as a source of energy to support spermatozoa survival and motility during cryopreservation. Naturally, honey is also a highly concentrated product and has the potential hyperosmotic extracellular environment around sperm cells that enhances efflux of intracellular fluid thereby minimizing formation of ice crystals inside the sperm cytoplasm which has been linked to sperm damage during cryopreservation (Royere et al., 1996; Fuller 2004; Fakhrildin et al., 2014). This mechanism of protection gives honey the property of a non-permeable cryoprotectant. "

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    • "It should be noted that glycerol is easily digested, non-toxic and is recognized as safe by food and drug administration. At low temperatures , glycerol may serve as penetrating cryoprotectant that inhibits the growth of ice crystals (Fuller 2004). Due to its strong interactions with water in the plant system, some parts of water become unfreezable or bound. "
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    ABSTRACT: The effects of pulsed electric fields (PEF) and osmotic impregnation in glycerol solution on the amount of unfreezable water in apple were determined by means of low-temperature differential scanning calorimetry (DSC). The obtained data were compared with behaviour of pure water–glycerol solutions (sample WG). PEF treatment was applied using a near-rectangular monopolar generator with pulse duration of 100 μs at electric field strength of 800 V/cm. The osmotic impregnation of PEF-treated apple discs was done using water–glycerol (sample AWG) and apple juice–glycerol (sample AJG) osmotic solutions at different concentration of water or juice in glycerol, W = 30–100 wt%. The data evidenced that for the PEF-treated samples the glycerol was able to penetrate successfully inside apple tissue. The state diagrams for WG, AWG and AJG samples were rather similar. It was observed that free water existed only for moisture content above some minimum value. The unfreezable water content was the largest in AJG, followed by WG and AWG. The juice concentration in glycerol W ≈ 80 wt% was found to be optimal for preservation of the texture of PEF-treated samples.
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