Periodic Reporting for period 1 - CERVINO (Can human embryo-released extracellular vesicles govern endometrial receptivity and inform on vanguard embryo diagnostics and fertility therapeutics?)
Reporting period: 2018-07-02 to 2020-07-01
Infertility is defined as the inability of a couple to achieve pregnancy within one year, affecting approximately 10% of European couples. More than half of these couples rely on in vitro fertilisation (IVF) treatments, the majority of which do not result in a live birth, foremost as a result of poor embryo attachment to the womb lining leading to implantation failure. Embryos with abnormal chromosomal constitution, so-called aneuploid embryos, are accountable for approximately 50% of all recurrent implantation failures after IVF in women >35 years old. Preimplantation Genetic Testing for aneuploidy (PGT-A) is an add-on treatment proposed to IVF couples with advanced maternal age and/or those who repeatedly fail to achieve implantation. PGT-A is an early form of prenatal genetic diagnosis where aneuploid embryos are identified and only normal (euploid) embryos are selected for transfer into the womb in order to increase implantation probability. Although the patient access to PGT-A is rising, the technology itself is highly controversial; it requires an invasive biopsy of the embryo cells, which evidently decreases embryo quality. At the same time, the long-term safety of embryo biopsy in humans has not yet been evaluated. Thus, the development of non-invasive methods to screen out aneuploid embryos is paramount. However, since the other half of all implantation failures is attributed to unexplained causes, it is also critical to understand what biological mechanisms promote successful attachment of embryos to the womb lining.
Importance: PGT-A is an integral part of IVF procedures and increasing number of clinics perform embryo biopsy to all embryos regardless of indication only to ensure a euploid embryo is transferred to the womb, which hypothetically should decrease the time that a couple becomes a parent. PGT-A add-on is extremely costly and doubles the overall cost of conventional IVF due to the expertise required to perform embryo biopsy and the collateral costs like embryo freezing. Moreover, embryo biopsy has not been evaluated for long-term impacts on the offspring and it does not guarantee success as even in the case when a healthy embryo is transferred to the womb, it can still be rejected. Hence, less invasive and cheaper therapeutic options to diagnose embryos are in high demand and will make a tremendous impact on IVF practice. Finally, understanding why the womb rejects healthy embryos will help to better manage couples suffering for recurrent implantation failure.
Objectives: Our research project aimed a) to discover non-invasive biomarkers of embryo aneuploidy by studying the compounds that embryos secrete while growing in culture and b) describe a biological mechanism by which aneuploid embryos may stimulate a rejection response in the womb lining by exploring the feedback of womb cells to the internalisation of the aneuploid embryo-secreted compounds.
Importance: PGT-A is an integral part of IVF procedures and increasing number of clinics perform embryo biopsy to all embryos regardless of indication only to ensure a euploid embryo is transferred to the womb, which hypothetically should decrease the time that a couple becomes a parent. PGT-A add-on is extremely costly and doubles the overall cost of conventional IVF due to the expertise required to perform embryo biopsy and the collateral costs like embryo freezing. Moreover, embryo biopsy has not been evaluated for long-term impacts on the offspring and it does not guarantee success as even in the case when a healthy embryo is transferred to the womb, it can still be rejected. Hence, less invasive and cheaper therapeutic options to diagnose embryos are in high demand and will make a tremendous impact on IVF practice. Finally, understanding why the womb rejects healthy embryos will help to better manage couples suffering for recurrent implantation failure.
Objectives: Our research project aimed a) to discover non-invasive biomarkers of embryo aneuploidy by studying the compounds that embryos secrete while growing in culture and b) describe a biological mechanism by which aneuploid embryos may stimulate a rejection response in the womb lining by exploring the feedback of womb cells to the internalisation of the aneuploid embryo-secreted compounds.
CERVINO achieved the aims in line with the DoA. Hence, we discovered non-invasive biomarkers of embryo aneuploidy and described one of the possible biological mechanisms by which aneuploid embryos may stimulate a rejection response in the womb lining by exploring the feedback of womb cells to the internalisation of the aneuploid embryo-secreted compounds. Briefly, we found that aneuploid embryos packed four RNA fragments into their secreted EVs in significantly higher abundance than the respective EVs from euploid embryos (PPM1J, LINC00561, ANKRD34C and TMED10). These RNAs should be further explored and are envisaged to offer an exceptional ground for the development of novel non-invasive embryo PGT-A methods. We also found that when endometrial cells internalised aneuploid embryo-secreted EVs, they over-synthesised a critical compound (MUC1) that should otherwise be removed from the site of embryo attachment for successful implantation to occur. Therefore it is possible that aneuploid embryos are rejected via a mechanism whereby EVs deliver a ‘rejection package’ to the womb, which in turn produces a compound not compatible with embryo attachment. This theory should be further consolidated.
Overall, our cutting-edge work has advanced the state of the art and potentiates clinical innovation in the development of non-invasive methodology to diagnose aneuploid embryos and discovery of novel therapeutic targets to manage implantation failure. Future efforts to validate these findings will help bring more live births sooner in IVF practice. Parts of these findings have been presented in scientific conferences and institutional congresses. The final results and conclusions of the project will be presented during the largest conference (ESHRE - European Society of Human Reproduction and Embryology) in the field of human reproduction with an oral presentation on 30th June 2021. The aforementioned conference amounts 10.000 delegates across the world and this year's virtual meeting is believed to achieve a greater outreach. Hence, the 'Embryology session' where the researcher will present her work, is considered to be the greatest opportunity to reach all professionals working in the field of PGT and implantation. In addition, the results will be made available to the scientific community through publication, which is already drafted, and a big data repository, where the data will be uploaded as per publication submission requirements. The repository will make the raw data available to other scientists, who will be able to reanalyse the data to answer their own research questions and inspire their research. Once the open access publication is available, it will be shared on the researcher's Twitter account, which is followed by the majority of Twitter active Reproductive Health professionals.