Incubating frozen-thawed buffalo sperm with olive fruit extracts counteracts thawing-induced oxidative stress and improves semen quality

Freezing-thawing procedures and semen manipulation for in vitro fertilization induce oxidative stress, which in turn leads to impaired sperm quality. The aim of this study was to evaluate whether incubation of frozen-thawed buffalo semen with olive fruit extracts (OFE), known to contain a high concentration of phenolic antioxidants, would improve semen quality by reducing oxidative stress. Frozen sperm (4 ejaculates/4 bulls/3 replicates) were thawed and diluted to 30 × 106/mL in IVF medium with 0, 72, 143, and 214 μL/mL of OFE, corresponding to 0 (D0-control), 50 (D50), 100 (D100), and 150 (D150) μM hydroxytyrosol. Sperm viability, acrosome integrity, membrane functionality, motility, and sperm kinetics were evaluated immediately after thawing (T0) and after 1 (T1) and 2 h (T2) of incubation at 38.7 °C. Based on the results, sperm biological antioxidant potential (BAP) and ROS levels (ROMs) were assessed in D0 and D100 groups at T1 and T2. To assess the effect of OFE on fertilizing ability, heterologous penetration rates were also evaluated, using bovine abattoir-derived oocytes. The treatment with OFE at all concentrations tested increased (P < 0.05) the percentage of acrosome intact spermatozoa compared to the D0-control at T1, but the effect was more evident (P < 0.01) with D100 (54.5 ± 3.0, 60.5 ± 1.5, 65.2 ± 3.3, and 62.5 ± 1.7, with D0, D50, D100, and D150 OFE, respectively). Total motility, progressive motility, rapid velocity, and progressive velocity decreased (P < 0.05) at T2 only in the D0-control group. The percentage of rapidly progressive sperm and the progressive motility tended to increase (P < 0.10) at T1 and T2, respectively, in D100 compared to D0 (24.7 ± 4.1 vs 16.4 ± 1.6 and 22.8 ± 2.7 vs 17.0 ± 1.2, respectively). The treatment with D100 OFE of frozen-thawed sperm increased (P < 0.05) some kinetic parameters (VAP and WOB). Spermatozoa incubated with D100 OFE exhibited higher (P < 0.01) total and normospermic oocyte penetration rates compared to D0 (86.5 ± 1.4 vs 78.5 ± 0.7, and 70.6 ± 1.5 vs 63.8 ± 1.1, respectively). Additionally, D100 OFE increased sperm BAP concentrations at both T1 and T2, while ROS levels were unaffected. These results suggest that incubating frozen-thawed buffalo semen with OFE is an effective strategy for preserving semen quality and in vitro fertilization ability by enhancing sperm antioxidant capacity.

Transwell Culture with Adipose Tissue-Derived Stem Cells and Fertilized Eggs Mimics the In Vivo Development of Fertilized Eggs to Blastocysts in the Fallopian Tube: An Animal Study

Many countries, including Japan, are experiencing declining birth rates. Assisted reproductive technologies have consistently demonstrated good results in resolving infertility. Although the development of fertilized eggs into blastocysts has been recognized as a crucial step in assisted reproductive technologies, the involved mechanisms are currently unclear. Here, we established a new culture system for the in vitro development of fertilized eggs into blastocysts. In the Transwell culture system, the rate of blastocysts hatching from fertilized eggs cultured with adipose-derived stem cells (ASCs) was significantly higher than that of blastocysts cultured only with fertilized eggs. Gene ontology analysis revealed that the developed blastocysts displayed essential gene expression patterns in mature blastocysts. Additionally, when cultured with 3rd-passage ASCs, the developed blastocysts expressed the core genes for blastocyst maturation and antioxidant properties compared to those cultured only with fertilized eggs or cultured with 20th-passage ASCs. These results suggest that the Transwell culture system may imitate the in vivo tubal culture state for fertilized eggs. Exosomes derived from stem cells with stemness potential play a powerful role in the development of blastocysts from fertilized eggs. Additionally, the exosomes expressed specific microRNAs; therefore, the Transwell culture system resulted in a higher rate of pregnancy. In future, the extraction of their own extracellular vesicles from the culture medium might contribute to the development of novel assisted reproductive technologies.

Sperm freezing damage: the role of regulated cell death

Substantial progress in research on sperm cryopreservation has occurred since the twentieth century, especially focusing on improving sperm freezing procedures and optimizing semen extenders. However, the cellular biological mechanisms of sperm freezing damage are still unclear, which greatly restricts the promotion and development of sperm cryopreservation. An essential component of sperm freezing damage is the occurrence of cell death. Considering the existence of multiple types of cell death pathways, this review discusses connections between characteristics of regulated cell death (e.g., apoptosis and ferroptosis), and accidental cell death (e.g., intracellular ice crystals) with sperm freezing damage and explores possible future research directions in this field.

Different doses of recombinant FSH and determining parameters of oxidative stress

Background

This study aimed to examine if there is a connection between recombinant FSH dose and OS parameters in serum and the impact on IVF outcome.

Methods

This study consisted of 101 participants that went through IVF procedures. Parameter that were tested are SOD, SH groups and MDA. Serum samples were drawn before stimulation and on the last day of ovarian stimulation.

Results

Two groups were formed according to the dose of gonadotropins (rFSH). In both groups there were no significant differences in live-birth rate and miscarriage. In both groups mean serum MDA and SH-groups were significantly higher after ovarian stimulation, but mean serum SOD was significantly lower when compared to values before stimulation. There were less patients without OS before stimulation.

Conclusions

Our results suggest that there is a difference in serum concentration in groups SOD, SH groups and MDA at the beginning and at the end ovarian stimulation. On the other hand, dose of rFSH is not related with change of parameters for oxidative stress, quality of oocytes, embryos, fertilization, pregnancies, and miscarriage rate. Patients without oxidative stress before the IVF procedure needed lower doses of gonadotropins during stimulation.

Bioluminescence measurement of superoxide anion in infertile men with oxidative stress

Infertility is such an important issue in society today. In some cases of male infertility, the main cause is oxidative stress and the presence of reactive oxygen species in the environment or in sperm cells. All current techniques that measure oxidative stress, including the nitroblue tetrazolium Test, DNA Fragmentation Index, Malondialdehyde, and Endz Test are qualitative and semi-quantitative. These methods do not have good sensitivity and specificity. Semen samples from 50 infertile patients and 10 normal individuals were collected. The samples were examined for laboratory routine tests according to the WHO 2010 protocol. Oxidative stress tests, including DFI, NBT, and MDA, were performed for these two groups. Bioluminescence inhibition assay was performed for detection of O2.- in semen samples by aequorin. The normal individuals showed significantly better semen parameters than the patient's group. Significantly lower O2.- levels were seen in the patient's group compared to normal individuals. The cut-off value of O2.- levels in normal individuals was determined to be 8 × 105 RLU/s with a sensitivity of 100% and a specificity of 100%. Infertile patients, despite having reduced quality of semen parameters, have high O2.- levels, and this causes the intensity of bioluminescence to be quenched in these people.

The role of seminal reactive oxygen species assessment in the setting of infertility and early pregnancy loss

The male contribution to a couple suffering with adverse early pregnancy outcomes is being increasingly investigated. Seminal oxidative stress is considered to cause sperm DNA damage, thus affecting the functional capacity of the sperm. Multiple lines of evidence support an association between elevated seminal reactive oxygen species (ROS) and infertility. In the setting of assisted reproduction various factors in the in vitro environment, differing from the in vivo environment, may exacerbate oxidative stress. Furthermore, seminal ROS levels have been found to be higher in the male partners of couple's affected by both spontaneous and recurrent pregnancy loss. There are several methods by which to assess ROS levels however they are costly, inconsistent and their incorporation into clinical practice is unclear. The value of ROS assessment lies in the ability to plan targeted therapies to improve pregnancy and live birth rates. As such, further robust study is required before firm conclusions can be made to inform clinical practice. We aim to review the available evidence regarding the role of seminal ROS in infertility and pregnancy loss.

