Abstract Postponement of fatherhood is growing worldwide due to socio-economic factors. The choice to conceive the first child above the age of 35 years is often associated with reduced fertility and poor pregnancy outcome. As widely known, several factors ( e.g. , lifestyle, environment, health problems) can affect spermatogenesis leading to poor reproductive outcome. Currently, the debate on the influence of aging on male gametes and safety/risk of conception at advanced age is still ongoing. Controversial results have been published so far on the changes in semen features of aging men and other mammalian species (mainly rodents). In this study, we aimed to assess how aging affects sperm quality in an inbreed mouse model, without underlying infertility, using a flow cytometry approach. Our data showed that aging is associated with increased sperm chromatin condensation, but not changes in the DNA integrity, metabolic activity or viability. These data suggest a mild effect of aging on sperm quality in a mouse model without underlying infertility.
Significance Lipid droplets (LDs) are stored in the embryo throughout the preimplantation development. Yet, the role of LDs in the embryo remains unknown. Embryonic diapause (ED) is a temporary arrest of an embryo when it waits for the uterine receptivity signal to implant. We provide evidence that LDs play a crucial role in maintaining ED. Diapausing embryos exhibit increased release of exosomes reflecting elevated embryonic signaling to the mother. During ED, the decrease in lipid is caused by a switch from carbohydrate metabolism to lipid catabolism. We have also shown that presence of LDs in the oocytes of various mammals positively corelates with their species-specific length of diapause. Our results reveal the functional role of LDs in embryonic development.
Conception of a child at advanced parental age (> 35 years) has been steadily increasing in recent decades, especially in developed countries. Socio-economic factors, effective contraceptives, and the availability of Assisted Reproduction Technologies (ART) have a direct impact on postponing the decision to have a baby. ART enables reproductive success for people diagnosed as infertile or with reduced possibilities of becoming pregnant due to concomitant pathologies. Epidemiological studies indicate that both advanced parental age and ART are associated with pathologies of pregnancy, such as gestational diabetes, risk of pre-eclampsia, miscarriage, placental abruption, preterm labor, stillbirth, neurodevelopmental disorders and chronic disease of the offspring. In our work, we will focus on the available information on metabolic changes that increase the risk of developing cardiovascular diseases in the offspring of parents at an advanced age and conceived through ART. Finally, we will address the sources of the observed disturbances at the gamete and embryo level, related to oxygen stress, epigenetic modifications and DNA damage, considering possible rescue actions.W Europie na opóźnione rodzicielstwo (w wieku >35 lat) decyduje się około 50% mężczyzn i 25% kobiet. W ostatnich dekadach, szczególnie w krajach rozwiniętych bezpośredni wpływ na odsuwanie decyzji o urodzeniu dziecka mają czynniki społeczno-ekonomiczne, skuteczne środki antykoncepcyjne oraz dostępność technologii wspomaganego rozrodu (ang. Assisted Reproduction Technologies, ART). Rozród wspomagany umożliwia sukces rozrodczy osobom diagnozowanym jako niepłodne lub o obniżonych możliwościach naturalnego zajścia w ciążę z uwagi na choroby, styl życia lub wiek. Badania epidemiologiczne wskazują, że zarówno zaawansowany wiek rodziców jak i ART są związane z podwyższonym ryzykiem powikłań ciąży, okresu okołoporodowego i poporodowego, takimi jak cukrzyca ciążowa, stan przedrzucawkowy, poronienia, oderwanie łożyska, poród przedwczesny, urodzenie martwego dziecka, zaburzenia neurorozwojowe i pogorszone wskaźniki ogólnego stanu zdrowia potomstwa [1-4]. Brakuje danych odnośnie stanu zdrowia dorosłego potomstwa poczętego w wyniku ART. W naszej pracy skupimy się na dostępnych informacjach dotyczących zmian metabolicznych zwiększających ryzyko rozwoju chorób sercowo--naczyniowych u potomstwa rodziców w zaawansowanym wieku rozrodczym oraz urodzonego przy pomocy ART**. Na koniec odniesiemy się do źródeł powstawania obserwowanych zaburzeń na poziomie gamety i zarodka, dotyczących modyfikacji epigenetycznych, stresu tlenowego oraz uszkodzeń DNA, rozpatrując możliwe działania naprawcze.
Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife
DNA damage is a hazard that affects all cells of the body. DNA-damage repair (DDR) mechanisms are in place to repair damage and restore cellular function, as are other damage-induced processes such as apoptosis, autophagy and senescence. The resilience of germ cells and embryos in response to DNA damage is less well studied compared with other cell types. Given that recent studies have described links between embryonic handling techniques and an increased likelihood of disease in post-natal life, an update is needed to summarize the sources of DNA damage in embryos and their capacity to repair it. In addition, numerous recent publications have detailed novel techniques for detecting and repairing DNA damage in embryos. This information is of interest to medical or scientific personnel who wish to obtain undamaged embryos for use in offspring generation by ART.This review aims to thoroughly discuss sources of DNA damage in male and female gametes and preimplantation embryos. Special consideration is given to current knowledge and limits in DNA damage detection and screening strategies. Finally, obstacles and future perspectives in clinical diagnosis and treatment (repair) of DNA damaged embryos are discussed.Using PubMed and Google Scholar until May 2021, a comprehensive search for peer-reviewed original English-language articles was carried out using keywords relevant to the topic with no limits placed on time. Keywords included 'DNA damage repair', 'gametes', 'sperm', 'oocyte', 'zygote', 'blastocyst' and 'embryo'. References from retrieved articles were also used to obtain additional articles. Literature on the sources and consequences of DNA damage on germ cells and embryos was also searched. Additional papers cited by primary references were included. Results from our own studies were included where relevant.DNA damage in gametes and embryos can differ greatly based on the source and severity. This damage affects the development of the embryo and can lead to long-term health effects on offspring. DDR mechanisms can repair damage to a certain extent, but the factors that play a role in this process are numerous and altogether not well characterized. In this review, we describe the multifactorial origin of DNA damage in male and female gametes and in the embryo, and suggest screening strategies for the selection of healthy gametes and embryos. Furthermore, possible therapeutic solutions to decrease the frequency of DNA damaged gametes and embryos and eventually to repair DNA and increase mitochondrial quality in embryos before their implantation is discussed.Understanding DNA damage in gametes and embryos is essential for the improvement of techniques that could enhance embryo implantation and pregnancy success. While our knowledge about DNA damage factors and regulatory mechanisms in cells has advanced greatly, the number of feasible practical techniques to avoid or repair damaged embryos remains scarce. Our intention is therefore to focus on strategies to obtain embryos with as little DNA damage as possible, which will impact reproductive biology research with particular significance for reproductive clinicians and embryologists.
High numbers of lipid droplets (LDs) in mammalian eggs are stored and maintained throughout embryo development without marked signs of their utilization. It was previously demonstrated in large domestic mammals that removing lipids from the zygote does not influence post-implantation development in terms of the rate of delivered offspring. Previously studied pig and cow eggs contain considerable amounts of LDs, while mice have a very low level of ooplasmic lipids, which allows to more precisely analyze any effect of lipid removal on developmental dynamics in vitro. We wanted to know if lipid fraction removal would influence the dynamics of preimplantation development of mouse embryos. To do this, mouse zygotes were mechanically delipidated and their progression to the blastocyst stage was evaluated in vitro. Part of blastocysts were transferred to pseudopregnant females for development to term, and then offspring health parameters were evaluated. Our experiments showed no effects of lipid removal on the rate and timing of mouse embryo development. Furthermore, there were no differences in post-natal characteristics of offspring developed from delipidated and non-delipidated embryos. In conclusion, normal developmental progression of dilapidated embryos indicates that LDs are largely unutilized during preimplantation stages. The apparent dispensability of the LDs fraction throughout preimplantation development prompts questions about their so far uncovered role in mammalian embryo. Based on our preliminary observation of the ultrastructure of diapaused blastocysts from mouse and sheep, we speculate that LDs are utilized by the embryo during delayed implantation, i.e., while waiting for the maternal receptivity signal before implantation.
