Electrospun mats and films of polyvinyl alcohol (PVA) hydrogel are produced for drug delivery. To provide mechanical consistency to the gel a reinforcement by nanoclays is introduced in the polymer matrix. Four different suspensions of nanoparticles in the polymer solution are prepared in an adequate solvent. These suspensions are subjected to an electrospinning process to produce the nanofiber mat, while films are produced by casting. The influence of the process parameters over the nanofibers microstructure is analyzed by scanning electron microscopy (SEM). The effectiveness of nanoclay encapsulation in the nanocomposites is tested by a thermogravimetric analysis. A crosslinking reaction in solution is carried out to prevent the dissolution of the nanocomposites in aqueous media. A model protein (bovine serum albumin, BSA) is absorbed in the nanocomposites to characterize the release kinetics in phosphate-buffered saline (PBS).

The human endometrium is receptive to the embryo for a specific period of time known as the window of implantation (WOI). During this period, the endometrium shows a specific gene expression profile suitable for endometrial function evaluation. ER Map is a molecular tool able to accurately predict endometrial receptivity status by transcriptomic analysis. In this retrospective study, including 2256 subfertile patients undergoing ART treatment, the clinical value of precise WOI determination is studied in detail. Results obtained when single embryo transfers (sET) were scheduled either within the WOI timeframe as established by ER Map, or deviating from this WOI, are assessed and compared. Data obtained showed that 34.18% (771/2256) of patients had a displaced WOI. Analysis of ART outcomes showed significantly higher pregnancy rates in transfers scheduled within the WOI predicted compared to transfers that deviated more than 12h from this WOI (44.35% vs 23.08%, p < 0.001). The deviation from the WOI had also an impact on the progression of pregnancy, with a significant increase in pregnancy loss (~ twofold) observed in transfers that deviated more than 12h from the WOI predicted. These results indicate that the precise determination of the WOI and personalised embryo transfer can significantly improve clinical outcomes.

Spermatozoa motility is a key parameter during the fertilization process. In this context, spermatozoa tyrosine protein phosphorylation and an appropriate cytoskeleton α-tubulin distribution are some of the most important physiological events involved in motility. However, the relationship between these two biomarkers remains poorly defined. Here, we characterized simultaneously by immunocytochemistry the α-tubulin (TUBA4A) distribution and the tyrosine phosphorylation at flagellum before capacitation, during different capacitation times (1 and 4 hr), and after acrosome reaction induction in human spermatozoa. We found that the absence of spermatozoa phosphorylation in tyrosine residues positively and significantly correlated (p < 0.05) with the terminal piece α-tubulin flagellar distribution in all physiological conditions. Conversely, we observed a positive significant correlation (p < 0.01) between phosphorylated spermatozoa and continuous α-tubulin distribution in spermatozoa flagellum, independently of the physiological condition. Similarly, the subpopulation of spermatozoa with tyrosine phosphorylated and continuous α-tubulin increases with longer capacitation times and after the acrosome reaction induction. Overall, these findings provide novel insights into the post-transcriptional physiological events associated to α-tubulin and the tyrosine phosphorylation during fertilization, which present potential implications for the improvement of spermatozoa selection methods.

Study question How does the presence of specific pathogenic or health-promoting microbial species in the endometrium relate to female fertility in assisted reproduction treatments (ART)? Summary answer Detection of endometrial pathogens using MicroBioMap® is associated with poor ART outcomes, whereas sterile endometria show the highest pregnancy and live birth rates. What is known already Vaginal eubiosis is characterised by low microbial diversity and dominance of Lactobacillus, which displays bioregulatory functions and prevents the growth of pathogenic microorganisms. Vaginal dysbiosis is directly linked to infertility and poor pregnancy outcomes. However, the endometrial microbiota composition and its role in fertility are more controversial. Robust reports show that chronic endometritis (CE) is highly prevalent among infertile patients, whose outcomes improve after antibiotic treatment. However, the role of Lactobacillus in this compartment, whether it also displays bioregulatory functions, or if it is essential and beneficial for women undergoing ART, is still unclear. Study design, size, duration This is a case-control retrospective study analysing the endometrial microbiota in the window of implantation (WOI) and the ART outcomes of 456 women undergoing IVF cycles in egg donation regimes with/without PGT-A (177 and 163 respectively), or using their own eggs in cycles with/without PGT-A (91 and 25 respectively), between March 2016 and April 2021 in IVF-Life Alicante (Spain). ART results after single embryo transfer (sET) of patients with different endometrial microbiota profiles were compared. Participants/materials, setting, methods Presence of 18 microbial CE pathogens and 4 Lactobacillus species was determined by high-throughput qPCR (MicroBioMap®) in 456 endometrial samples obtained during the WOI (determined by ER Map® receptivity test) of a hormone replacement therapy cycle. Clinical outcomes (clinical pregnancy, CP; live birth, LB) of sETs performed during the WOI (guided by ER Map®) were compared in relation to the endometrial microbiota profile. In PGT-A cycles, embryo ploidy was determined by NGS (VeriSeq-MiSeq) before sET. Main results and the role of chance According to the microbial profile detected by MicroBioMap®, patients were categorised as i) Lactobacillus only (L, n = 199), ii) Pathogens only (P, n = 56), iii) Lactobacillus + pathogens (L+P, n = 59) or iv) Undetected (U, n = 142). Absence of endometrial microorganisms was significantly associated to ART success. U-patients showed significantly higher CP (64.2% vs 50.8%, Fisheŕs exact p=0.046) and LB rates (52.9% vs 37.2%, p=0.03) after euploid sET than patients with microorganisms. These differences were more pronounced in patients receiving donor eggs (CP 70.2% vs 50.8%, p=0.026; LB 59.5% vs 40.2%, p=0.046). Presence of Lactobacillus in isolation in the endometrium showed a detrimental effect compared to U-environments. A trend towards statistical significance was detected, with L-patients showing lower LB rates compared to U-patients after euploid sET (38.8% vs 52.9%; p = 0.084). Detection of endometrial pathogens significantly reduced ART success rates. P-patients had significantly lower CP rates (64.2% vs 41.2%, p=0.038) after euploid sET than U-patients, and significantly lower CP (70.2% vs 36%, p=0.006) and LB rates (59.5% vs 21.7%, p=0.004) if receiving donor eggs. Interestingly, Lactobacillus dominance in pathogen-positive patients seemed to improve outcomes after euploid sET compared to pathogen-dominated patients (CP 56.7% vs 42.2%; LB 41.7% vs 31%). Limitations, reasons for caution This is a retrospective study. Randomised-control trials, non-selection studies and/or other investigations including antimicrobial treatments are needed to confirm these results and the extent of any clinical benefits. Endometrial biopsies were obtained transcervically. Although utmost care was taken, risk of contamination from the lower genital tract cannot be completely excluded. Wider implications of the findings Our results suggest that sterile endometria provide the best conditions for embryo implantation and pregnancy. Lactobacillus presence in endometrium might not be essential for pregnancy, and could even be detrimental if found in isolation. Presence of Lactobacillus as a bioregulator might only be beneficial if other pathogens co-colonise the tissue. Trial registration number Not applicable