Ameliorative effect of chitosan nanoparticles in capacitation media on post-thawing in vitro fertilizing ability of bovine spermatozoa

This study aimed to investigate the effect of supplementation of chitosan nanoparticles (CSNPs) on the capacitation of bovine spermatozoa during the in vitro fertilization process. Hyperactivated motility (HAM) and acrosome reaction (AR) of sperm cells as well as in vitro fertilization and cleavage rates are the main parameters used to estimate the effect of CSNPs on bovine spermatozoa's fertilizing ability. In this study, three different concentrations of CSNPs (10, 20 and 100 μg/mL) were prepared and characterized. Motile spermatozoa were separated from frozen-thawed semen by a swim-up technique and capacitated in Sperm-TALP medium supplemented with heparin only without CSNPs treatment (positive control), heparin + 10 μg/mL CSNPs, heparin + 20 μg/mL CSNPs, heparin + 100 μg/mL CSNPs and the last one served as a negative control tube which supplemented with 10 μg/mL CSNPs without adding heparin. Sperm cells were incubated for 90 min at 39°C in a 5% CO2 incubator and evaluated every 30 min at intervals. Cumulus oophorus complex (COCs) were matured in a 5% CO2 incubator at 39°C and inseminated in vitro with frozen-thawed bull sperm of the above concentrations. The inseminated oocytes were incubated at 39°C in a 5% CO2 incubator for 24 h and then examined for evidence of fertilization. The results of this investigation showed that HAM and AR were best affected by CSNPs at a concentration of 20 μg/mL during an incubation time of 60 min. As time went on, the overall proportion of spermatozoa with progressive motility (PM) decreased across all groups, and a substantially lower value was found at the dose mentioned above. Additionally, the impact of sperm treated with CSNPs on fertilization rate was assessed. The outcomes demonstrated that in comparison to the other concentrations (10 and 100 μg/mL), the positive control and the negative control, the proportion of fertilized oocytes was significantly higher in the CSNPs concentration (20 μg/mL). In conclusion, it could be inferred from this investigation that CSNPs support sperm functions during IVF and can be used for biomedical interventions in bovine spermatozoa. Additionally, a high IVF rate was achieved by using sperm treated with CSNPs as CSNPs enhance sperm capacitation and acrosome reaction.

Myo-inositol improves the viability of boar sperm during liquid storage

Introduction

Liquid preservation of boar semen is a highly preferred method for semen preservation in pig production. However, oxidative stress is the main challenge during the liquid preservation of boar semen in a time dependent manner. Therefore, supplementation of sperm with antioxidants during storage to protect them from oxidative stress has been the focus of recent research. Myo-inositol (Myo-Ins), the most active form of inositol, which belongs to the vitamin (Vit.) (B1 group has been shown to improve semen quality) (1). This study aimed to investigate whether Myo-Ins supplementation protects boar sperm in liquid preservation against oxidative stress and determine the appropriate concentration of Myo-Ins to be used in this regard.

Methods

Boar sperm was diluted with a semen extender with different concentrations of Myo-Ins (2, 4, 6, and 8 mg/mL) depending on the previous studies (1, 24). Sperm motility and viability, plasma membrane and acrosome integrity, mitochondrial membrane potential (MMP), semen time survival, and gene expression were measured and analyzed on days 0, 1, 3, 5, and 7 for the different samples.

Results

Different concentrations of Myo-Ins exerted different protective effects on the boar sperm quality. The addition of 2 mg/mL Myo-Ins resulted in higher sperm motility and viability, plasma membrane and acrosome integrity, MMP, and effective survival time. Investigation of mRNA expression patterns via qRT-PCR suggested that the 2 mg/mL Myo-Ins sample had increased expression of antioxidative genes.

Conclusion

The addition of Myo-Ins to semen extender improved the boar semen quality by decreasing the effects of oxidative stress during liquid preservation at 17°C. Additionally, 2 mg/mL is the optimum inclusion concentration of Myo-Ins for semen preservation.

Effect of Atomized Black Maca (Lepidium meyenii) Supplementation in the Cryopreservation of Alpaca (Vicugna pacos) Epididymal Spermatozoa

Artificial insemination is an important assisted reproductive technology that has been applied in several mammalian species. However, successful cryopreservation of semen of South American camelids has been limited, hindering the commercial application of artificial insemination in alpaca species. In this scenario, the addition of antioxidants to semen extenders provides a strategy to improve the freezability of mammalian sperm. Bioactive metabolites from natural extracts of black maca have shown valuable antioxidant properties. Thus, the objective of this study was to evaluate the effect of the addition of atomized black maca in the freezing medium of epididymal spermatozoa of alpacas. Fifteen pairs of epididymis were collected from a local slaughterhouse. Each sample was divided into six groups: (1) fresh, (2) yolk medium (YM), (3) 10 mg/mL maca, (4) 20 mg/mL maca, (5) 30 mg/mL maca, and (6) resveratrol (as an antioxidant control). Sperm cryopreservation was performed through the slow freezing method. Markers associated with functionality, such as motility, viability, and plasma membrane integrity, as well as markers associated with oxidative damage, such as DNA integrity, total ROS production, and mitochondrial function, were analyzed. The results show that the supplementation with black maca (20 mg/mL) improved the sperm motility, viability, plasma membrane integrity, and mitochondrial function evaluated according to an index of formazan deposits. Similarly, the ROS production decreased with maca at 20 mg/mL, although the DNA integrity did not show any differences among the groups. These results suggest that maca at 20 mg/mL has cytoprotective effects during freezing/thawing of epididymal sperm of alpaca species. Further research will be focused on assessing the effects of maca supplementation on semen extenders by using biomolecular markers (proAKAP4) associated with fertility.

Female Reproductive Aging and Oxidative Stress: Mesenchymal Stem Cell Conditioned Medium as a Promising Antioxidant

The recent tendency to delay pregnancy has increased the incidence of age-related infertility, as female reproductive competence decreases with aging. Along with aging, a lowered capacity of antioxidant defense causes a loss of normal function in the ovaries and uterus due to oxidative damage. Therefore, advancements have been made in assisted reproduction to resolve infertility caused by reproductive aging and oxidative stress, following an emphasis on their use. The application of mesenchymal stem cells (MSCs) with intensive antioxidative properties has been extensively validated as a regenerative therapy, and proceeding from original cell therapy, the therapeutic effects of stem cell conditioned medium (CM) containing paracrine factors secreted during cell culture have been reported to be as effective as that of direct treatment of source cells. In this review, we summarized the current understanding of female reproductive aging and oxidative stress and present MSC-CM, which could be developed as a promising antioxidant intervention for assisted reproductive technology.

Oxidative Stress in Assisted Reproductive Techniques, with a Focus on an Underestimated Risk Factor

Based on current findings, the presence of oxidative stress has a significant impact on the quality of gametes and embryos when performing assisted reproductive techniques (ART). Unfortunately, in vitro manipulation of these cells exposes them to a higher level of reactive oxygen species (ROS). The primary goal of this review is to provide a comprehensive overview of the development of oxidative stress in female and male reproductive systems, as well as in the case of the pre-implantation embryo and its environment. This review also focuses on the origins of ROS and the mechanisms of oxidative stress-induced damage during ART procedures. A well-known but underestimated hazard, light exposure-related photo-oxidation, is particularly concerning. The effect of oxidative stress on ART outcomes, as well as the various strategies for preventing it, are also discussed. We emphasize the role and significance of antioxidants and light protection including forms, functions, and mechanisms in the development of gametes and embryos in vivo and in vitro.

Vitamin and Carotenoid Intake and Outcomes of In Vitro Fertilization in Women Referring to an Italian Fertility Service: A Cross-Sectional Analysis of a Prospective Cohort Study

BACKGROUND

Nutrition may impact reproductive health and fertility potential. The role of dietary antioxidants in affecting conception and birth outcomes is a topic of emerging interest.

METHODS

This cross-sectional analysis from a prospective cohort study aims to explore the relationship between the intake of antioxidants, vitamins, and carotenoids and the outcomes of assisted reproduction techniques. Information on the socio-demographic characteristics, health histories, lifestyle habits, and diet information of subfertile couples referred to a fertility center was obtained.

RESULTS

A total of 494 women were enrolled. According to the four IVF outcomes considered, 95% of women achieved good quality oocytes, 87% achieved embryo transfer, 32.0% achieved clinical pregnancies, and 24.5% achieved pregnancy at term. Associations were found between age and the number of good quality oocytes (p = 0.02). A moderate level of physical activity in the prior 5 years was associated with a better rate of achieving clinical pregnancy (p = 0.03). Smoking habits, alcohol intake, and caffeine consumption did not show associations with any outcome. No associations were found, even after accounting for potential confounders, with the intake of vitamins C, D, E, and α-carotene, β-carotene, beta-cryptoxanthin, lutein, and folate.

