Lay summary

The endometrium lines the inner wall of the uterus and is the site where the fertilised egg implants to establish pregnancy. Disorders of the endometrium cause infertility and chronic pain. Techniques to measure genetic activity, termed transcriptomics, have been applied to better understand the endometrium in health and disease. We collated all studies, totalling 74, that describe transcriptomics of endometrial samples from non-pregnant women and compared study designs and genetic activity measurements. The studies generally looked at small numbers of samples, with most focussing on fertility rather than endometrial disorders. Study designs were variable, comparing women under different definitions of fertility and disease, and under different treatments. Additionally, key participant factors such as BMI were mostly not reported. These and other limitations produced genetic activity measurements that were inconsistent, especially in cases of infertility and endometrial disorders. Addressing these limitations could improve how transcriptomic approaches are used to advance endometrial health.

Graphical abstract

Abstract

Infertility affects millions of couples worldwide. Oxidative stress (OS) causes peroxidation of lipids and damage to spermatozoa, thus, reducing the quality of seminal parameters. In addition, the differences in the levels of antioxidants and reactive oxygen species (ROS) caused by intrinsic and extrinsic variables linked to lifestyle, diet, genetics, and OS also contribute to male infertility. High levels of ROS result in sperm damage of sperm parameters due to lipid peroxidation and oxidation of proteins. Other significant causes of ROS include changes in sex hormone levels, sperm DNA damage, including mutations, and immature spermatozoa. Treating the root causes of OS, by changing one’s lifestyle, as well as antioxidant therapy, may be helpful strategies to fight OS-related infertility. However, the determination of male infertility induced by OS is currently a challenge in the field of reproductive health research. This review intends to describe the role of oxidative stress on male infertility and the current understanding of its management.

Lay summary

The inability to conceive affects many couples globally. Oxidative stress refers to imbalances between different oxygen species which can lead to male fertility problems by damaging sperm and semen. Oxidative stress may be caused by several factors, including diets high in fats, sugars and processed foods, lifestyle (including smoking, alcohol consumption and having a sedentary lifestyle), and genetics. Treatment that focuses on the root cause may help combat male infertility. However, there is currently no consensus on the best way to treat male fertility problems, particularly those associated with oxidative stress. This paper describes the role of oxidative stress on male infertility and discusses the current techniques employed in treating male fertility issues.

Graphical abstract

Abstract

Sperm cryopreservation is a valuable tool for the long-term preservation of male fertility. Thus, determining the optimal technique for isolating spermatozoa post-thaw is vital to ensure recovery of the highest quality spermatozoa with minimal iatrogenic damage. This not only enhances the chances of successful conception but also reduces the risk of genetic damage in the embryo. To address this issue, human semen samples were cryopreserved using a slow freezing protocol and Quinn's Advantage™ Sperm Freeze medium. The samples were subsequently thawed and subjected to three types of sperm isolation procedures: direct swim-up, density gradient centrifugation, and electrophoretic separation using the Felix™ device. Cryopreservation led to the anticipated loss of sperm motility and vitality in association with increases in lipid peroxidation and DNA damage. Following sperm selection, all three isolation techniques resulted in an increase in sperm motility which was particularly evident with the swim-up and Felix™ procedures. The latter also significantly improved sperm vitality. There were no differences between sperm separation techniques with respect to morphology, and mitochondrial reactive oxygen species generation remained essentially unchanged when cell vitality was taken into account. By contrast, major differences were observed in DNA integrity and lipid aldehyde formation, where Felix™ isolated cells exhibiting significantly less DNA damage than the other isolation procedures as well as lower levels of 4-hydroxynonenal formation. Electrophoretic sperm isolation, therefore, offers significant advantages over alternative separation strategies, in terms of the quality of the gametes isolated and the time taken to achieve the isolation.

Lay Summary

Long-term storage of sperm is vital to assisted reproductive technology because it permits the preservation of fertility that might be compromised as a result of factors such as chemotherapy or vasectomy. This goal can be achieved via cryopreservation – the freezing of cells to −196°C. When the sperm are subsequently required for conception, they must be carefully separated from the cryopreservation medium in a manner that maximizes the chances of successful conception and minimizes the risk of genetic defects in the offspring. In this paper, three isolation techniques were compared for their ability to separate ideal sperm from semen and media following cryopreservation. It was found that cryopreservation led to lower levels of motility and vitality and created higher levels of DNA and cell membrane damage. Of the three techniques compared, only cells separated on the basis of their size and electric charge (electrophoretic isolation) exhibited significantly lower levels of DNA fragmentation.

