Successful pregnancy depends on precise molecular regulation of uterine physiology, especially during the menstrual cycle. Deregulated oxidative stress (OS), often influenced by inflammatory changes but also by environmental factors, represents a constant threat to this delicate balance. Oxidative stress induces a reciprocally regulated nuclear factor erythroid 2-related factor 2/peroxisome proliferator-activated receptor-gamma (Nrf2/PPARγ) pathway. However, increased PPARγ activity appears to be a double-edged sword in endometrial physiology. Activated PPARγ attenuates inflammation and attenuates OS to restore redox homeostasis. However, it also interferes with physiological processes during the menstrual cycle, such as hormonal signaling and angiogenesis. This review provides an elucidation of the molecular mechanisms that support the interplay between PPARγ and OS. Additionally, it offers fresh perspectives on the Nrf2/PPARγ pathway concerning endometrial receptivity and its potential implications for infertility.

Human papillomavirus (HPV)-associated lesions and malignancies exhibit alterations in the composition and functionality of the extracellular matrix (ECM) that represent the complex molecular pathways present between infection and disease. A total of 20 urine samples were used, including from 10 patients with cervical intraepithelial neoplasia grade 3 (CIN3) and 10 healthy controls to perform the label-free quantitative analysis using the nano-HPLC and ESI-MS ion trap mass analyzer and matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI-TOF/MS) fast screening. Among 476 identified/quantified proteins, 48 were significantly changed (log₂-fold change ≥1.0 or ≤−1.0, −log10 (bbinominal, p-value ≥ 1.3), of which were 40 proteins (down-regulated) and 8 proteins (up-regulated) in CIN3, in comparison to healthy controls. The biological function and key pathway enrichment of the gene set using gen set enrichment analysis (GSEA) were analyzed. The ECM-receptor interaction pathway (NES = −1.64, p = 0.026) was down-regulated by 13 proteins (HSPG2, COL6A1, COL6A3, SPP1, THBS1, TNC, DAG1, FN1, COMP, GP6, VTN, SDC1, and CD44; log₂ FC range from −0.03 to −1.48) for the CIN3 group in the KEGG database. The MALDI-TOF/MS screening showed the difference of protein profiles between the control and CIN3 groups, i.e., using the scatter plot with a well-separated shape, as well as effectively distinguishing both groups (control and CIN3) using genetic algorithms (GA) with cross-validation (51.56%) and recognition capability (95.0%). Decreased levels of ECM-receptor interaction proteins may cause disturbances in the interactions of cells with the ECM and play an important role in the development and progression of cervical cancer.

The increased interest in assisted reproduction through in vitro fertilization (IVF) leads to an urgent need to identify biomarkers that reliably highly predict the success of pregnancy. Despite advances in diagnostics, treatment, and IVF approaches, the 30% success rate of IVF seems insurmountable. Idiopathic infertility does not have any explanation for IVF failure especially when a patient is treated with a healthy competitive embryo capable of implantation and development. Since appropriate intercellular communication is essential after embryo implantation, the emergence of the investigation of embryonic secretome including short non-coding RNA (sncRNA) molecules is crucial. That’s why biomarker identification, sncRNAs secreted during the IVF process into the blastocyst’s cultivation medium, by the implementation of artificial intelligence opens the door to a better understanding of the bidirectional communication between embryonic cells and the endometrium and so the success of the IVF. This study presents a set of promising new sncRNAs which are revealed to predictively distinguish a high-quality embryo, suitable for an embryo transfer in the IVF process, from a low-quality embryo with 86% accuracy. The identified exact combination of miRNAs/piRNAs as a non-invasively obtained biomarker for quality embryo determination, increasing the likelihood of implantation and the success of pregnancy after an embryo transfer.

Infertility affects millions worldwide, and implantation failure remains a critical barrier in assisted reproduction. Endometrial receptivity, a fundamental prerequisite for successful implantation, involves precise regulation of extracellular matrix components, with hyaluronan (HA) being particularly significant due to its structural and signaling roles. This study evaluated the expression of genes involved in HA metabolism and regulation across different phases of the menstrual cycle, particularly emphasizing their role during the window of implantation in normal fertility and repeated in vitro fertilization failures. Analysis of publicly available transcriptomic datasets revealed distinct expression patterns of HA synthases (HAS2, HAS3), HA-degrading enzymes (HYAL2, CEMIP, CEMIP2), and HA receptors (CD44, RHAMM, layilin) in endometrium that dynamically change toward the receptive state. Notably, HAS enzymes and HA receptors were upregulated during the mid-secretory phase, whereas classical HA-degrading enzymes showed complex regulation, suggesting a balance between HA synthesis and degradation necessary for optimal endometrial function. In patients with repeated IVF failure, there was significant downregulation of key HA-related genes (HAS2, HAS3, CEMIP, CD44, versican, syndecans), implicating impaired HA metabolism in implantation failure. The results underscore the role of HA metabolism and HA receptors in establishing a receptive endometrial environment, highlighting HA and its associated pathways as potential therapeutic targets to enhance reproductive success rates. Further research is necessary to unravel the detailed molecular mechanisms of HA-mediated regulation and its translational implications for assisted reproduction technologies.

