Human Embryo Cryopreservation Clinical Trial
Official title:
Randomized Comparison to Freeze Human Embryos by Either Vitrification or Slow Freezing Protocols
This randomized study compares three different freezing methods to store human in vitro fertilization (IVF) embryos: vitrification with two commercial kits or slow freezing. After information, all patients undergoing IVF treatment can be included in the study. If qualified, embryos at different developmental stages will be allocated between the three methods. At the end of the first year survival and developmental rates, and implantation and pregnancy rates will be analyzed in order to determine the best method.
Despite all the advances achieved in vitro fertilized treatments, it is known that the
chances of implantation for fertilised in vitro embryo remain limited, at around 20%.
Cryopreservation of supernumerary embryos produced during IVF cycles provides an opportunity
for patients to increase the number of transfers per oocyte harvest cycle, increasing then
their chances of conception.
The freezing technique may involve different media and methods, which lead to different
survival and developmental rates after thawing.
Vitrification is a new freezing method, which consists in exposing cells to high
concentrations of cryoprotectants and then cooling them ultra-rapidly; this induces an
increase in viscosity which favours the formation of a vitreous state without any ice
crystals formation. This method contrasts with the slow freezing method (currently
employed), which is based on exposure to very low concentrations of cryoprotectants combined
with long cooling times and associated with a higher risk of ice crystal formation.
Both methods can reduce cell survival and embryo ability to develop, either by the high
concentrations of cryoprotectants in case of vitrification, or by ice crystals formation in
case of slow freezing. The advantages of vitrification in embryology may be considerable
because embryos seem more sensitive to ice crystal formation than to cyroportectant
concentration; consequently, the elimination of office crystal injury may increase their
survival chances. Additionally in the case of vitrification, the time required for
equilibration and cooling is considerably reduced as well as the need for expensive
equipment such as programmable machine is eliminated.
At present, vitrification and slow freezing are used for the cryopreservation of oocytes and
embryos at all stages of development. Encouraging results have been obtained with
vitrification, but no study has randomly compared in one study, the two protocols and
cryoprotectors. The purpose of this clinic randomised study is to compare three treatments:
traditional slow freezing method currently employed (control group) and two different
commercial vitrification methods (experimental groups) to assess the efficacy that this
technique may involve.
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Allocation: Randomized, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment