Reproduction

Handyside, Alan H

doi: 10.1530/rep-20-0412pmid: N/A

S Nagpal, Taniya; F Mottola, Michelle

doi: 10.1530/rep-20-0337pmid: 32805707

According to The Developmental Origins of Health and Disease theory, the intrauterine environment of the developing fetus may impact later life physiology, including susceptibility to chronic disease conditions. Maternal exposures during pregnancy can affect the intrauterine environment and result in fetal programming for chronic diseases through changes in the structure or function of specific organs. Negative maternal exposures, such as poor nutrition intake, have been shown to increase the risk for later life chronic diseases. On the contrary, healthful behaviors, such as physical activity, may have a positive and protective effect against chronic disease risk. This narrative review summarizes literature to discuss the potential preventative role prenatal physical activity may have on prevalent chronic diseases: obesity, type 2 diabetes, and cardiovascular disease. We describe the natural physiological response to pregnancy that may increase the risk for complications and consequently later life disease for both mother and baby. We then present evidence highlighting the role prenatal exercise may have in preventing pregnancy complications and downstream chronic disease development, as well as proposing potential mechanisms that may explain the protective maternal and fetal physiological response to exercise. As the prevalence of these non-communicable diseases increase globally, intervening during pregnancy with an effective exercise intervention may be the key to preventing chronic disease risk in more than one generation.

Rubio, Carmen; Rodrigo, Lorena; Simón, Carlos

doi: 10.1530/rep-20-0022pmid: N/A

Aneuploidy is a frequent event in human embryos, and its incidence is higher in oocytes and embryos from women of advanced maternal age. Aneuploidy may also be a contributing factor in infertile populations, such as couples with recurrent miscarriages, repetitive implantation failure, or male infertility. For these reasons, preimplantation genetic testing for aneuploidy (PGT-A) has been proposed to prevent miscarriages and increase live birth rates in infertile couples undergoing in vitro fertilisation. Next-generation sequencing is currently being applied for the detection of aneuploidies in human embryos, including whole chromosome aneuploidies, segmental aneuploidies, uniform, and mosaic aneuploidies. More recently, this technology has been incorporated for the analysis of the cell-free DNA secreted by the embryo to the culture media. Chromosome abnormalities mostly originate in female meiosis. Recombination between homologous chromosomes is a critical event that occurs in the foetal ovary. The importance of altered recombination pertains to paternally as well as maternally derived trisomies, but as most aneuploidy arises during oogenesis, the female is at greater risk. For males, sperm concentration is associated with a higher risk of aneuploid sperm and thus aneuploid embryos. Mitosis errors can occur at all stages of early embryo development that result in chromosomally distinct cell populations. The clinical impact of mosaicism depends on the mosaicism type, location, and number of aneuploid cells. Transfer of mosaic embryos has been proposed when no euploid embryos are available in the PGT-A cycle.

H A Morris, Lee; M McCue, P; Aurich, Christine

doi: 10.1530/rep-19-0478pmid: 32805710

Endometritis in the mare begins as a normal physiological inflammatory response to breeding that involves both a mechanical and immunological response pathway activated to rid the uterus of semen and bacteria. With successful resolution of this inflammation, the mare‘s uterus will provide a hospitable environment for the development of the semi-allogenic conceptus. If the mare fails to resolve this inflammatory response within 48 h of breeding, she will become susceptible to persistent breeding-induced endometritis (PBIE) which will have detrimental effects on her fertility. This condition can then predispose the mare to bacterial or fungal endometritis leading to further degeneration of the endometrium. Optimisation of the mare’s fertility requires a fine balance between allowing the natural immune response of the endometrium to its exposure to allogenic semen to run its course, and yet preventing its progression to PBIE or the involvement of infectious agents. This review discusses the challenges presented by PBIE, latent infections, biofilms, fungal infections and the need to utilise diagnostic methods available and implement targeted treatments to optimise fertility in the mare.

Tšuiko, Olga; Fernandez Gallardo, Elia; Voet, Thierry; Vermeesch, Joris Robert

doi: 10.1530/rep-20-0102pmid: 33065545

While chromosomal mosaicism in the embryo was observed already in the 1990s using both karyotyping and FISH technologies, the full extent of this phenomenon and the overall awareness of the consequences of chromosomal instability on embryo development has only come with the advent of sophisticated single-cell technologies. High-throughput techniques, such as DNA microarrays and massive parallel sequencing, have shifted single-cell genome research from evaluating a few loci at a time to the ability to perform comprehensive screening of all 24 chromosomes. The development of genome-wide single-cell haplotyping methods have also enabled for simultaneous detection of single-gene disorders and aneuploidy using a single universal protocol. Today, three decades later haplotyping-based embryo testing is performed worldwide to reliably detect virtually any Mendelian hereditary disease with a known cause, including autosomal-recessive, autosomal-dominant and X-linked disorders. At the same time, these single-cell assays have also provided unique insight into the complexity of embryo genome dynamics, by elucidating mechanistic origin, nature and developmental fate of embryonic aneuploidy. Understanding the impact of postzygotically acquired genomic aberrations on embryo development is essential to determine the still controversial diagnostic value of aneuploidy screening. For that reason, considerable efforts have been put into linking the genetic constitution of the embryo not only to its morphology and implantation potential, but more importantly to its transcriptome using single-cell RNA sequencing. Collectively, these breakthrough technologies have revolutionized single-cell research and clinical practice in assisted reproduction and led to unique discoveries in early embryogenesis.