CONCLUSION

Further research is needed to understand how antioxidant intake may have a role in modulating fertility.

OXIDATIVE STRESS AND REPRODUCTIVE FUNCTION: Reactive oxygen species in the mammalian pre-implantation embryo

In brief

Reactive oxygen species are generated throughout the pre-implantation period and are necessary for normal embryo formation. However, at pathological levels, they result in reduced embryo viability which can be mediated through factors delivered by sperm and eggs at conception or from the external environment.

Abstract

Reactive oxygen species (ROS) occur naturally in pre-implantation embryos as a by-product of ATP generation through oxidative phosphorylation and enzymes such as NADPH oxidase and xanthine oxidase. Biological concentrations of ROS are required for crucial embryonic events such as pronuclear formation, first cleavage and cell proliferation. However, high concentrations of ROS are detrimental to embryo development, resulting in embryo arrest, increased DNA damage and modification of gene expression leading to aberrant fetal growth and health. In vivo embryos are protected against oxidative stress by oxygen scavengers present in follicular and oviductal fluids, while in vitro, embryos rely on their own antioxidant defence mechanisms to protect against oxidative damage, including superoxide dismutase, catalase, glutathione and glutamylcysteine synthestase. Pre-implantation embryonic ROS originate from eggs, sperm and embryos themselves or from the external environment (i.e. in vitro culture system, obesity and ageing). This review examines the biological and pathological roles of ROS in the pre-implantation embryo, maternal and paternal origins of embryonic ROS, and from a clinical perspective, we comment on the growing interest in combating increased oxidative damage in the pre-implantation embryo through the addition of antioxidants.

Associations between mixtures of urinary phthalate metabolite concentrations and oxidative stress biomarkers among couples undergoing fertility treatment

Phthalate exposure has been associated with adverse reproductive outcomes and oxidative stress is a potential mechanism by which they act. However, few human studies have explored co-exposure confounding or joint effects. Furthermore, most studies examine associations between biomarkers of exposure and oxidative stress from the same urine sample. We investigated single-exposure, co-exposure-adjusted, and joint associations between phthalate metabolites and oxidative stress in the Environment and Reproductive Health (EARTH) study among couples undergoing fertility treatment. We examined cross-sectional associations in both women and men, and longitudinal associations in women. Urine was collected in the follicular phase (women only) and at the time of fertility procedure (women and men), and analyzed for 11 phthalate metabolites. Urine from the time of fertility procedure was analyzed for oxidative stress biomarkers, including free 8-iso-prostaglandin F2α (8-iso-PGF2α), its primary metabolite (2,3-dinor-5,6-dihydro-15-F2t-isoprostane [F2-IsoP-M]), and prostaglandin F2α (PGF2α). Linear mixed effects models were used to estimate single-exposure associations. Bayesian Kernel Machine Regression (BKMR) was used to adjust for co-exposures and to estimate joint effects. Among women, we observed positive associations between all phthalate metabolites and oxidative stress biomarkers in single-exposure models, but there was clear co-exposure confounding. For instance, in a single-exposure model, we estimated a 63% (95% confidence interval: 51, 77) increase in the 8-iso-PGF2α metabolite per interquartile range (IQR) difference in mono-n-butyl phthalate (MBP) versus a 34% (95% credible interval: 12, 60) increase in co-adjusted models. However, several phthalate metabolites remained associated with oxidative stress in co-exposure models, and the joint effects of all exposures were high (e.g., an 114% increase in the 8-iso-PGF2α metabolite per IQR difference in all exposures). Longitudinal results were also attenuated compared to cross-sectional results in women; however, the joint effect of all exposures and the 8-iso-PGF2α metabolite remained positive and statistically significant (11% increase per IQR difference in all exposures, 95% credible interval: 0.2, 23). In men, associations were generally less pronounced, although the joint effect of the mixture on 8-iso-PGF2α was above the null. Because oxidative stress is related to reproductive success among couples seeking fertility treatment, mitigating phthalate exposure should be considered as a potentially beneficial measure.

Mitochondrial metabolism determines the functional status of human sperm and correlates with semen parameters

The diagnosis of male infertility is based essentially on the patient’s medical history and a standard semen analysis. However, the latter rarely provides information on the causes of a possible infertility, emphasizing the need to extend the analysis of the sperm function. Mitochondrial function has been associated with sperm function and dysfunction, the latter primarily through the production of excessive amounts of reactive oxygen species (ROS). We hypothesized that analysis of sperm mitochondrial metabolism together with sperm ROS production could be an additional tool to improve routine semen analysis, after appropriate validations. To test our hypothesis, we performed several experiments using a non-routine method (high-resolution respirometry, HRR) to access mitochondrial function. First, we investigated whether mitochondrial function is related to human sperm motility and morphology. When mitochondrial metabolism was challenged, sperm motility decreased significantly. Additionally, morphological abnormalities in the sperm mid-piece and mitochondria were associated with global sperm defects evaluated by routine methods. Subsequently, sperm mitochondrial function was assessed by HRR. Respiratory control ratio (RCR) was determined and evaluated in the context of classical sperm analysis. In parallel, sperm hydrogen peroxide (H₂O₂) production and seminal plasma (SP) antioxidant capacity were measured. The percentage of sperm with progressive motility correlated positively with RCR, SP antioxidant capacity, and negatively with the concentration of extracellular H₂O₂ production ([H₂O₂]). The percentage of normal sperm morphology correlated positively with RCR and negatively with [H₂O₂]. Sperm morphology did not correlate with seminal plasma antioxidant capacity. Furthermore, Receiver Operating Characteristic curves were used for the first time to test the diagnostic ability of RCR, [H₂O₂], and SP antioxidant capacity as binary classifiers. An RCR cut off value of 3.2 was established with a sensitivity of 73% and a specificity of 61%, using reference values considered normal or abnormal in routine semen analysis. The cut off value for [H₂O₂] was 0.2 μM/10⁶ sperm (sensitivity = 65%, specificity = 60%). There were no reference values for SP antioxidant capacity that distinguished between abnormal and normal sperm samples. We conclude that sperm mitochondrial function indices in combination with [H₂O₂] may be useful tools to complement the routine semen analysis.

Mitochondria Transfer from Adipose Stem Cells Improves the Developmental Potential of Cryopreserved Oocytes

Although it is not a well-established technology, oocyte cryopreservation is becoming prevalent in assisted reproductive technologies in response to the growing demands of patients’ sociological and pathological conditions. Oocyte cryopreservation can adversely affect the developmental potential of oocytes by causing an increase in intracellular oxidative stresses and damage to the mitochondrial structure. In this study, we studied whether autologous adipose stem cell (ASC) mitochondria supplementation with vitrified and warmed oocytes could restore post-fertilization development that decreased due to mitochondrial damage following cryopreservation. ASC mitochondria showed similar morphology to oocytes’ mitochondria and had a higher ATP production capacity. The vitrified-warmed oocytes from juvenile mice were supplemented with ASC mitochondria at the same time as intracellular sperm injection (ICSI), after which we compared their developmental capacity and the mitochondria quality of 2-cell embryos. We found that, compared to their counterpart, mitochondria supplementation significantly improved development from 2-cell embryos to blastocysts (56.8% vs. 38.2%) and ATP production in 2-cell embryos (905.6 & 561.1 pmol), while reactive oxygen species levels were comparable. With these results, we propose that ASC mitochondria supplementation could restore the quality of cryopreserved oocytes and enhance the embryo developmental capacity, signifying another possible approach for mitochondrial transplantation therapy.

