Differential Granulosa Cell Transcriptome Profiling as a Predictive Tool of Ongoing Pregnancy

Fertility problems are increasingly common in industrialized countries. It is estimated that 15-20% of couples of reproductive age have problems conceiving children naturally and the use of assisted reproductive treatment accounts for 1-3% of annual births. Among the causes of infertility, the female factor is responsible for approximately 40% of cases. The growing problem of infertility and the decline in the birth rate in Spain make absolutely necessary the improvement of assisted reproductive technology (ART). Actually, one of the main problems of ART is the election of the oocyte, as there is no method to select the best embryos for subsequent transfer. The average number of oocytes obtained from one woman in each cycle is 10-11, so the finding of a (some) biomarker(s) would have a great impact at a social and economic level and would commensurately reduce the economic cost of each cycle. Novel embryo assessment strategies are currently being developed and can be used alone or in combination with morphologic criteria. These include non-invasive methodologies as artificial intelligence using morphokinetic databases and the OMICS, like transcriptomic, proteomic and metabolomic. Among others, the transcriptome of the cumulus cells is a potentially valuable non-invasive biomarker. Indeed, it is already known that granulosa cells play a crucial role in the regulation of female fertility. The bi-directional communication between the oocyte and the surrounding cumulus cells is essential for the maturation of a developmentally competent oocyte, ovulation and fertilization, processes which are necessary for initiating and sustaining embryo development. Our work hypothesis is that the cumulus cell transcriptome would be directly related and give an essential information about oocyte maturation and fertilization ability.

Unfortunately, even though several studies on granulosa cell transcriptome analysis have been performed, the obtained data are still inconclusive. The main reason for this should be found in the study design which, in most cases, are performed in a small number of patients and presented a heterogeneous population.

Among others, there are great variations in the patients' age and physical characteristics, type of treatment, diagnosis, hormonal levels and endometrial receptivity. The main objective of this project is to find new unknown biomarker(s) of ongoing pregnancy by analyzing the whole transcriptome of the two granulosa cell layers surrounding the oocytes (cumulus cells and corona radiata). Specifically, the study aims to find a biomarker of oocyte maturity, of fertilization, of embryo quality, of euploid embryos, of pregnancy, early miscarriage or ongoing pregnancy, and finally, to find a correlation between these biomarkers and the morphokinetic of the embryos. An additional advantage of our project is the use of material that is obtained at the time of transvaginal ultrasound-guided oocyte retrieval but that is considered a waste and is usually discarded in Assisted Reproduction Centers. Therefore, the analysis of these cells does not suppose any change or bother for the women, in relation to the treatments of assisted reproduction.