Tšuiko, Olga; Fernandez Gallardo, Elia; Voet, Thierry; Vermeesch, Joris Robert

doi: 10.1530/rep-20-0102pmid: 33065545

While chromosomal mosaicism in the embryo was observed already in the 1990s using both karyotyping and FISH technologies, the full extent of this phenomenon and the overall awareness of the consequences of chromosomal instability on embryo development has only come with the advent of sophisticated single-cell technologies. High-throughput techniques, such as DNA microarrays and massive parallel sequencing, have shifted single-cell genome research from evaluating a few loci at a time to the ability to perform comprehensive screening of all 24 chromosomes. The development of genome-wide single-cell haplotyping methods have also enabled for simultaneous detection of single-gene disorders and aneuploidy using a single universal protocol. Today, three decades later haplotyping-based embryo testing is performed worldwide to reliably detect virtually any Mendelian hereditary disease with a known cause, including autosomal-recessive, autosomal-dominant and X-linked disorders. At the same time, these single-cell assays have also provided unique insight into the complexity of embryo genome dynamics, by elucidating mechanistic origin, nature and developmental fate of embryonic aneuploidy. Understanding the impact of postzygotically acquired genomic aberrations on embryo development is essential to determine the still controversial diagnostic value of aneuploidy screening. For that reason, considerable efforts have been put into linking the genetic constitution of the embryo not only to its morphology and implantation potential, but more importantly to its transcriptome using single-cell RNA sequencing. Collectively, these breakthrough technologies have revolutionized single-cell research and clinical practice in assisted reproduction and led to unique discoveries in early embryogenesis.

Sati, Leyla

doi: 10.1530/rep-20-0298pmid: 33065548

The circadian system regulates the daily temporal organization in behavior and physiology, including neuroendocrine rhythms and reproduction. Modern life, however, increasingly impacts this complex biological system. Due to limitations of working with human subjects exposed to shift work schedules, most chronoregulation research has used rodent models. Recent publications in these model systems have emphasized the negative effects of circadian rhythm disruption on both female and male reproductive systems and fertility. Additionally, there is growing concern about the long-term effects of circadian rhythm disruptions during pregnancy on human offspring and their descendants as circadian regulation during pregnancy can also alter epigenetic programing in offspring. However, to truly know if such concerns apply to humans will require retrospective and prospective human studies. Therefore, this review will highlight the latest available evidence regarding potential effects of chronodisruption on both female and male reproductive systems. Additionally, it presents a comprehensive summary of transgenerational and epigenetic effects on adult offspring that result from maternal chronodisruption.

Treff, Nathan R; Marin, Diego; Lello, Louis; Hsu, Stephen; Tellier, Laurent C A M

doi: 10.1530/rep-20-0071pmid: 32413844

Since its introduction to clinical practice, preimplantation genetic testing (PGT) has become a standard of care for couples at risk of having children with monogenic disease and for chromosomal aneuploidy to improve outcomes for patients with infertility. The primary objective of PGT is to reduce the risk of miscarriage and genetic disease and to improve the success of infertility treatment with the delivery of a healthy child. Until recently, the application of PGT to more common but complex polygenic disease was not possible, as the genetic contribution to polygenic disease has been difficult to determine, and the concept of embryo selection across multiple genetic loci has been difficult to comprehend. Several achievements, including the ability to obtain accurate, genome-wide genotypes of the human embryo and the development of population-level biobanks, have now made PGT for polygenic disease risk applicable in clinical practice. With the rapid advances in embryonic polygenic risk scoring, diverse considerations beyond technical capability have been introduced.

S Nagpal, Taniya; F Mottola, Michelle

doi: 10.1530/rep-20-0337pmid: 32805707

According to The Developmental Origins of Health and Disease theory, the intrauterine environment of the developing fetus may impact later life physiology, including susceptibility to chronic disease conditions. Maternal exposures during pregnancy can affect the intrauterine environment and result in fetal programming for chronic diseases through changes in the structure or function of specific organs. Negative maternal exposures, such as poor nutrition intake, have been shown to increase the risk for later life chronic diseases. On the contrary, healthful behaviors, such as physical activity, may have a positive and protective effect against chronic disease risk. This narrative review summarizes literature to discuss the potential preventative role prenatal physical activity may have on prevalent chronic diseases: obesity, type 2 diabetes, and cardiovascular disease. We describe the natural physiological response to pregnancy that may increase the risk for complications and consequently later life disease for both mother and baby. We then present evidence highlighting the role prenatal exercise may have in preventing pregnancy complications and downstream chronic disease development, as well as proposing potential mechanisms that may explain the protective maternal and fetal physiological response to exercise. As the prevalence of these non-communicable diseases increase globally, intervening during pregnancy with an effective exercise intervention may be the key to preventing chronic disease risk in more than one generation.

De Rycke, Martine; Berckmoes, Veerle; De Vos, Anick; Van De Voorde, Stefanie; Verdyck, Pieter; Verpoest, Willem; Keymolen, Kathelijn

doi: 10.1530/rep-20-0082pmid: 33112789

Thirty years of rapid technological advances in the field of genetic testing and assisted reproduction have reshaped the procedure of preimplantation genetic testing (PGT). The development of whole genome amplification and genome-wide testing tools together with the implementation of optimal hormonal stimulation protocols and more efficient cryopreservation methods have led to more accurate diagnoses and improved clinical outcomes. In addition, the shift towards embryo biopsy at day 5/6 has changed the timeline of a typical PGT clinical procedure. In this paper, we present an up-to-date overview of the different steps in PGT from patient referral to baby follow-up.