Increasing vitamin D levels to improve fertilization rates in cattle

Recently, interest in supplementing vitamin D (Vit D) to improve aspects of health, mainly in human fertility, has emerged. Still, supplementation of Vit D above the minimum required levels has yet to be explored in cattle despite evidence for Vit D receptors in reproductive tissues. The objective of this study was to establish if a dose-response relationship exists between Vit D exposure and success of in vitro production (IVP) of embryos and, if acute supplementation of Vit D improves pregnancy rates during timed artificial insemination (TAI) of dairy cows. Cumulus-oocyte complexes (COCs) were obtained from ovaries acquired from a local abattoir and cultured in five different IVP treatments from three separate collections (Control, 50, 100, 150, and 200 ng/mL of 1,25(OH)2D3; n = 20-30 COCs/group). In Experiment 2, dairy breed cows (n = 100) were synchronized for TAI with the PresynchOvsynch protocol. Cows received 150,000 IU of Vit D (n = 48) or castor oil as control (n = 53) along with gonadotropin-releasing hormone (GnRH) 24 h before TAI. Serum samples were collected before and 24 h after treatment. A small cohort of cows (n = 4) received the same treatments in two separate cycles and follicular fluid (FF) was collected after 24 h for calcidiol (25OHD) analyses. Increased concentrations of Vit D resulted in decreased rates of maturation of COC (150 and 200 ng/mL vs. control and 50 ng/mL; P = 0.01). Supplementation with 50 ng/mL resulted in greater numbers of early blastocyst and blastocyst stage embryos (P < 0.009). Pregnancy at first breeding did not differ (P = 0.13) between groups, but serum 25OHD increased in treated females after 24 h (P = 0.002). The FF 25OHD levels were reflective of serum levels, however, the observed increase in the treatment cycle (P = 0.04) was parallel to an overall increase in serum 25OHD during the entire second cycle, likely due to increased environmental sunlight exposure (March, control vs. May, treatment). A similar increase in the serum 25OHD in the lactating commercial herd maintained in covered housing was not observed, although experiments were conducted during a similar timeframe. This herd had levels of 25OHD near the low end of sufficiency according to National Research Council (NRC) guidelines. We conclude mild Vitamin D supplementation with concentrations at the higher end of NRC guidelines can improve maturation rates of recovered COCs. However, longer term supplementation may be needed to appreciate any benefits on fertility.

Ameliorative effect of bee products on in vitro maturation of sheep oocytes

The present study was undertaken to investigate the possible stimulating effects of Nigella sativa (N. sativa) honey, natural Saudi Sider honey, and honeybee pollen to the in vitro maturation (IVM) medium of sheep oocytes on their subsequent development. Hence, immature oocytes were exposed to various concentrations of natural Nigella sativa (N. sativa), and Saudi Sider honey (5, 10, and 20%), as well as honeybee pollen (1, 10, 50 μg/ml) during an in vitro maturation period (24 hours). After the exposure time, the maturation rate, glutathione (GSH) concentration, and candidate gene expression (GDF-9, MPF, CMOS, IGF-1, and BAX) were evaluated. Our results showed that the maturation rate was higher in the groups challenged with the lowest level of the bee products (5% and 1 μg/ml) when compared with that in the control group; where the mean number of oocytes in the metaphase II stage reached 0.360 for the honeybee pollen-treated group, 0.293 for the N. sativa-treated group, and 0.203 for the natural Saudi Sider honey-treated group. The glutathione level was significantly increased in the group exposed to N. sativa honey when compared with the other groups. Concerning the gene expression results, the Saudi Sider honey treatment showed the best results for all the genes except the CMOS gene, which was significantly higher than the GI and GII groups and lower than the GIV group and the BAX gene which did not show a significant difference when compared with the other groups. In conclusion, the addition of natural honey and honeybee pollen at a low concentration to an IVM medium improved the in vitro maturation rate, increased the glutathione level, and gene expression of the in vitro matured ovine oocytes.

L-Cysteine improves bovine oocyte developmental competence in vitro via activation of oocyte-derived growth factors BMP-15 and GDF-9

This study was designed to investigate the effect of different concentrations of L-cysteine supplementation into the maturation medium on the oocyte nuclear maturation, cumulus cell expansion, ultrastructure of the oocytes and the expression of oocyte-derived growth factors BMP-15, GDF-9 and CB-1 genes. Cumulus oocyte complexes (COCs) were collected from cow's ovaries obtained from abattoir and incubated at 38.5°C in maturation media supplemented with 0, 0.6, 0.8 or 1 mM L-cysteine in 5% CO₂ under humidified air for 24 hr. We found that a significantly higher percentage of oocytes progressed to metaphase II stage in the in vitro maturation (IVM) medium supplemented with L-cysteine, particularly 0.8 mM group, compared with untreated control oocytes. Additionally, L-cysteine treatment significantly increased the number of expanded COCs and the degree of expansion of individual COCs. Results of RT-qPCR showed significant increase in expression levels of BMP-15 and GDF-9 in L-cysteine-treated groups compared with control one. Electron microgram showed improvement of cytoplasmic maturation regarding ultrastructure of the oocytes and oocyte-cumulus cell gap junction communication in all L-cysteine-treated groups especially 0.8 mM L-cysteine-treated one. In conclusion, supplementation of IVM medium with a potential anti-oxidant, L-cysteine can effectively improve in vitro oocytes cytoplasmic and nuclear maturation via activation of oocyte maturation related BMP-15 and GDF-9 genes in bovine oocytes, benefiting the extended researches about the potential applications of L-cysteine in mammalian breeding technologies.

Effects of astaxanthin supplementation in fertilization medium and/or culture medium on the fertilization and development of mouse oocytes

Objective

We investigated the effect of supplementing fertilization medium and/or culture medium with astaxanthin (AST) on the two phases of in vitro fertilization: gamete fertilization and embryo development.

Methods

Mouse cumulus-oocyte complexes were divided into four groups with 5 µM AST added to the fertilization medium (group 3, n=300), culture medium (group 2, n=300), or both media (group 4, n=290). No AST was added to the control group (group 1, n=300).

Results

The fertilization rate was significantly higher (p<0.001) in the groups using AST supplemented fertilization medium (group 3, 79.0%; group 4, 81.4%) than those without AST (group 1, 56.3%; group 2, 52.3%). The blastocyst rate calculated from the two-cell stage was significantly lower (p<0.001) in the groups using AST-supplemented embryo culture medium (group 2, 58.0%; group 4, 62.3%) than in those without AST (group 1, 82.8%; group 3, 79.8%). The blastocyst rate calculated from the number of inseminated oocytes was highest in group 3 (189/300, 63.0%) and lowest in group 2 (91/300, 30.3%) with statistical significance compared to other groups (p<0.001). There were significantly higher numbers of cells in the inner cell mass and trophectoderm, as well as significantly higher total blastocyst cell counts, in group 3 than in the control group.

Conclusion

An increased blastocyst formation rate and high-quality blastocysts were found only in the fertilization medium that had been supplemented with AST. In contrast, AST supplementation of the embryo culture medium was found to impair embryo development.

Impact of Oxidative Stress on Embryogenesis and Fetal Development

Multiple cellular processes are regulated by oxygen radicals or reactive oxygen species (ROS) where they play crucial roles as primary or secondary messengers, particularly during cell proliferation, differentiation, and apoptosis. Embryogenesis and organogenesis encompass all these processes; therefore, their role during these crucial life events cannot be ignored, more so when there is an imbalance in redox homeostasis. Perturbed redox homeostasis is responsible for damaging the biomolecules such as lipids, proteins, and nucleic acids resulting in leaky membrane, altered protein, enzyme function, and DNA damage which have adverse impact on the embryo and fetal development. In this article, we attempt to summarize the available data in literature for an in-depth understanding of redox regulation during development that may help in optimizing the pregnancy outcome both under natural and assisted conditions.

DNA Repair in Haploid Context

DNA repair is a well-covered topic as alteration of genetic integrity underlies many pathological conditions and important transgenerational consequences. Surprisingly, the ploidy status is rarely considered although the presence of homologous chromosomes dramatically impacts the repair capacities of cells. This is especially important for the haploid gametes as they must transfer genetic information to the offspring. An understanding of the different mechanisms monitoring genetic integrity in this context is, therefore, essential as differences in repair pathways exist that differentiate the gamete’s role in transgenerational inheritance. Hence, the oocyte must have the most reliable repair capacity while sperm, produced in large numbers and from many differentiation steps, are expected to carry de novo variations. This review describes the main DNA repair pathways with a special emphasis on ploidy. Differences between Saccharomyces cerevisiae and Schizosaccharomyces pombe are especially useful to this aim as they can maintain a diploid and haploid life cycle respectively.

