Blastocyst transfer after aseptic vitrification of zygotes: an approach to overcome an impaired uterine environment

in Reproductive Biomedicine Online (2012), 25

In some IVF cycles, no fresh embryo transfer in the stimulated cycle is advisable. The cryopreservation of zygotes and the transfer of blastocysts in a cryo-embryo transfer is an option to circumvent an ... [more ▼]

In some IVF cycles, no fresh embryo transfer in the stimulated cycle is advisable. The cryopreservation of zygotes and the transfer of blastocysts in a cryo-embryo transfer is an option to circumvent an inadequate uterine environment due to risk of ovarian hyperstimulation syndrome, inappropriate endometrium build up, endometrial polyps or uterine myomas. For this strategy, highly secure and safe cryopreservation protocols are advisable. This study describes a protocol for aseptic vitrification of zygotes that results in high survival rates and minimizes the potential risk of contamination in liquid nitrogen during cooling and long-term storage. In mouse zygotes, there was no difference in efficiency as compared with a conventional open vitrification system. In IVF patients, aseptically vitrified zygotes showed no difference in blastocyst formation rate as compared with sibling zygotes kept in fresh culture. A clinical study comprising 173 cryo-cycles with a transfer of blastocysts originating from vitrified zygotes showed an ongoing pregnancy rate of 40.9%. The live birth rate per patient was 36.8%. A combination of good clinical results and increased safety conditions due to aseptic vitrification encourages the use of cryo-embryo transfer for patients with a suboptimal uterine environment in a fresh cycle. [less ▲]

Support fermé: une réalité clinique pour vitrifier en conditions aseptiques les ovocytes et embryons

in Gynécologie Obstétrique & Fertilité (2010), 38(9), 541-546

Vitrification with the use of ‘‘Open’’ carrier devices (Cryoloop, cryotop, cryoleaf, Vitriplug) which allowed the contact with liquid nitrogen has become a more popular way to achieve cooling rate ... [more ▼]

Vitrification with the use of ‘‘Open’’ carrier devices (Cryoloop, cryotop, cryoleaf, Vitriplug) which allowed the contact with liquid nitrogen has become a more popular way to achieve cooling rate superior to 20.000 °C/min. Even though the question of contamination with liquid nitrogen during ultra-rapid cooling and storage remain debatable with the use of ‘‘open’’ devices, it is important to revise the carrier system in a way, which minimizes the risk of contamination. According to the EU tissues and cells directive, it is advisable that the cooling and storage should be carried out in embryo carrier devices ensuring complete separation of the embryos from liquid nitrogen in a way, which minimizes the risk of contamination. The consequence of a reduction in the cooling rate resulting from the heat-insulating barrier of aseptic devices has to be counteracted by gradually increasing intracellular concentrations of cryoprotectants without inducing a toxic effect. We developed an aseptic vitrification method of vitrification for MII oocytes and embryos at different stage of development using the ‘‘VitriSafe’’ as ‘‘closed’’ carrier device. [less ▲]

Cryopreservation des embryons humains par vitrification.

in Gynécologie Obstétrique & Fertilité (2006), 34(9), 760-9

Vitrification is a cryopreservation strategy where cells are converted into a glass-like amorphous solid which is free of any crystalline structure. Such process is achieved by a combination of high ... [more ▼]

Vitrification is a cryopreservation strategy where cells are converted into a glass-like amorphous solid which is free of any crystalline structure. Such process is achieved by a combination of high concentration of cryoprotectant and an extremely high cooling rate. In the last years, survival rates of up to 80% after thawing and pregnancy rates of almost 30% could be achieved after transfer of vitrified embryos at the zygote, cleavage, morula and blastocyst stages. Also deliveries of healthy babies have been reported numerous times. To this day, a limited interest in this technique can be noted. The explanation may lye in the apprehension of many ART units regarding exposure of embryos to high concentrations of cryoprotectants and storage in non sterile conditions. The aim of the first part of this article, is to analyse if such fears are justified on the basis that vitrification mimics conditions already in use for many years in slow-cooling procedures where cells are plunged into liquid nitrogen at around -30 degrees C and secondly since storage of embryos are now possible in high aseptic conditions. In the second part, results on survival after thawing, pregnancy rates and baby take home rates of vitrified embryos will be presented and the problems associated with vitrification of blastocysts will be discussed. [less ▲]