Lay summary

Recurrent pregnancy loss is considered as two or more consecutive pregnancy losses. Fetal birth defects are thoroughly associated with chromosomal (thread-like structures containing packaged genetic material) abnormalities, which are the underlying causes of pregnancy loss. The evaluation of chromosomal abnormalities is required to diagnose pregnancy loss to improve the prognosis of future pregnancies. The largest proportion of chromosomal abnormalities was observed in the fetal tissue that remains in the uterus after pregnancy. We analyzed 300 retained fetal tissue samples and implicated different methods to recognize the structural abnormalities in the chromosomes. Moreover, simultaneously detect the expression of thousands of genes from fetal tissue. A clinical indication and their association of chromosomal abnormalities were obtained in 38% of cases with assorted fetal ultrasound defects in multiple pregnancy losses and two samples with a variety of unknown clinical indications. It revealed that chromosomal alteration in fetal birth defects is responsible for multiple pregnancy losses.

Graphical abstract

Abstract

Patients with chronic pelvic pain (CPP) may experience pain exacerbations requiring hospital admissions. Due to the effects of backlogged elective surgeries and outpatient gynaecology appointments resulting from the COVID-19 pandemic, we hypothesised that there would be an increased number of women admitted with CPP flares. We conducted a retrospective review of all acute gynaecology admissions at the Royal Infirmary of Edinburgh from July to December 2018 (pre-COVID) and 2021 (post-COVID lockdown). We collected information on the proportion of emergency admissions due to CPP, inpatient investigations and subsequent management. Average total indicative hospital inpatient costs for women with CPP were calculated using NHS National Cost Collection data guidance. There was no significant difference in the number of emergency admissions due to pelvic pain before (153/507) and after (160/461) the COVID-19 pandemic. As high as 33 and 31% had a background history of CPP, respectively. Across both timepoints, investigations in women with CPP had low diagnostic yield: <25% had abnormal imaging findings and 0% had positive vaginal swab cultures. Women with CPP received significantly more inpatient morphine, pain team reviews and were more likely to be discharged with strong opioids. Total yearly inpatient costs were £170,104 and £179,156 in 2018 and 2021, respectively. Overall, emergency admission rates for managing CPP flares was similar before and after the COVID-19 pandemic. Inpatient resource use for women with CPP remains high, investigations have low diagnostic yield and frequent instigation of opiates on discharge may risk dependence. Improved community care of CPP is needed to reduce emergency gynaecology resource utilisation.

Lay summary

Existing treatments for chronic pelvic pain (CPP) and endometriosis focus on surgery or hormone medication, but these are often ineffective or associated with unacceptable side-effects. As a result, women continue to experience chronic pain and often have ‘flares’ of worsening pain that may lead to hospital admission. The COVID-19 pandemic resulted in backlogged gynaecology clinics and surgeries. The aim of this study was to compare the management of emergency pelvic pain admissions for women with CPP before and after COVID-19. We also aimed to better understand their in-hospital management and estimate their hospital length of stay costs. We did not find an increase in CPP patients admitted for pelvic pain flares after the COVID-19 lockdown. Women with CPP often undergo multiple hospital tests and are often prescribed with strong pain medications which can cause long-term problems. Efforts are needed to improve long-term pain management for women with CPP.

Lay summary

Development of the early embryo depends upon regulation by chemical signals produced by the uterus. One of these signals is a protein called colony-stimulating factor 2 (CSF2) that can affect the development of embryos in culture. To test whether CSF2 also regulates the embryo in the uterus, where development ordinarily occurs, we evaluated development in the uterus of embryos in which the receptor for CSF2 was disrupted. Embryos without the receptor gene were less likely to develop to the typical stage of development than control embryos and experienced some differences in the expression of specific genes. We conclude that CSF2 regulates embryonic development in the uterus.

Lay summary

Ovarian follicles (the fluid-filled sacs that contain the eggs) develop within 2 or 3 waves during the human menstrual cycle. Typically, only one follicle in each cycle releases an egg during ovulation. The rest of the follicles grow then regress. In this study, we characterized differences in the growth, regression, and associated hormone production between follicles that ovulated and those that did not, developing from different waves within and between menstrual cycles. Differences regarding follicle growth patterns and hormone concentrations were found when comparing different waves and whether a follicle ovulated. Results from this study improve our understanding of the processes underlying follicular growth and ovulation, which in turn may assist in improving fertility and birth control treatments.