Redox Regulation and Oxidative Stress in Mammalian Oocytes and Embryos Developed In Vivo and In Vitro

Oocytes and preimplantation embryos require careful regulation of the redox environment for optimal development both in vivo and in vitro. Reactive oxygen species (ROS) are generated throughout development as a result of cellular metabolism and enzyme reactions. ROS production can result in (i) oxidative eustress, where ROS are helpful signalling molecules with beneficial physiological functions and where the redox state of the cell is maintained within homeostatic range by a closely coupled system of antioxidants and antioxidant enzymes, or (ii) oxidative distress, where excess ROS are deleterious and impair normal cellular function. in vitro culture of embryos exacerbates ROS production due to a range of issues including culture-medium composition and laboratory culture conditions. This increase in ROS can be detrimental not only to assisted reproductive success rates but can also result in epigenetic and genetic changes in the embryo, resulting in transgenerational effects. This review examines the effects of oxidative stress in the oocyte and preimplantation embryo in both the in vivo and in vitro environment, identifies mechanisms responsible for oxidative stress in the oocyte/embryo in culture and approaches to reduce these problems, and briefly examines the potential impacts on future generations.

Objective sleep duration and timing predicts completion of in vitro fertilization cycle

PURPOSE

To examine associations between objectively measured sleep duration and sleep timing with odds of completion of an in vitro fertilization (IVF) cycle.

METHODS

This prospective cohort study enrolled 48 women undergoing IVF at a large tertiary medical center between 2015 and 2017. Sleep was assessed by wrist-worn actigraphy, 1-2 weeks prior to initiation of the IVF cycle. Reproductive and IVF cycle data and demographic and health information were obtained from medical charts. Sleep duration, midpoint, and bedtime were examined in relation to IVF cycle completion using logistic regression models, adjusted for age and anti-Müllerian hormone levels. A sub-analysis excluded women who worked non-day shifts to control for circadian misalignment.

RESULTS

The median age of all participants was 33 years, with 29% of women >35 years. Ten women had an IVF cycle cancelation prior to embryo transfer. These women had shorter sleep duration, more nocturnal awakenings, lower sleep efficiency, and later sleep timing relative to those who completed their cycle. Longer sleep duration was associated with lower odds of uncompleted IVF cycle (OR = 0.88; 95%CI 0.78, 1.00, per 20-min increment of increased sleep duration). Women with later sleep midpoint and later bedtime had higher odds of uncompleted cycle relative to those with earlier midpoint and earlier bedtime; OR = 1.24; 95%CI 1.09, 1.40 and OR = 1.33; 95%CI 1.17, 1.53 respectively, for 20-min increments. These results were independent of age, anti-Müllerian hormone levels, or sleep duration, and remained significant after exclusion of shift-working women.

CONCLUSIONS

Shorter sleep duration and later sleep timing increase the odds of uncompleted cycles prior to embryo transfer.

Effects of hydroethanolic extracts of Terminalia chebula and Thymbra spicata on ram fresh semen under normal and oxidative stress conditions

The objective of this study was to evaluate protective effects of hydroethanolic extracts of Terminalia chebula and Thymbra spicata on viability, lipid peroxidation (LPO) and DNA integrity of ram fresh semen under normal and oxidative stress (OS) conditions. Antioxidant activities of different concentrations of Terminalia chebula and Thymbra spicata extracts were evaluated with DPPH assay. Semen samples were taken from three fertile adult rams. After diluting semen with Tris-base extender, different concentrations of Terminalia chebula and Thymbra spicata (30, 300, and 3000 μg/ml) extracts were used under normal and induced OS conditions. The group not receiving any supplements was considered as control group. A total of 50 μM hydrogen peroxide was used to induce OS. MTT solution was added to each of treatment groups which were kept in an incubator at 37°C for 2 h. After incubation, readings were obtained by ELISA reader. DNA integrity and LPO were determined with acridine orange (AO) staining and malondialdehyde (MDA) assay. Higher concentrations of Terminalia chebula and Thymbra spicata extracts preserved viability and DNA integrity while reducing MDA concentrations compared to other treatment groups. Also, under induced OS, higher concentrations of both extracts reduced detrimental effects of H₂ O₂ . In conclusion, it seems that addition of Terminalia chebula and Thymbra spicata extracts can reduce induced OS in spermatozoa.

Improved quality and fertilizability of cryopreserved buffalo spermatozoa with the supplementation of methionine sulfoxide reductase A

BACKGROUND

The excessive reactive oxygen species produced during semen-freezing and -thawing damage the macromolecules resulting in impairment of cellular functions. Proteins are the primary targets of oxidative damage, wherein methionine residues are more prone to oxidation and get converted into methionine sulfoxide, thus affecting the protein function. The methionine sulfoxide reductase A (MsrA) catalyzes the conversion of methionine sulfoxide to methionine and restores the functionality of defective proteins.

OBJECTIVES

To establish the expression of MsrA in male reproductive organs, including semen and its effect on quality of cryopreserved semen upon exogenous supplementation, taking buffalo semen as a model.

MATERIALS AND METHODS

The expression of MsrA was established by immunohistochemistry, PCR, and Western blots. Further, the effect of recombinant MsrA (rMsrA) supplementation on the quality of cryopreserved spermatozoa was assessed in three treatment groups containing 1.0, 1.5, and 2.0 µg of rMsrA/50 million spermatozoa in egg yolk glycerol extender along with a control group; wherein the post-thaw progressive motility, viability, membrane integrity, and zona binding ability of cryopreserved spermatozoa were studied.

RESULTS

The MsrA was expressed in buffalo testis, epididymis, accessory sex glands, and spermatozoa except in seminal plasma. In group 2, the supplementation has resulted in a significant (p < 0.05) improvement as compared to the control group in mean progressive motility (47.50 ± 2.50 vs. 36.25 ± 2.63), viability (56.47 ± 1.85 vs. 48.05 ± 2.42), HOST (50.76 ± 1.73 vs. 44.29 ± 1.29), and zona binding ability of spermatozoa (149.50 ± 8.39 vs. 29.50 ± 2.85).

DISCUSSION AND CONCLUSION

In the absence of native MsrA of seminal plasma, the supplementations of rMsrA may repair the oxidatively damaged seminal plasma proteins and exposed sperm plasma membrane proteins resulting in better quality with a fivefold increase in fertilizability of frozen-thawed spermatozoa. The findings can be extended to other species to improve the semen quality with the variation in the amounts of rMsrA supplementation.

Implications of cryopreservation on structural and functional attributes of bovine spermatozoa: An overview

Sperm cryopreservation is an important adjunct to assisted reproduction techniques (ART) for improving the reproductive efficiency of dairy cattle and buffaloes. Improved understanding of mechanisms and challenges of bovine semen cryopreservation is vital for artificial insemination on a commercial basis. Although cryopreservation of bovine spermatozoa is widely practiced and advanced beyond that of other species, there are still major gaps in the knowledge and technology. Upon cryopreservation, disruption of spermatozoal plasma membrane configuration due to alterations in metabolic pathways, enzymes and antioxidants activity add to lower efficiency with loss of sperm longevity and fertilising ability. Therefore, the effective amalgamation of cryo-variables like ambient temperature, cooling and thawing rates, nucleation temperature, type and concentration of the cryoprotectant, seminal plasma composition, free radicals and antioxidant status are required to optimise cryopreservation. Novel strategies like supplementation of cholesterol-loaded cyclodextrins (CLC), nanovesicles, osteopontin, antioxidants, etc., in an extender and recent techniques like nano-purification and modified packaging have to be optimised to ameliorate the cryodamage. This article is intended to describe the basic facts about the sperm cryopreservation process in bovine and the associated biochemical, biophysical, ultra-structural, molecular and functional alterations.

The role of alpha lipoic acid in female and male infertility: a systematic review

OBJECTIVE

Infertility is an increasingly frequent health condition, which may depend on female or male factors. Oxidative stress (OS), resulting from a disrupted balance between reactive oxygen species (ROS) and protective antioxidants, affects the reproductive lifespan of men and women. In this review, we examine if alpha lipoic acid (ALA), among the oral supplements currently in use, has an evidence-based beneficial role in the context of female and male infertility.

METHODS

We performed a search from English literature using PubMed database with the following keywords: 'female infertility', 'male infertility', 'semen', 'sperm', 'sub-fertile man', 'alpha-lipoic acid', ' alpha lipoic acid', 'lipoid acid', 'endometriosis', 'chronic pelvic pain', 'follicular fluid' and 'oocytes'. We included clinical trials, multicentric studies and reviews. The total number of references found after automatically and manually excluding duplicates was 180. After primary and secondary screening, 28 articles were selected.

