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Caracterização dos danos celulares em gametas femininos e embriões após criopreservação / Characterization of cellular damage in female gametes and embryos after cryopreservation

Carvalho, Adeline de Andrade; Faustino, Luciana Rocha; Castro, Simone Vieira; Figueiredo, José Ricardo; Rodrigues, Ana Paula Ribeiro.
Acta sci. vet. (Impr.); 40(3): Pub. 1046, 2012. ilus
Artigo em Português | VETINDEX | ID: biblio-1373606

Resumo

Background: Cryopreservation is a biotech successfully employed in female gametes and embryos. This technique is of great importance for propagation of genetic material from animals with high-value livestock as well as to preserve the fertility of women undergoing cancer treatments. However, low temperatures can result in damage to different cellular compartments and organelles. This damage culminates in reduced viability, since they affect cell metabolism. Review: Cryopreservation consists of maintenance of biological material at low temperatures, in which chemical reactions are ceased, however, allowing the cells to preserve their viability. However, the decrease of temperature and subsequent warming may result in cellular damage. These damages occur in the cell membrane, cytoplasmic organelles and the cell nucleus. It is believed that the first cell structure undergoing cryoinjury is the plasma membrane, responsible for maintaining homeostasis within the cell, and the loss of plasma membrane during the reduction temperature reported the main damage. The membrane damage due to cryopreservation appears to correlate with the reduction of thermal energy at low temperatures, thus limiting the movement of molecules through the phospholipids of lipid bilayer. Cryopreservation also alters the morphology, structure and cellular distribution of lipid droplets, reducing the survival of oocytes and embryos. The physical state changes, besides changing physicochemical properties of intracellular lipid may also result in damage to lipids associated with the cellular cytoskeleton. The interaction between cell lipid phase and components of cytoskeleton is complex and hardening of these lipids can cause deformation and disruption of cytoskeleton with consequent negative effect on cell survival and development. The disruption of cytoskeleton can also be intrinsic to change in dehydration and cellular form that follow the cryopreservation process. Among the cellular organelles, mitochondria are sensitive to cryopreservation procedures, since the formation of intracellular ice crystals considered one of the most relevant cryoinjury, leading to damage to the mitochondrial cristae and matrix. Another important organelle undergoes damage as result of cryopreservation is the endoplasmic reticulum, which change in morphology has been described after vitrification of embryos. It is also known that cryopreservation may result in fragmentation of DNA even in the absence of deformation of the cellular morphology, and that these changes can lead to delay in the development or cell death. In addition to the direct damage to double-stranded DNA, cryopreservation may trigger chromosomal abnormalities, these the aneuploidy is the most frequent and seems to compromise the developmental competence of oocytes in addition to being indicated as the main factor for the low achieve of live births. Conclusion: Cryopreservation is an important alternative for the preservation of gametes and embryos, however, the cells are subjected to unfavorable conditions that can compromise cell recovery after thawing/warming. The main cause of reduction in survival oocytes and embryos after cryopreservation appear to be related to damage in different cellular compartments and structures, which are essential for maintaining cell metabolism. Thus, it is observed the need to achieve cryopreservation protocols capable of maintaining the integrity of different cellular components.
Biblioteca responsável: BR68.1