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Understanding Reproductive Health and Infertility: Molecular and Genetic Insights

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Biology".

Deadline for manuscript submissions: 20 July 2025 | Viewed by 4732

Special Issue Editor

Special Issue Information

Dear Colleagues,

Reproductive health is a very complex issue that cannot be understood without applying deep molecular and genetic insights. In brief, the success or failure of reproductive health is conditioned by the following three factors:
1. Sperm quality;
2. Oocyte quality;
3. Uterine receptivity.

1. Sperm quality
Basic parameters of sperm quality include sperm count, motility, and morphology and can be assessed through spermogram and spemocytogram values. However, there are other parameters that are not included in this basic evaluation, in particular sperm DNA damage (fragmentation). This parameter can be associated with genetic abnormalities (aneuploidies or deletions), but it can also occur without any genetic damage, due to different kinds of environmental factors. Thus, the examination of sperm DNA integrity should be included as an additional test for all cases of infertility.

2. Oocyte quality
In addition to different types of chromosomal abnormalities that can be detected by karyotype screening in blood cells, there are many other possible genetic and molecular factors that may cause female infertility. First, one important factor is the female age. Aging females accumulate mutations in mitochondrial DNA, leading to limited available energy for healthy embryo development. However, there is another important factor that damages human oocyte quality more than that of other mammalian species, e.g., the mouse. In fact, human preimplantation embryos are programmed to initiate embryonic genome expression at the eight-cell stage later than that of mice and most other rodents (the two-cell stage). To compensate for this characteristic, human oocytes need to accumulate a significant amount of stored maternal mRNA to cover the early embryos’ metabolic needs. The stock of stored maternal mRNA tends to decrease with increasing maternal age. This can partly explain the fact that aging rodent females are more likely to procreate as compared to women. Some therapeutical interventions, such as injections of cytoplasm from young oocyte donors or transfers of patients’ chromosomes to enucleated donor oocytes, were proposed to resolve this condition. However, these techniques are not permitted by law in many countries.

3. Uterine receptivity
The ability of the uterus to promote implantation of healthy embryos depends on two essential factors. First, the adequate secretion of progesterone by the ovarian corpus luteum, which remains in the ovary after ovulation or artificial oocyte extraction. Second, the correct ability of the uterus to respond to progesterone. In order to distinguish between these two conditions, the first useful approach is to determine the serum concentration of progesterone during the luteal phase. If the level of progesterone is low, substitution therapy is recommended. On the other hand, if progesterone level is normal, a search for other factors is needed. Later, at the end of the first trimester, there is another menace. In normal conditions, the production of progesterone is shifted from the corpus luteum to the placenta. If this luteoplacental shift does not work correctly, an abrupt fall in progesterone levels can cause pregnancy loss.

All researchers engaged in any of the above topics are invited to contribute to this Special Issue.

Dr. Jan Tesarik
Guest Editor

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Keywords

  • sperm quality
  • oocyte quality
  • uterine receptivity

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Published Papers (4 papers)