RESULTS

The available literature demonstrates the positive effects of ALA in multiple processes from oocyte maturation (0.87 ± 0.9% of oocyte in MII vs 0.81 ± 3.9%; p < .05) to fertilization, embryo development (57.7% vs 75.7% grade 1 embryo; p < .05) and reproductive outcomes. Its regular administration both in sub-fertile women and men shows to reduce pelvic pain in endometriosis (p < .05), regularize menstrual flow and metabolic disorders (p < .01) and improve sperm quality (p < .001).

CONCLUSIONS

ALA represents a promising new molecule in the field of couple infertility. More clinical studies are needed in order to enhance its use in clinical practice.

Dietary Antioxidants in the Treatment of Male Infertility: Counteracting Oxidative Stress

Infertility affects about 15% of the population and male factors only are responsible for ~25-30% of cases of infertility. Currently, the etiology of suboptimal semen quality is poorly understood, and many environmental and genetic factors, including oxidative stress, have been implicated. Oxidative stress is an imbalance between the production of free radicals, or reactive oxygen species (ROS), and the capacity of the body to counteract their harmful effects through neutralization by antioxidants. The purpose of this review, by employing the joint expertise of international researchers specialized in nutrition and male fertility areas, is to update the knowledge about the reproductive consequences of excessive ROS concentrations and oxidative stress on the semen quality and Assisted Reproduction Techniques (ART) clinical outcomes, to discuss the role of antioxidants in fertility outcomes, and finally to discuss why foods and dietary patterns are more innocuous long term solution for ameliorating oxidative stress and therefore semen quality results and ART fertility outcomes. Since this is a narrative review and not a systematic/meta-analysis, the summarized information in the present study should be considered cautiously.

Cellular and molecular alterations of buffalo oocytes cultured under two different levels of oxygen tension during in vitro maturation

This study was conducted to monitor the cellular and molecular changes of buffalo cumulus-oocytes complexes (COCs) cultured under high or low oxygen levels. Morphologically good quality COCs (n = 1627) were screened using brilliant cresyl blue (BCB) staining and placed into three groups (BCB+, BCB- and control). All groups of COCs were cultured under low (5%) or high (20%) oxygen tensions. Intracellular and molecular changes including oocyte ultrastructure, lipid contents, mitochondrial activity and transcript abundance of genes regulating different pathways were analyzed in the matured oocyte groups. The results revealed that oxygen tension did not affect cumulus expansion rates, however the BCB+ group had a higher (P ≤ 0.05) expansion rate compared with the BCB- group. BCB- oocytes recorded the lowest meiotic progression rate (P ≤ 0.05) under high oxygen levels that was linked with an increased level of reactive oxygen species (ROS) compared with the BCB+ oocytes. Ultrastructure examination indicated that BCB+ oocytes had a higher rate of cortical granules migration compared with BCB- under low oxygen tension. In parallel, our results indicated the upregulation of NFE2L2 in groups of oocytes cultured under high oxygen tension that was coupled with reduced mitochondrial activity. In contrast, the expression levels of MAPK14 and CPT2 genes were increased (P ≤ 0.05) in groups of oocytes cultured under low compared with high oxygen tension that was subsequently associated with increased mitochondrial activity. In conclusion, data from the present investigation indicated that low oxygen tension is a favourable condition for maintaining the mitochondrial activity required for nuclear maturation of buffalo oocytes. However, low-quality oocytes (BCB-) responded negatively to high oxygen tension by reducing the expression of gene-regulating metabolic activity (CPT2). This action was an attempt by BCB- oocytes to reduce the increased levels of endogenously produced ROS that was coupled with decreased expression of the gene controlling meiotic progression (MAPK14) in addition to nuclear maturation rate.

Comparison of Anti-Oxidative Effect of Human Adipose- and Amniotic Membrane-Derived Mesenchymal Stem Cell Conditioned Medium on Mouse Preimplantation Embryo Development

Oxidative stress is a major cause of damage to the quantity and quality of embryos produced in vitro. Antioxidants are usually supplemented to protect embryos from the suboptimal in vitro culture (IVC) environment. Amniotic membrane-derived mesenchymal stem cells (AMSC) have emerged as a promising regenerative therapy, and their paracrine factors with anti-oxidative effects are present in AMSC conditioned medium (CM). We examined the anti-oxidative potential of human AMSC-CM treatment during IVC on mouse preimplantation embryo development and antioxidant gene expression in the forkhead box O (FoxO) pathway. AMSC-CM (10%) was optimal for overall preimplantation embryo developmental processes and upregulated the expression of FoxOs and their downstream antioxidants in blastocysts (BL). Subsequently, compared to adipose-derived mesenchymal stem cell (ASC)-CM, AMSC-CM enhanced antioxidant gene expression and intracellular GSH levels in the BL. Total antioxidant capacity and SOD activity were greater in AMSC-CM than in ASC-CM. Furthermore, SOD and catalase were more active in culture medium supplemented with AMSC-CM than in ASC-CM. Lastly, the anti-apoptotic effect of AMSC-CM was observed with the regulation of apoptosis-related genes and mitochondrial membrane potential in BL. In conclusion, the present study established AMSC-CM treatment at an optimal concentration as a novel antioxidant intervention for assisted reproduction.

Supplementing post-wash asthenozoospermic human spermatozoa with coenzyme Q10 for 1 hr in vitro improves sperm motility, but not oxidative stress

We investigated the effect of supplementing post-wash asthenozoospermic spermatozoa with coenzyme Q10 (CoQ10) in vitro, which may reduce oxidative stress and improve sperm motility. Semen samples were collected from 39 men with asthenozoospermia, and their spermatozoa were isolated by two-layer Percoll density-gradient centrifugation. Kinetic parameters of the isolated spermatozoa (baseline before intervention) were determined immediately by computer-aided semen analysis. Total anti-oxidant capacity and protein carbonyl levels, as markers of oxidative stress, were also measured in the baseline spermatozoa. The baseline spermatozoa suspension was divided equally into two portions, one for CoQ10 supplementation (50 µg/ml for 1 hr) and the other as an un-supplemented vehicle control. The total motility of the CoQ10-supplemented spermatozoa was significantly higher than in the control (p = .009) and progressive motility tended to be higher (p = .053). Immotile sperm concentration in the CoQ10-supplemented spermatozoa was significantly lower than in both the baseline (p = .026) and control (p = .009). Total anti-oxidant capacity and protein carbonyl levels between the baseline, CoQ10-supplemented and control spermatozoa were not significantly different. Our data suggest that CoQ10 treatment reactivated sperm motility. We propose short-term supplementation of post-wash asthenozoospermic spermatozoa with CoQ10 before intrauterine insemination.

Ameliorating Effects of Natural Antioxidant Compounds on Female Infertility: a Review

The prevalence of female infertility cases has been increasing at a frightening rate, affecting approximately 48 million women across the world. However, oxidative stress has been recognized as one of the main mediators of female infertility by causing various reproductive pathologies in females such as endometriosis, PCOS, preeclampsia, spontaneous abortion, and unexplained infertility. Nowadays, concerned women prefer dietary supplements with antioxidant properties over synthetic drugs as a natural way to lessen the oxidative stress and enhance their fertility. Therefore, the current review is an attempt to explore the efficacy of various natural antioxidant compounds including vitamins, carotenoids, and plant polyphenols and also of some medicinal plants in improving the fertility status of females. Our summarization of recent findings in the current article would pave the way toward the development of new possible antioxidant therapy to treat infertility in females. Natural antioxidant compounds found in fruits, vegetables, and other dietary sources, alone or in combination with other antioxidants, were found to be effective in ameliorating the oxidative stress-mediated infertility problems in both natural and assisted reproductive settings. Numerous medicinal plants showed promising results in averting the various reproductive disorders associated with female infertility, suggesting a plant-based herbal medicine to treat infertility. Although optimum levels of natural antioxidants have shown favorable results, however, their excessive intake may have adverse health impacts. Therefore, larger well-designed, dose-response studies in humans are further warranted to incorporate natural antioxidant compounds into the clinical management of female infertility.