Lay summary

The corpus luteum is a part of the ovary responsible for producing the critical pregnancy hormone, progesterone. To fulfil this function, the corpus luteum requires an extensive blood vessel network. Here, we investigated whether an important growth factor known to act on the ovary, insulin like growth factor (IGF) 1, critically regulates the formation of this blood vessel network and progesterone production. Cells from the corpus luteum were cultured with combinations of IGF1, a closely related hormone IGF2 and a chemical which stops both IGF1 and IGF2 from working. Afterwards, we measured the size and pattern of blood vessel networks, the production of progesterone and whether cells increased in number. We found adding IGF1 had limited effects, however stopping IGF1 from working had a very negative impact on both progesterone and on the formation of the blood vessel network. This suggests that cells from the corpus luteum were producing IGF1 and that IGF1/2 are critical for both blood vessel growth and hormone production.

Graphical abstract

Abstract

Endometriosis is a common yet under-recognised chronic inflammatory disease, affecting 176 million women, trans and gender diverse people globally. The National Endometriosis Clinical and Scientific Trials (NECST) Registry is a new clinical registry collecting and tracking diagnostic and treatment data and patient-reported outcomes on people with endometriosis. The registry is a research priority action item from the 2018 National Action Plan for Endometriosis and aims to provide large-scale, national and longitudinal population-based data on endometriosis. Working groups (consisting of patients with endometriosis, clinicians and researchers) developing the NECST Registry data dictionary and data collection platform started in 2019. Our data dictionary was developed based on existing and validated questionnaires, tools, meta-data and data cubes – World Endometriosis Research Foundation Endometriosis Phenome and Biobanking Harmonisation Project, endometriosis CORE outcomes set, patient-reported outcome measures, the International Statistical Classification of Diseases-10th Revision Australian Modification diagnosis codes and Australian Government datasets: Australian Institute for Health and Welfare (for sociodemographic data), Medicare Benefits Schedule (for medical procedures) and the Pharmaceutical Benefits Scheme (for medical therapies). The resulting NECST Registry is an online, secure cloud-based database, prospectively collecting minimum core clinical and health data across eight patient and clinician modules and longitudinal data tracking disease life course. The NECST Registry has ethics approval (HREC/62508/MonH-2020) and is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12622000987763).

Graphical Abstract

Abstract

The transition of maternal to zygotic gene expression regulation is critical for human preimplantation embryo development. In recent years, single-cell RNA sequencing (scRNA-seq) had been applied to detect the factors that regulate human oocyte maturation and early embryo development. Here, the evaluation of transcriptomes in single blastomere from the embryo collected from patients by scRNA-seq was performed. There were 20 blastomeres biopsied from 8-cell embryos of seven patients who received more than two ART cycles due to low embryo competence. Meanwhile, ten cells were collected from 8-cell embryos of four patients who received ART treatment due to male or tubal factors. The blastomeres were then evaluated using the previously established scRNA-seq method to determine the associations between their gene expression and developmental competence. The total number of genes detected in 8-cell embryos that failed to form blastocyst including maternal and zygotic mRNAs was reduced. There were 324 differently expressed genes detected among the 8-cell embryos including 65 genes that were significantly suppressed in the 8-cell embryos that failed to form blastocyst. Further analysis found these 8-cell embryos arrested at the cleavage stage due to the dysfunction of the cell cycle, DNA transcription activity, histone methylation, and cell division-related genes such as SMCO-1, ZNF271P,ZNF679, ASF1b, BEX3, DPPA2, and ORC4. The alterations of gene expression detected in human 8-cell embryos are tightly associated with its developmental competence and could be used as targets to enhance embryo development or parameters to predict the embryo’s development outcomes.

Lay summary

Many females are suffering infertility due to the failure of embryonic development at early stages due to unknown causes. At the very beginning of human embryo development, the embryos start to express its own genes, which should be achieved at 8-cell stage. In current research, we isolated one cell from 8-cell embryos and detected the gene expression at single-cell level. Then the remaining cells of these embryos were cultured to form blastocyst. Meanwhile, the data was analyzed according to the outcomes of embryo development. We detected 324 differently expressed genes between the 8-cell embryos that succeeded and failed to form blastocyst. Our research showed the association between the gene expression and the developmental competence of 8-cell embryos. The findings could be used to predict the embryo quality and potential therapy target to improve the efficiency of assisted reproductive techniques.