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Research

14 pages, 2489 KiB  
Article
Bacteria-Mediated Anomalous Rho GTPase Activation Alters Sperm Structure and Provokes Premature Capacitation Events: A Possible Mechanism of Infertility
by Bárbara Rivera, Claudia Aroca, Braian González, Neftalí Guzmán, Pablo Letelier, Pamela Uribe, Miguel Fornés, Juana Valentina Villegas and Rodrigo Boguen
Int. J. Mol. Sci. 2025, 26(8), 3783; https://doi.org/10.3390/ijms26083783 - 17 Apr 2025
Viewed by 231
Abstract
Male infertility is often linked to sperm quality issues; however, the mechanisms behind these alterations remain unclear in certain contexts. This study investigates the impact of anomalous Rho GTPase activation—a process triggered by bacterial toxins—on human sperm structure and function. Human spermatozoa were [...] Read more.
Male infertility is often linked to sperm quality issues; however, the mechanisms behind these alterations remain unclear in certain contexts. This study investigates the impact of anomalous Rho GTPase activation—a process triggered by bacterial toxins—on human sperm structure and function. Human spermatozoa were exposed in vitro to a Rho GTPase activator derived from Escherichia coli under both capacitating and non-capacitating conditions. The results showed increased RhoA GTPase activity in non-capacitating conditions, without affecting viability or mitochondrial membrane potential. However, progressive motility decreased across both conditions, while non-progressive motility and acrosome reaction rates increased. Additionally, intracellular calcium levels rose exclusively in non-capacitating conditions. Structural analysis revealed an increase in abnormal sperm morphology, particularly vacuoles in the sperm head. These findings highlight that anomalous Rho GTPase activation disrupts essential processes like motility and capacitation, which are crucial for successful fertilization. This study provides novel insights into how bacterial infections may induce sperm damage, proposing that Rho GTPase activity could serve as a biomarker for evaluating sperm quality in cases of infertility linked to urogenital infections. Understanding these mechanisms may improve diagnostic and therapeutic approaches for male infertility associated with bacterial pathogens. Human spermatozoa were exposed in vitro to a Rho GTPase activator derived from Escherichia coli under both capacitating and non-capacitating conditions. Full article
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20 pages, 1829 KiB  
Article
Exploring the Role of Lower Genital Tract Microbiota and Cervical–Endometrial Immune Metabolome in Unknown Genesis of Recurrent Pregnancy Loss
by Sergey A. Mikhalev, Mark A. Kurtser, Victor E. Radzinsky, Mekan R. Orazov, Narasimha M. Beeraka and Lyudmila M. Mikhaleva
Int. J. Mol. Sci. 2025, 26(3), 1326; https://doi.org/10.3390/ijms26031326 - 4 Feb 2025
Viewed by 1062
Abstract
Recurrent pregnancy loss (RPL) of unknown genesis is a complex condition with multifactorial origins, including genetic, hormonal, and immunological factors. However, the specific mechanisms underlying endocervical cell proliferation disorders in women with RPL remain inadequately understood, particularly concerning the role of microbiota and [...] Read more.
Recurrent pregnancy loss (RPL) of unknown genesis is a complex condition with multifactorial origins, including genetic, hormonal, and immunological factors. However, the specific mechanisms underlying endocervical cell proliferation disorders in women with RPL remain inadequately understood, particularly concerning the role of microbiota and viral infections. The aim of this study was to investigate the mechanisms of endocervical cell proliferation disorders in women with RPL of unknown genesis by examining microbiota, human papillomavirus (HPV) typing, and the expression levels of key molecular biological markers, including p16/Ki-67, BCL-2, miR-145, and miR-34a. A prospective observational comparative study was executed on women with RPL and healthy pregnant controls with full ethical approval. Samples were collected for HPV typing and immunocytochemical analysis to evaluate the expression of p16, Ki-67, BCL-2, and the anti-oncogenic microRNAs (miR-145 and miR-34a). The expression of mRNA for the progesterone receptor (PGR-A) was also assessed, alongside local immune status markers, including proinflammatory T-lymphocytes (Th17/Th1) and regulatory CD4+ Tregs. Overexpression of p16, Ki-67, and BCL-2 was observed in 52.5% of women with RPL who had an ASC-US/LSIL cytogram, with the average double expression of p16/Ki-67 being three times higher than in the healthy pregnant group. A significant decrease in PGR-A mRNA expression in the endocervix of women with RPL was noted, accompanied by a dysregulated local immune status characterized by an increased prevalence of Th17/Th1 cells and a reduction in regulatory CD4+ Tregs. Additionally, the expression of miR-145 and miR-34a in the endocervix and endometrium of women with RPL significantly differed from the physiological pregnancy group, particularly in the context of high-risk HPV infection. The findings describe that disorders of endocervical cell proliferation in women with RPL of unknown genesis are associated with overexpression of specific molecular markers, impaired immune regulation, and altered microRNA profiles. These alterations may contribute to the pathophysiology of RPL, highlighting the need for further research into targeted interventions that could improve reproductive outcomes in affected individuals. Full article
