Vitrification in human and domestic animal embryology work in progress /

According to the analysis of papers published in major international journals, rapidly increasing application of vitrification is one of the greatest achievements in domestic animal and especially human embryology during the first decade of our century. This review highlights factors supporting or hampering this progress, summarises results achieved with vitrification and outlines future tasks to fully exploit the benefits of this amazing approach that has changed or will change many aspects of laboratory (and also clinical) embryology. Supporting factors include the simplicity, cost efficiency and convincing success of vitrification compared with other approaches in all species and developmental stages in mammalian embryology, while causes that slow down the progress are mostly of human origin: inadequate tools and solutions, superficial teaching, improper application and unjustified concerns resulting in legal restrictions. Elimination of these hindrances seems to be a slower process and more demanding task than meeting the biological challenge. A key element of future progress will be to pass the pioneer age, establish a consensus regarding biosafety requirements, outline the indispensable features of a standard approach and design fully-automated vitrification machines executing all phases of the procedure, including equilibration, cooling, warming and dilution steps

Vitrification in human and domestic animal embryology : work in progress

According to the analysis of papers published in major international journals, rapidly increasing application of vitrification is one of the greatest achievements in domestic animal and especially human embryology during the first decade of our century. This review highlights factors supporting or hampering this progress, summarises results achieved with vitrification and outlines future tasks to fully exploit the benefits of this amazing approach that has changed or will change many aspects of laboratory (and also clinical) embryology. Supporting factors include the simplicity, cost efficiency and convincing success of vitrification compared with other approaches in all species and developmental stages in mammalian embryology, while causes that slow down the progress are mostly of human origin: inadequate tools and solutions, superficial teaching, improper application and unjustified concerns resulting in legal restrictions. Elimination of these hindrances seems to be a slower process and more demanding task than meeting the biological challenge. A key element of future progress will be to pass the pioneer age, establish a consensus regarding biosafety requirements, outline the indispensable features of a standard approach and design fully-automated vitrification machines executing all phases of the procedure, including equilibration, cooling, warming and dilution steps

Risk of contamination of germplasm during cryopreservation and cryobanking in IVF units

Cryopreservation of sperm, embryos and, more recently, oocytes plays an important and increasing role in assisted reproduction, due to improvements of old, and introduction of new technologies. In parallel, concerns are increasing about the technical and biological safety of these procedures. However, published data regarding the confirmed or theoretical hazards of these procedures are sparse and sometimes contradictory. The purpose of this review will summarize data and opinions about one of the most disputed risks, the potential hazard of contamination and disease transmission through cryopreservation. Special attention is concentrated on the weak points of the technology including open vitrification systems, sterilization of liquid nitrogen and safety of commonly used storage tanks including straws and cryovials. Suggestions are also made for practical measures to avoid these dangers while preserving the benefits and perspectives of new cryopreservation technologies

Vitrification of human mature oocytes in clinical practice

Oocyte cryopreservation has long been the focus of unsuccessful efforts to perfect its clinical application. Lately, vitrification has been shown to provide high degrees of success by different research groups. This review attempts to address the efficiency of oocyte vitrification in clinical practice through an analysis of reports of IVF cycles in which embryo transfers have been conducted with vitrified metaphase-II human oocytes

Contamination of single-straw carrier for vitrification

To the Editor: We read with interest the recent article by Criado et al. (1) (http://www.fertstert.org/article/S0015-0282(10)02987-0/abstract) regarding the assessment of contamination of a single-straw ultravitrification closed carrier (Ultravit). They observed no contamination in any microdrops of medium contained in the closed devices, where as the bacteria they used for forced contamination of liquid nitrogen (LN2) were present in 45% of open carriers’ strip (Cryotop)

Open versus closed systems for vitrification of human oocytes and embryos

Vitrification is now the dominant approach for cryopreservation of human oocytes and embryos; however, serious disagreement persists, particularly about biosafety issues. Techniques are categorized as either ‘open’ or ‘closed’ according to occurrence of direct contact between the medium and liquid nitrogen during cryopreservation. Advocates of closed systems emphasize the potential danger of disease transmission mediated through liquid nitrogen, and praise the safety of their approach; those who use the open systems refer to the lack of evidence of disease transmission and regard their systems as more consistent and efficient. The purpose of this review is to clarify whether open and closed systems are really open and closed; if closed systems are safe and free of any danger of contamination; if closed systems are equally efficient as open ones for cryopreservation of human embryos and oocytes by considering overall outcome; and finally, if ethical and legal concerns are sound when risks and benefits are considered in a broader sense. On the basis of these answers, implementation of rational measures to lower the theoretical dangerof disease transmission are proposed while maintaining the achievements in cryopreservation that have contributed substantially tothe advancement in assisted reproduction techniques during the past decade

New culture devices in ART

During the past decades, improvements in culture of preimplantation embryos have contributed substantially in the success of human assisted reproductive techniques. However, most efforts were focused on optimization of media and gas components, while the established physical conditions and applied devices have remained essentially unchanged. Very recently, however, intensive research has been started to provide a more appropriate environment for the embryos and to replace the rather primitive and inappropriate devices with more sophisticated and practical instruments. Success has been reported with simple or sophisticated tools (microwells or microchannels) that allow accumulation of autocrine factors and establishment of a proper microenvironment for embryos cultured individually or in groups. The microchannel system may also offer certain level of automation and increased standardization of culture parameters. Continuous monitoring of individual embryos by optical or biochemical methods may help to determine the optimal day of transfer, and selection of the embryo with highest developmental competence for transfer. This advancement may eventually lead to adjustment of the culture environment to each individual embryo according to its actual needs. Connection of these techniques to additional radical approaches as automated ICSI or an ultimate assisted hatching with full removal of the zona pellucida after or even before fertilization may result in devices with high reliability and consistency, to increase the overall efficiency and decrease the work-intensity, and to eliminate the existing technological gap between laboratory embryology work and most other fields of biomedical sciences

Cells under pressure : how sublethal hydrostatic pressure stress treatment increases gametes' and embryos' performance?

The principal approach in in vitro embryo culture and manipulation has been a defensive one: procedures aim to satisfy passively the supposed or real physiological needs of gametes and embryos. Similarly, during cryopreservation the aim is to cause minimal damage to cells whilst attempting to obtain the highest achievable cell survival. However, carefully chosen and precisely controlled sublethal stress treatment of cells has been described to improve embryos’ and gametes’ performance, and, as a consequence, subsequent morphological survival, fertilisation, in vitro development, pregnancy and farrowing rates improved considerably compared with untreated controls. This review summarises studies that open up a new approach: instead of – and besides – trying to passively reduce the harm to cells during in vitro manipulations and culture, procedures may also prepare the cells themselves to ward off or reduce the damage by turning up the cells’ own, inner capacities