Anti-Oxidative Effects of Human Adipose Stem Cell Conditioned Medium with Different Basal Medium during Mouse Embryo In Vitro Culture

Simple Summary

Assisted reproductive techniques, which are used to resolve various infertility problems, have advanced following the emphasis on their use. Embryos produced in vitro rather than in vivo are exposed to greater stress, with the quality of the embryos being affected by the in vitro culture conditions. To reduce oxidative stress and consequent apoptosis of embryos for successful implantation and pregnancy maintenance, the present study evaluated the anti-oxidative effect of human adipose stem cell conditioned medium (ASC-CM) with different basal medium as supplement in in vitro culture (IVC) medium for mouse preimplantation embryo. Treatment of 5% human ASC-CM based on Dulbecco′s modified Eagle′s medium (DMEM-CM) indicated an enhanced development of mouse in vitro fertilized embryo, decreased expression level of indicators for oxidative stress, and apoptosis in blastocysts. To our knowledge, this is the first study to demonstrate that DMEM-CM can be an optimal supplement during IVC to promote in vitro embryo development and the success rate of assisted reproduction with its anti-oxidative and anti-apoptotic effects.

Abstract

The quality of embryos produced by assisted reproductive techniques should be advanced by the improvement of in vitro culture conditions for successful implantation and pregnancy maintenance. We investigated the anti-oxidative effect of human adipose stem cell (ASC) conditioned medium with its optimal basal medium, Dulbecco′s modified Eagle′s medium (DMEM-CM), or keratinocyte serum-free medium (KSFM-CM) as supplements during in vitro culture (IVC) of in vitro fertilized mouse embryo. At first, preimplantation embryo development was evaluated in KSFM-CM and DMEM-CM supplemented cultures at various concentrations. The blastocyst (BL) and hatched BL formation rates were significantly increased in 5% DMEM-CM, while no difference was observed from KSFM-CM. Next, comparing the efficacy of KSFM-CM and DMEM-CM at the same concentration, DMEM-CM enhanced the developmental rate of 16 cells, morula, BL, and hatched BL. The expression level of reactive oxygen species decreased and that of glutathione increased in BL cultured with DMEM-CM, which confirms its anti-oxidative effect. Furthermore, apoptosis in BL cultured with DMEM-CM was reduced compared with that in KSFM-CM. This study demonstrated that the comparative effect of human ASC-CM made of two different basal media during mouse embryo IVC and anti-oxidative effect of 5% DMEM-CM was optimal to improve preimplantation embryo development.

Evaluation of seminal oxidation-reduction potential in male infertility

The role of oxidative stress in male infertility has been broadly recognised, and the search for a new marker to determine the redox environment in semen has gained considerable interest. Oxidation-reduction potential (ORP) or redox potential, is a measure of the electron transfer from antioxidants to oxidants and provides information on the redox balance. In this review, the benefits of ORP as a new oxidative stress marker, the protocol for its evaluation and the importance of its measurement in the context of male infertility are discussed. In association with the standard semen analysis, seminal ORP has been analysed to evaluate semen quality and male fertility status. However, further studies are required to establish its use in assisted reproductive techniques (ART) practice.

Cryopreservation induces higher oxidative stress levels in Bos indicus embryos compared with Bos taurus

Freezing and thawing of Bos indicus embryos affect their quality for embryo transfer. The objective of this study was to compare the levels of reactive oxygen species between Bos indicus and Bos taurus embryos produced in vivo, before and after conventional freezing, as well as to analyze damage caused by apoptosis and lipid peroxidation. Bos indicus has higher levels of reactive oxygen species than Bos taurus embryos, both fresh (14.32 ± 1.41 auf vs 8.07 ± 1.15 auf (arbitrary units of fluorescence), P < 0.05) and after freezing (20.91 ± 1.21 auf vs 14.39 ± 0.58 auf, P < 0.05). The number of apoptotic nuclei is also significantly higher in Bos indicus embryos than Bos taurus (8.28 ± 0.80 vs 1 ± 0.57, P < 0.05) but highlighting a notable increase after the freeze-thaw process in both subspecies (Bos indicus from 8.28 ± 0.80 to 10.71 ± 0.42, P < 0.05; Bos taurus from 1 ± 0.57 to 5.5 ± 1.15, P < 0.05). Finally, although lipid peroxidation is lower in Bos indicus embryos before freezing in comparison with Bos taurus (2.46 ± 0.14 vs 4.20 ± 0.51), the effect after the freeze-thaw process showed an increase of 4.34 in Bos indicus than Bos taurus embryos (51.45 ± 5.52 auf vs 11.85 ± 2.88 auf, P < 0.05). In conclusion, in comparison with Bos taurus, Bos indicus embryos undergo greater oxidative stress causing increases in the cryopreservation process, promoting major cell damage and lowering embryonic viability.

Epicatechin Provides Antioxidant Protection to Bovine Spermatozoa Subjected to Induced Oxidative Stress

Epicatechin (EPI) is a natural flavonoid with antibacterial, anti-inflammatory and anti-cancer properties. Furthermore, the molecule exhibits powerful reactive oxygen species (ROS) scavenging and metal-chelating properties. In this study, we assessed the efficiency of EPI to reverse ROS-mediated alterations to the motility, viability, DNA integrity and oxidative profile of bovine spermatozoa. For the first experiment, spermatozoa were washed out of fresh semen and exposed to 12.5 μmol/L EPI, 25 μmol/L EPI, 50 μmol/L EPI and 100 μmol/L EPI in the presence of ferrous ascorbate (FeAA) during a 6 h in vitro culture. For the second experiment, the ejaculates were split into aliquots and cryopreserved with a commercial semen extender supplemented with 12.5 μmol/L EPI, 25 μmol/L EPI, 50 μmol/L EPI, 100 μmol/L EPI or containing no supplement. Sperm motility was assessed using the computer-aided sperm analysis and the cell viability was studied with the metabolic activity test. ROS production was quantified using luminometry, and DNA fragmentation was evaluated using the chromatin dispersion test. Cell lysates were prepared at the end of the culture in order to assess the concentration of protein carbonyls and malondialdehyde. Exposure to FeAA led to a significantly reduced sperm motility (p < 0.001), mitochondrial activity (p < 0.001), but increased the generation of ROS (p < 0.001), as well as oxidative damage to proteins (p < 0.001), DNA (p < 0.001) and lipids (p < 0.001). EPI supplementation, particularly at a concentration range of 50–100 μmol/L, resulted in higher preservation of the spermatozoa vitality (p < 0.001). Furthermore, 50–100 μmol/L EPI were significantly effective in the prevention of oxidative damage to sperm proteins (p < 0.001), lipids (p < 0.001) and DNA (p < 0.01 in relation to 50 μmol/L EPI; p < 0.001 with respect to 100 μmol/L EPI). In the case of the cryopreserved spermatozoa, the administration of 50–100 μmol/L EPI resulted in higher sperm motility (p < 0.001) and mitochondrial activity (p < 0.001). ROS production, the number of protein carbonyls, lipid peroxidation as well as oxidative DNA damage were found to be significantly decreased particularly in samples cryopreserved in the presence of 100 μmol/L EPI (p < 0.001). Our results suggest that EPI could behave as an effective antioxidant which may prevent oxidative insults to spermatozoa, and thus, preserve their vitality and functionality. Nevertheless, its potential to achieve higher fertilization rates in reproductive technologies needs to be validated.

Strategies to Minimize Various Stress-Related Freeze-Thaw Damages During Conventional Cryopreservation of Mammalian Spermatozoa

The aim of the article is to report a review on different sperm cryopreservation techniques, various stress-related freeze-thaw damages altering sperm structure and function during conventional cryopreservation, and strategies to minimize these stresses. Sperm cryopreservation has allowed indefinite storage and successful transportation of valuable germplasm from proven sites at distant locations, for genetic upgradation through implementation of reproductive techniques, such as artificial insemination. Different techniques for sperm cryopreservation have been proposed such as conventional freezing techniques, directional freezing, and sperm vitrification. Drawbacks related to conventional freezing methods, such as heterogeneous ice nucleation and repeated freeze-thaw cycles at the ice front that disrupts and kill sperm cells, led to the emergence of the directional freezing technique. Sperm vitrification is advantageous as there is no ice crystal-induced physical damages to sperm. However, sperm vitrification has less applicability as encouraging results are only reported in human, dog, and cat. In spite of several drawbacks, conventional freezing techniques are still most widely used for sperm cryopreservation. Spermatozoa experience stresses in the form of cold shock, osmotic stress, and mainly oxidative stress during conventional cryopreservation ultimately reduces the sperm viability and fertility. Several attempts have been made in the past to minimize all these stresses individually or in combination. Membrane fluidity was increased to prevent the cold shock and cryocapacitation-like changes by the addition of cholesterol to the membrane. Antifreeze proteins were added in semen extender to minimize freeze-thaw damages due to heterogeneous ice nucleation and ice recrystallization. Oxidative stress was reduced either by neutralizing reactive oxygen species (ROS) through enzymatic, nonenzymatic, plant-based antioxidants or reductants; or by minimizing the level of sources like the semen radiation exposure, leucocytes, and dead and defective spermatozoa, which lead to ROS production during the semen cryopreservation process. A novel approach of minimizing oxidative stress was to reduce the oxygen tension in sperm microenvironment that is, extender by partial deoxygenation process, as a number of literatures pointed out direct link of O₂ with ROS production. When compared with other strategies, partial deoxygenation of semen extender with N₂ gassing is found as a cost-effective, comparatively easy and a potential approach to large-scale frozen semen production.