Objective: The aim of the study was to evaluate the predictive value of the human chorionic gonadotropin (hCG) concentration on the 14th and 16th post-ovulation day after embryo transfer/cryoembryo transfer as well as the dynamics of its increase with respect to the outcome of pregnancy. Materials and methods: In total, 130 embryo transfers and cryoembryo transfers in women aged 22 to 38 years who experienced a single embryo transfer or single cryoembryo transfer with confi rmed pregnancy (hCG level over 15 IU/l on 14th post-ovulation day – D14) were selected. The input parameters (hCG D14, hCG D16, hCG D16-D14, hCG D16/D14 and positivity of at least 2.5fold increase in hCG D16 compared to hCG D14) were evaluated by regression analysis in relation to the outcome parameters (bio chemical pregnancy, clinical pregnancy, clinical pregnancy terminated by abortion up to 12 weeks of gestation, clinical pregnancy terminated by childbirth). Results: Single concentrations of hCG D14 and D16, as well as the difference between these concentrations, were a statistically significant indicator of the prediction of biochemical pregnancy (P = 0.000215, P = 0.000227 and P = 0.000421). Contrary to expectations, the proportion of hCG D16 and D14 concentrations did not show statistical significance for either parameter, as well as the fulfilment of the condition of at least a 2.5fold increase in hCG D16 compared to D14. None of the studied input parameters was confirmed as a statistically significant marker for the prediction of miscarriage in the whole group of patients. However, in the group of confirmed clinical pregnancies, the serum concentration of hCG D16 (P = 0.0248) and the difference between concentrations D16 and D14 (P = 0.0185) were confirmed as a positive predictor of the progression of pregnancy until delivery. Conclusions: Single hCG concentrations are a good prognostic factor for predicting the outcome of pregnancy, but the determination of the cut-off limit is limited by inter-laboratory deviation as well as by timing of blood collection for hCG determination on the exact post-ovulatory day. The results of individual studies are therefore difficult to use in clinical practice. The dynamics of hCG concentrations appear to be a more reliable predictor of pregnancy outcome. In our cohort, we confirmed the statistical significance of the difference in hCG concentration between the 16th and 14th post-ovulation day not only for the prediction of bio chemical pregnancy, but also as a predictor of the progression of clinical pregnancy into childbirth. To determine the optimal values of this difference, it is necessary to evaluate a larger group of patients. Conversely, the statistical significance of the proportion of hCG concentrations between the 16th and 14th post-ovulation day was not confirmed. Key words: in vitro fertilisation – human chorionic gonadotrophin – embryo transfer – cryoembryo transfer – bio chemical pregnancy – hCG dynamics – ongoing pregnancy – childbirth after embryo transfer

Purpose: In vitro fertilization occurs in a controlled laboratory setting, where oocytes are fertilized by sperm, and the resulting embryos are cultured to the blastocyst stage before transfer to the uterus. The secreted/consumed substances by the embryo in the extracellular environment (secretome) contain a variety of molecules that may provide insights into embryo quality. This study presents new perspectives on the non-invasive and cost-effective assessment and evaluation of embryos during the IVF process, utilizing a spent embryo culture medium (SECM). Methods: The SECM was used from blastocysts prepared for a single blastocyst transfer and was analyzed in two groups—the SECM with successful (F) (n = 30) and unsuccessful (N) (n = 36) embryo implantation in the woman's uterus. Building on our previous next-generation sequencing results, we decided to validate the expression levels of specific miRNAs, particularly hsa-miR-16-5p and hsa-miR-92a-3p, to assess their potential to predict embryo implantation success. Results: Our results demonstrate different expression levels of miRNA molecules in the monitored groups, which could lead to their use in non-invasive analysis of the implantation potential of embryos in the IVF process. In this study, we employed a metabolomics approach using 3D fluorescence analysis of SECM to identify differences between the studied groups, F and N. Our preliminary results indicate a slightly increased metabolic activity in the group with unsuccessful embryo implantation group. Conclusions: This is our pilot study where we demonstrated the use of two approaches in analyzing the SECM to predict the implantation potential of embryos in the IVF process which promises further development.