The study and selection of embryos before transfer is a key step for the success of
infertility treatments in assisted reproduction. The current techniques applied are
called preimplantation genetic testing of aneuploidies (PGT-A) and are highly sensitive
and specific, although they require the retrieval of four to six cells (a biopsy) from an
embryo at an early stage of development (blastocyst stage).
Nowadays, the alternatives for embryo selection given to young and healthy women or to
couples that do not want to undergo PGT-A are based on studying the morphology and
development of the embryos. Unfortunately, these are not reliable methods to know if the
embryos have the right number of chromosomes.
A new method called non-invasive PGT-A (niPGT-A) analyses the genetic material released
by the embryo to the culture medium (Spent Blastocyst Media, SBM) where the embryo grows
in the IVF lab. This genetic material allows for identification of the chromosome number
of the embryo. In a previous pilot study, the results of the analysis of the culture
media were concordant with the results of the embryo biopsy in 85% of cases.
The current study will analyze the genetic constitution of the SBM and correlate the
results of the same analysis on the inner cell mass (ICM) and trophectoderm (TE) cells
taken in different locations (multifocal biopsy) to improve our understanding of the
mechanisms and origin of the embryo genetic content released to the culture medium during
its preimplantational development.
Once this prospective and observational study is approved by the competent Research
Ethics Committee, the recruitment and selection of patients will follow. Every potential
participant will be asked to sign the study informed consent only after finishing their
assisted reproductive treatment.
To comply with the design of this pilot study, a total number of 200 blastocysts donated
to research after IVF/ICSI or PGT-A cycles has been estimated to generate enough results.
After warming, blastocysts will be subjected to multifocal biopsies of TE, ICM isolation
and collection of the SBM. This part of the study will be performed in the collaborating
centers. Samples will be shipped to Igenomix Spain for the genetic research and further
data analysis.
The expected duration of the study is 18 months. Embryos will be included in the
different participating centers for an estimated period of 9 months. Participants
involvement in the study is just linked to the moment of the consent form signature for
the embryo donation. This study will not imply any modification of a scheduled IVF/ICSI
or PGT-A cycles nor extra visits to the recruiting centers.