Abstract Study question Does in vitro culture (IVC) induce changes in lipid profile of the embryo? Summary answer IVC induces changes in embryonic lipid homeostasis that subsequently affect placenta-brain axis (PBA) function and are then maintained in the brain of adult mice. What is known already During ART, embryos are exposed to oxidative stress (OS)-prone environment. Cellular lipids are particularly sensitive to OS. Lipids are a crucial component for proper brain development and any aberrancies in lipid profile of the embryo can affect neurodevelopment (ND) through the PBA, leading to functional and behavioural deficits during adulthood. In particular, deficiencies of ether-linked glicerophospolipids (e.g. plasmalogens), which are highly abundant in the brain, and polyunsaturated fatty acids (PUFAs), have been associated with psychiatric and ND disorders. Study design, size, duration C57BL6 mouse embryos were cultured in vitro for 72hs, and analysed or transferred to 25 recipient females for further development. From 6 pregnant mice, conceptuses (placentae and brain) were collected at near-term pregnancy (19dpc, n > 8/group). Remaining 8 pregnant mice were allowed to deliver and raise litters. Subsequently, brain was collected from male offspring at 4 month of age for lipid homeostasis evaluation. Control group consisted of embryos and offspring obtained from naturally mated C57BL6 mice. Participants/materials, setting, methods C57BL6 blastocysts (n > 15/group) were fixed and subjected to lipid analysis by Fourier transform infra-red (FTIR) and Coherent antistokes Raman spectroscopies (CARS). To reveal lipid changes indicative for ND disorders, selected PUFAs were analyzed by liquid chromatography-mass spectrometry (LC-MS) (n > 8/group) in placenta and brains from prenatal and adult mice. Additionally, placental expression of genes regulating biosynthesis of plasmalogens and proteome of adult males brain, was performed. Values were considered different when p < 0.05, Mean±SEM; Mann-Whitney test. Main results and the role of chance Our results show that IVC induced lipid composition changes in blastocyst, characterised by increased proportion of phospholipids, fatty amides and cholesterol (59±8.2 vs.44.7±8.8; 149±4.5vs. 104±12; 44±2.9vs. 27±4.6 sum of absorbance, p < 0.05); and lipid droplets (LDs) distribution changes, such as, increase size (2.3±0.11 vs 1.8±0.07 µm2, p = 0.0021), and number of large LDs (5.5±0.7 vs. 3.3±0.2, p = 0.006). LC-MS revealed increased levels of linolenic (LA), arachidonic (AA) and docosahexaenoic (DHA) acids in placenta (LA:15.49±1.7 vs. 6.92±2; AA:263.6±29.1 vs. 62.7±14.7 DHA:0±2.5 vs. 2.7±0.8 pmol/mg; p < 0.03) and foetal brain (LA:13.6±5.5 vs. 1.5±0.9; AA:240.5±100 vs. 39.3±9.6; 13.9±6.9 vs. 2.11±0.6 pmol/mg; p < 0.03) of IVC conceptuses, which may condition brain development and function. Conversely, levels of LA and AA were low in adult brain from IVC offspring (LA:4.4±1.5 vs 14.5±3.8; AA: 581±95 vs 1842±454 pmol/mg, p < 0.04). Additionally, the expression of genes regulating biosynthesis of plasmalogens was reduced in IVC placentae (Gnpat:0.2±0.04 vs 1.2±03; Tmem189:0.3±0.1 vs. 1.3±0.3 fold change; p ≤ 0.01). Proteome analysis demonstrated that pathways regulating lipid homeostasis, such as fatty acid oxidation and phospholipid binding and those involved in IL-17a signaling and neurogenesis were upregulated in brain of adult IVC offspring. Limitations, reasons for caution Our results may not entirely reflect what occurs in human embryo, as mouse oocytes have a higher lipid content than human oocyte. Differences in lipid content may cause an increased or decreased penetrance and exhibition of developmental changes of the embryos. Wider implications of the findings Being of non-genetic background, lipid changes induced by IVC may similarly threaten embryos regardless of species causing ND disorders. Our study sheds new light on non-genetic origins of ND disorders and will likely ignite further studies on embryonic lipid changes and their consequences, relevant for human pregnancy and neuropsychiatry. Trial registration number not applicable
