Metabolic signature of follicular fluid in infertility-related diseases: a narrative review.

Metabolomics offers new methods to identify biomarkers for oocyte and embryo quality, and for a better understanding of the physiopathology of infertility. This review investigated the latest findings regarding metabolome-derived biomarkers in follicular fluid of women with the most common types of infertility, and the potential impact on reproductive medicine outcomes. PubMed was searched for publications on metabolomics and human follicular fluid, and key biomarkers, kinetics and relationships with infertility diseases were identified. A reduced concentration of glucose and increased concentrations of lactate and pyruvate were found in follicular fluid of patients with endometriosis and diminished ovarian reserve, and the opposite was found in patients with polycystic ovary syndrome. These signatures may lead to the hypothesis of changed metabolite concentrations in patients with endometriosis and diminished ovarian reserve, and a metabolic pathway alteration with decreased aerobic glycolysis in patients with polycystic ovary syndrome. However, the pattern found in patients with endometriosis and low responders may also be expected in follicular fluid of fertile women. Larger studies are needed to confirm the results. An international database may help to highlight follicular fluid biomarkers in order to improve the selection of cryopreserved oocytes, and to enrich culture medium to restore normal metabolism and improve reproductive treatment outcomes.

Mechanical Characterization of Murine Oocytes by Atomic Force Microscopy.

The quality of murine and human oocytes correlates to their mechanical properties, which are tightly regulated to reach the blastocyst stage after fertilization. Oocytes are nonadherent spherical cells with a diameter over 80 µm. Their mechanical properties have been studied in our lab and others using the micropipette aspiration technique, particularly to obtain the oocyte cortical tension. Micropipette aspiration is affordable but has a low throughput and induces cell-scale deformation. Here we present a step-by-step protocol to characterize the mechanical properties of oocytes using atomic force microscopy (AFM), which is minimally invasive and has a much higher throughput. We used electron microscopy grids to immobilize oocytes. This allowed us to obtain local and reproducible measurements of the cortical tension of murine oocytes during their meiotic divisions. Cortical tension values obtained by AFM are in agreement with the ones previously obtained by micropipette aspiration. Our protocol could help characterize the biophysical properties of oocytes or other types of large nonadherent samples in fundamental and medical research.

ICSI using testicular spermatozoa after failure of ICSI with ejaculated spermatozoa could be a good choice: A propensity score-matched cohort study.

BACKGROUND: Ejaculated spermatozoa are considered to possess a higher fertilisation potential than testicular spermatozoa. In selected cases, the use of testicular spermatozoa from non-azoospermic infertile men resulted in a higher implantation and pregnancy rate than the use of ejaculated spermatozoa. OBJECTIVE: The primary objective was to compare the live birth rate and cumulative live birth rate between couples with failed intracytoplasmic sperm injection procedure using ejaculated spermatozoa who subsequently had an intracytoplasmic sperm injection cycle with testicular spermatozoa and those who subsequently had an intracytoplasmic sperm injection cycle with ejaculated spermatozoa. The secondary objective was to determine the indications for the use of testicular spermatozoa after intracytoplasmic sperm injection failure with ejaculated spermatozoa. MATERIALS AND METHODS: A retrospective study of matched couples using propensity score matching analysis was performed. After an intracytoplasmic sperm injection failure (cycle_1), intracytoplasmic sperm injection with either ejaculated spermatozoa (ejaculated sperm group), or testicular spermatozoa (testicular sperm group), was performed (cycle_2). The matching was on intracytoplasmic sperm injection performed in cycle_1 according to spermatozoa used (testicular or ejaculated) in cycle_2. Logistic regression was used to evaluate the influence of sperm origin on cumulative live birth rate. Univariate analysis on parameters of cycle_1 was used to identify the prognostic factors to propose an intracytoplasmic sperm injection with testicular spermatozoa in case of cycle_1 failure. The study outcomes were live birth rate and cumulative live birth rate. RESULTS: Among the 6034 couples available, 63 were selected to constitute the testicular sperm group and 63 were selected by propensity score matching to constitute the ejaculated sperm group. After matching, the DNA fragmentation index was higher in the testicular sperm group (13.43% ± 9.65% vs. 8.93% ± 4.47%, p = 0.013); no significant difference was observed for the fertilisation rate, the number of obtained embryos, blastulation rate and frozen embryo rate. In cycle_2, the live birth rate was higher in the testicular group (22.2% vs. 0.0%, p < 0.001), as was the cumulative live birth rate (25.4% vs. 6.3%, p = 0.065). The prognostic factors identified for the proposal of intracytoplasmic sperm injection procedure with testicular spermatozoa after intracytoplasmic sperm injection failure with ejaculated spermatozoa were: teratozoospermia, cryptozoospermia and high DNA fragmentation index. DISCUSSION: According to the present study and current knowledge, the use of testicular spermatozoa after failed intracytoplasmic sperm injection procedure in non-azoospermic men could be proposed instead of sperm donation in case of high sperm DNA fragmentation index, cryptozoospermia and teratozoospermia. A good oocyte response to ovarian stimulation during the previous assisted reproductive technology attempt will increase the chance of success. Although the main limitation of the current study is its retrospective nature, the use of the propensity score matching to perform causal inference study increases its reliability. CONCLUSION: The present study supports that the use of testicular spermatozoa outside the classical indication of azoospermia is a good option when the indication is well established. However, before proposing a testicular biopsy, an improvement in sperm characteristics should be considered by treating the causes of sperm alteration.