Cryopreservation tissue

The collection of plant tissue is quite different from animal tissue collection. The discussion of collection of plant and animal tissue by Dessauer et al.2S is detailed and helpful. However, the recommendations for procedures unique to plant tissue collection are somewhat misleading and outdated, especially when tropical collections are involved. Plant tissue can now be collected and transported as either fresh tissue (leaves and/or shoot cuttings) or preserved tissue the latter either as cryopreserved tissue (liquid nitrogen or dry ice) or as dried tissue (air-dried, herbarium-dried, lyophilized, or chemically dried). Ambient-temperature liquid chemical preservation techniques (such as those routinely done for herbarium plant specimens in the tropics) so far have been ineffective in maintaining adequate yields of high-quality DNA.15 It should be stressed again that the manner of collecting plant tissue is dictated by several other factors what macromolecule (DNA, RNA, or isozymes) will be examined, what type of nucleic acid extraction method will be used (or, more impor-... 

Finkle BJ, ZavolaME, Ulrich JM. Cryoprotective compounds in the viable freezing of plant tissues, in Cryopreservation of Plant Cells and Organs (Kartha KK, ed.), CRC Press, Boca Raton, FL, 1985, pp. 75-113. 

Takenouchi, T., Y. Iwamaru, M. Sato, T. Yokoyama, M. Shinagawa, and H. Kitani. 2007. Establishment and characterization of SV40 large T antigen-immortalized cell lines derived from fetal bovine brain tissues after prolonged cryopreservation. Cell Biolint 31(l) 57-64. 

Wolfinbarger, L. and Hu, J.-F., DMSO concentration in fresh cryopreserved porcine valved conduit tissue, Cryobiology, 31, 461, 1994. 

Expense materials for tissue typing and cryopreservation of HSC are not certificated in Ukraine. The methods of tissue typing are not compatible, different sets are used hence, creation of the united compatible register is impossible. 

Tissue lysate (or homogenates), post-mitochondrial supernatants and microsomes offer several practical advantages for the study of xenobiotic metabolism. The principal advantages are that the human tissues provide a complete system containing all the enzymes in ratios found in vivo, and tissue fractions are stable in relatively long-term storage. Within the different types of tissue fractions, microsomes provide an enrichment of the membrane-bound enzymes, and post-mitochondrial supernatants provide a means to study both membrane-bound and soluble enzymes. Tissue fractions are easily prepared from a variety of tissues including human liver and can be cryopreserved for several years. This allows detailed characterization of the tissue prior to use with xenobiotics of unknown routes of metabolism... 

Primary human hepatocytes in particular have not yet proven to be compatible with cryopreservation (Utesch et al., 1992), therefore studies must be performed when the tissue becomes available. Characterization of the enzyme composition of the tissue derived from an individual must be conducted in parallel with characterization of the unknown xenobiotic. This can lead to the devotion of considerable experimental effort to studies which, in the end, do not meet quality control criteria. Despite these limitations, human hepatocytes are uniquely suited for studies of cytochrome P450 regulation and also provide the only current system which maintains a balanced and physiological ratio of cofactors and individual Phase I and Phase II enzymes. 

Once it is possible to expand a clinically defined and safe cell lineage for transplant, it is also necessary to be able to store the viable cells for subsequent attempts or procedures. This can avoid further surgery on the same patient. This demands the development of crypreservation methods for cells and tissues, involving a tissue bank (blood, skin, bones, cornea, bone marrow, umbilical cord blood, etc.). Cryopreservation must be efficient for long periods of storage, since the frozen cells may be required years after the initial deposit. 

There has been a demand for the development of cryopreservation methods for plant cells to avoid the troublesome maintenance of tissue cultures and the danger of microbial contamination. The most successful method for cryopreservation of plant cells reported so far has been the freezing of callus cultures or shoot tips [36, 37]. As the system here enables us to obtain sufficient initial shoot materials, its potential practical application to cryopreservation is in progress. In addition, the system of adventitious shoot formation might be a promising tool to investigate relationship between morphogenesis (shoot formation) and alkaloid biosynthesis. 

Care must be taken not to overtrypsinize the cells when removing them from the tissue culture surface. The 2.2.15 cells are sticky and have a natural tendency to clump. Aggregated cells do not grow well and are difficult to count. The 2.2.15 cells also perform better in reseeding and cryopreservation procedures if they receive fresh medium 24 h before trypsinization. 

Technologies to improve these processes and to monitor tissue parameters for performance control and modeling will further help to develop applicable cryopreservation protocols. 

So far, our description of preservation has focused mostly on proteins or enzymes in solution. Less is known about the cryopreservation and lyophilization of entire cells or tissues, which is one of the ultimate objectives of our work. While many of the ideas or hypotheses described above in the context of proteins are also applicable to cells or tissue, the inherent complexity of such systems poses important, additional challenges. In particular, the role played by cell membranes must be taken into consideration. 

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