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18 pages, 3360 KiB  
Article
Positive Effect of Elevated Thawing Rate for Cryopreservation of Human Ovarian Tissue: Transcriptomic Analysis of Fresh and Cryopreserved Cells
by Qingduo Kong, Plamen Todorov, Cheng Pei, Evgenia Isachenko, Gohar Rahimi, Nina Mallmann-Gottschalk and Volodimir Isachenko
Int. J. Mol. Sci. 2024, 25(24), 13747; https://doi.org/10.3390/ijms252413747 - 23 Dec 2024
Viewed by 1222
Abstract
Ovarian tissue cryopreservation has been gradually applied. It is essential to elucidate the differences between cryopreserved and fresh ovarian tissue and to refine cryopreservation protocols for improved outcomes. To explore the transcriptomic differences between fresh ovarian tissue and tissue cryopreserved with an elevated [...] Read more.
Ovarian tissue cryopreservation has been gradually applied. It is essential to elucidate the differences between cryopreserved and fresh ovarian tissue and to refine cryopreservation protocols for improved outcomes. To explore the transcriptomic differences between fresh ovarian tissue and tissue cryopreserved with an elevated thawing rate. Ovarian tissue samples were collected and cryopreserved (frozen and thawed) following RNA sequencing and histological evaluation. Three groups were formed: fresh tissue (Group 1), frozen tissue after quick thawing at 100 °C (Group 2), and frozen tissue after slow thawing at 37 °C (Group 3). KEGG analysis showed that in comparison with Group 1, DEGs in Group 2 were mainly enriched in the cortisol synthesis and ovarian steroidogenesis pathways, and DEGs in the cells of Group 3 were mainly enriched in the ovarian steroidogenesis pathway. GO analysis showed that compared to cells of Group 2, DEGs in Group 3 were primarily enriched in the SRP-dependent co-translational protein targeting pathway and co-translational protein targeting to the membrane. The results were formulated with a minimal difference in the histological evaluation of cells after quick and slow thawed tissue. Cryopreservation of ovarian tissue by the described method does not decrease follicle production but downregulates the ovarian steroidogenesis pathway, reducing estrogen and progesterone secretion. The quick thawing of ovarian tissue increases the proliferation and apoptosis pathways of cells. Full article
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17 pages, 4320 KiB  
Article
Plasma Lipidomics Reveals Lipid Signatures of Early Pregnancy in Mares
by Tharangani R. W. Perera, Elizabeth G. Bromfield, Zamira Gibb, Brett Nixon, Alecia R. Sheridan, Thusitha Rupasinghe, David A. Skerrett-Byrne and Aleona Swegen
Int. J. Mol. Sci. 2024, 25(20), 11073; https://doi.org/10.3390/ijms252011073 - 15 Oct 2024
Cited by 3 | Viewed by 1351
Abstract
Understanding the systemic biochemistry of early pregnancy in the mare is essential for developing new diagnostics and identifying causes for pregnancy loss. This study aimed to elucidate the dynamic lipidomic changes occurring during the initial stages of equine pregnancy, with a specific focus [...] Read more.
Understanding the systemic biochemistry of early pregnancy in the mare is essential for developing new diagnostics and identifying causes for pregnancy loss. This study aimed to elucidate the dynamic lipidomic changes occurring during the initial stages of equine pregnancy, with a specific focus on days 7 and 14 post-ovulation. By analysing and comparing the plasma lipid profiles of pregnant and non-pregnant mares, the objective of this study was to identify potential biomarkers for pregnancy and gain insights into the biochemical adaptations essential for supporting maternal recognition of pregnancy and early embryonic development. Employing discovery lipidomics, we analysed plasma samples from pregnant and non-pregnant mares on days 7 and 14 post-conception using the SCIEX ZenoTOF 7600 system. This high-resolution mass spectrometry approach enabled us to comprehensively profile and compare the lipidomes across these critical early gestational timepoints. Our analysis revealed significant lipidomic alterations between pregnant and non-pregnant mares and between days 7 and 14 of pregnancy. Key findings include the upregulation of bile acids, sphingomyelins, phosphatidylinositols, and triglycerides in pregnant mares. These changes suggest enhanced lipid synthesis and mobilization, likely associated with the embryo’s nutritional requirements and the establishment of embryo–maternal interactions. There were significant differences in lipid metabolism between pregnant and non-pregnant mares, with a notable increase in the sterol lipid BA 24:1;O5 in pregnant mares as early as day 7 of gestation, suggesting it as a sensitive biomarker for early pregnancy detection. Notably, the transition from day 7 to day 14 in pregnant mares is characterized by a shift towards lipids indicative of membrane biosynthesis, signalling activity, and preparation for implantation. The study demonstrates the profound lipidomic shifts that occur in early equine pregnancy, highlighting the critical role of lipid metabolism in supporting embryonic development. These findings provide valuable insights into the metabolic adaptations during these period and potential biomarkers for early pregnancy detection in mares. Full article
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