OF VITRIFICATION AND PGS

The ART sector is constantly evolving. Over a decade ago, Vitrification came to revolutionize the IVF; now it is time for the genetic techniques. How would its generalization affect the IVF world?

As we all know, the age of women has an effect on the quality of their oocytes; this circumstance might lead to the development of embryos with some sort of aneuploidy, which is accountable for the most part of implantation failures and spontaneous miscarriages. In this scenario, a genetic analysis is highly recommended.

Some studies suggest the use of PGD/PGS on women close to 40 years old, targeting bigger percentages of aneuploidy embryos. However, when the goal is to transfer, successfully, a single euploid embryo, the performance of these programs would become a commodity among patients, even if that means increasing the costs of a fertility treatment (Kang HJ et al., 2016).

The evolution of genetic diagnose techniques has been unstoppable since the early 90’s; an evolution that had a lot to do with the development of reliable Vitrification Methods. Thanks to this “conjunction”, the results of IVF cycles improved significantly, allowing the detection of multiple genetic anomalies from a single embryo biopsy, enabling the selection of embryos without aneuploidies (Treff NR et al., 2017).

In the last decade, Vitrification has become the standard method for cryopreservation; its appearance had a huge impact in the traditional assisted reproduction techniques, redefining procedures like the Embryo Transfer. Nowadays, the “popularity” of the frozen embryo tranfers (FET) is noticeably higher than the classic fresh embryo transfers (Geraedts J. et al., 2016). Many papers that compared the Implantation Rate and the Pregnancy Rate between FET and fresh cycles backed up this statement, demonstrating also that an endometrium free of gonadotropins side effects could be a better environment for an embryo implantation, thus the best alternative to traditional fresh cycles (Braga DP. et al., 2016).

In the near future, deferred embryo transfers will not be a “trend” but a common practice in all the IVF labs.

Can it happen the same with the genetic analysis techniques in conjunction with Vitrification? Would it go from “trend” to common practice?  There is no doubt that Embryo biopsy is an “entrance barrier” for genetic programs; it is hard and it requires highly qualified staff. Nevertheless, the “benefits” of PGS are too great to give up before trying, especially if you work with Blastocysts.

“Blastos” allow you to obtain more genetic material from the trophectoderm, minimizing the harm to the embryo and the chances for mosaicism. Normally this procedure involves vitrification, which is necessary to delay the embryo transfer until the results of the biopsy are available. Rodriguez Purata showed in his study that biopsied embryos following a FET, achieved better implantation and pregnancy rates than those following fresh transfers (Rodriguez Purata J. et al., 2016).

It is therefore clear that genetic diagnose techniques as PGD/PGS allow choosing embryos without any genetic alteration or aneuploidies, increasing the chances to obtain a healthy newborn. All it takes for the clinics to adopt and widely offer these techniques is:

  1. A highly specialized staff of embryologists. Their role becomes, if possible, more important. Embryo Biopsies and Vitrification are critical points that can compromise the success of the whole treatment.
  2. A reliable vitrification method. Embryo survival must be “granted” when you are facing so many vitrifications and re-vitrifications. Only the Cryotop® Method can offer reliable proof of outstanding results with biopsied blastocysts (Rodriguez Purata J. et al., 2016).

Kitazato, as the global leader in vitrification techniques, is committed  to provide the best and most reliable and successful solutions in the field of cryopreservation.

Bibliography:

Braga DP1, Setti AS2, Figueira RC3, Azevedo Mde C3, Iaconelli A Jr3, Lo Turco EG4, Borges E Jr5. Freeze-all, oocyte vitrification, or fresh embryo transfer? Lessons from an egg-sharing donation program. Fertil Steril. 2016 Sep 1;106(3):615-22.

Geraedts J, Sermon K. Preimplantation genetic screening 2.0: the theory. Mol Hum Reprod. 2016 Aug;22(8):839-44.

Kang HJ1, Melnick AP2, Stewart JD1, Xu K1, Rosenwaks Z1.Preimplantation genetic screening: who benefits? Fertil Steril. 2016 Sep 1;106(3):597-602

Rodriguez-Purata J1, Lee J2, Whitehouse M2, Duke M2, Grunfeld L2,3, Sandler B2,3, Copperman A2,3, Mukherjee T2,3. Reproductive outcome is optimized by genomic embryo screening, vitrification, and subsequent transfer into a prepared synchronous endometrium. J Assist Reprod Genet. 2016 Mar; 33(3):401-412

Treff NR1, Zimmerman RS2 .Advances in Preimplantation Genetic Testing for Monogenic Disease and Aneuploidy. Annu Rev Genomics Hum Genet. 2017 May 12.

Poster:

  1. Oliana1, C.F.L. Hickman1, D. Gwinnett1, T. Wilkinson1, A. Carby2, G. Trew3, S. Lavery3.Warming-Biopsy-PGS-Revitrification-Rewarm-ET: A viable strategy for patients who want to minimize the number of frozen cycles before becoming pregnant.