Intake of Antioxidants in Relation to Infertility Treatment Outcomes with Assisted Reproductive Technologies

BACKGROUND

Randomized trials of supplementation with antioxidant mixtures during infertility treatment show no benefit on pregnancy or live birth rate. However, the roles of individual antioxidants are poorly understood. We examined the association of baseline intake of vitamins A, C, E, and carotenoids with outcomes of assisted reproductive technologies (ARTs).

METHODS

We followed 349 women undergoing a total of 588 ART cycles for infertility treatment at the Massachusetts General Hospital. We assessed antioxidant intakes from food and supplements before treatment using a validated food frequency questionnaire. We used generalized linear mixed models to account for multiple ART cycles per woman while adjusting for confounding.

RESULTS

Mean (SD) age and body mass index were 35.1 years (4.0 years) and 24.1 kg/m (4.3 kg/m), respectively. Total intake of vitamins A, C, and E was not associated with the probability of live birth. Women in the highest intake category of β-carotene from foods had a lower probability of live birth than women in the lowest intake quartile (50% vs. 22%; P trend = 0.03); for lutein and zeaxanthin, the probability for the highest intake group was 44% vs. 28% for the lowest. Intake of β-carotene from supplements and intakes of retinol and all other carotenoids were unrelated to live birth rates.

CONCLUSIONS

We found unexpected inverse associations of β-carotene intake from foods and of lutein and zeaxanthin intake with live birth rates. Within the observed intake ranges, total consumption of vitamins A, C, and E before starting infertility treatment with ART was not associated with live birth rates.

DNA Damage and Repair in Human Reproductive Cells

The fundamental underlying paradigm of sexual reproduction is the production of male and female gametes of sufficient genetic difference and quality that, following syngamy, they result in embryos with genomic potential to allow for future adaptive change and the ability to respond to selective pressure. The fusion of dissimilar gametes resulting in the formation of a normal and viable embryo is known as anisogamy, and is concomitant with precise structural, physiological, and molecular control of gamete function for species survival. However, along the reproductive life cycle of all organisms, both male and female gametes can be exposed to an array of “stressors” that may adversely affect the composition and biological integrity of their proteins, lipids and nucleic acids, that may consequently compromise their capacity to produce normal embryos. The aim of this review is to highlight gamete genome organization, differences in the chronology of gamete production between the male and female, the inherent DNA protective mechanisms in these reproductive cells, the aetiology of DNA damage in germ cells, and the remarkable DNA repair mechanisms, pre- and post-syngamy, that function to maintain genome integrity.

Relationship between nuclear DNA fragmentation, mitochondrial DNA damage and standard sperm parameters in spermatozoa of fertile and sub-fertile men before and after freeze-thawing procedure

The aim of this study was to assess the stability of nuclear and mitochondrial DNA (n-DNA and mt-DNA) of spermatozoa under freeze-thawing and to find out the correlation between them and their association with standard sperm parameters. Forty-three semen samples were collected from fertile (G.1; n = 29) and sub-fertile (G.2; n = 14). N-DNA fragmentation was determined by TUNEL assay and mt-DNA using caspase 3 staining. Each semen sample was frozen at -196°C by the programmed freezer. Freeze-thawing decrease vitality, total motility and membrane integrity from (43.02 ± 22.74%; 31.63 ± 18.15%; 51.5 ± 24.82%) to (22.71 ± 17.3%; 9.21 ± 6.61%; 34.64 ± 19.92% respectively [p < .001]). G.1 native spermatozoa stained positive with TUNEL and caspase 3 were (14.85 ± 17.6% and 5.8 ± 11.59%) and increased after freeze-thawing to 27.54 ± 19.74% (p = .004) and 7.3 ± 6.13% (p = .01) respectively. In G.2, TUNEL and caspase 3 were (19.84 ± 17.52% and 7.53 ± 8.56%) and increased to (29.48 ± 16.97% [p = .03] and 10.21 ± 11.73%). In conclusion, freeze-thawing process affects not only semen parameters but also n-DNA and mt-DNA. Therefore, n-DNA and mt-DNA could be used as sensitive parameters for assessment of the cryodamage of human spermatozoa.

A Biochemical Approach to Detect Oxidative Stress in Infertile Women Undergoing Assisted Reproductive Technology Procedures

Oxidative stress plays a major role in critical biological processes in human reproduction. However, a reliable and biologically accurate indicator of this condition does not yet exist. On these bases, the aim of this study was to assess and compare the blood and follicular fluid (FF) redox status of 45 infertile subjects (and 45 age-matched controls) undergoing in vitro fertilization (IVF), and explore possible relationships between the assessed redox parameters and IVF outcomes. Reactive Oxygen Species (ROS) production, assessed by flow cytometry analysis in blood leukocytes and granulosa cells, significantly increased (p < 0.05) in infertile patients. Also, oxidative stress markers—ThioBarbituric Acid-Reactive Substances (TBARS) as an index of lipid peroxidation, and Oxygen Radical Absorbance Capacity (ORAC) to account for total antioxidant capacity, both assayed by fluorometric procedures—in blood and FF were significantly (p < 0.001) modified in infertile patients compared to the control group. Moreover, a significant correlation between blood redox markers and FF redox markers was evident. An ORAC/TBARS ratio, defined as the redox index (RI), was obtained in the plasma and FF of the patients and controls. In the patients, the plasma RI was about 3.4-fold (p < 0.0001) lower than the control, and the FF RI was about six-fold (p < 0.0001) lower than the control. Interestingly, both the plasma RI and FF RI results were significantly correlated (p < 0.05) to the considered outcome parameters (metaphase II, fertilization rate, and ongoing pregnancies). Given the reported findings, a strict monitoring of redox parameters in assisted reproductive techniques and infertility management is recommended.

Oxidation-reduction potential as a new marker for oxidative stress: Correlation to male infertility

Male infertility affects men worldwide. Oxidative stress (OS), characterized by an overabundance of reactive oxygen species (ROS) or a deficiency of antioxidants, is one of the major causes of male infertility. OS causes damage at the molecular level, which impairs lipids, proteins, and DNA. The cyclic cascade of redox reactions weakens sperm function which leads to poor semen parameters and eventual sterility. There is a need for advanced diagnostic tests that can quickly and accurately detect OS. Most commonly used assays can only measure single constituents of OS. However, the MiOXSYS System introduces a new strategy to detect OS by measuring the oxidation-reduction potential (ORP)--a direct evaluation of the redox balance between ROS and antioxidants. The MiOXSYS System has shown promise as a diagnostic tool in the evaluation of male infertility. This review explores the concept of ORP, details the principle of the MiOXSYS System, and summarizes the findings in clinical studies that support ORP measurement in semen.

Role of Antioxidants in Assisted Reproductive Techniques

Oxidative stress (OS) has been recognized as a significant cause of suboptimal assisted reproductive outcome. Many of the sperm preparation and manipulation procedures that are necessary in the in vitro environment can result in excessive production of reactive oxygen species (ROS) thereby exposing the gametes and growing embryos to significant oxidative damage. Antioxidants have long been utilized in the management of male subfertility as they can counterbalance the elevated levels of ROS inducing a high state of OS. Few studies have looked into the clinical effectiveness of antioxidants in patients undergoing assisted reproduction. While an overall favorable outcome has been perceived, the specific clinical indication and optimal antioxidant regimen remain unknown. The goal of our review is to explore the sources of ROS in the in vitro environment and provide a clinical scenario-based approach to identify the circumstances where antioxidant supplementation is most beneficial to enhance the outcome of assisted reproduction.

The Consequences of Maternal-Embryonic Cross Talk During the Periconception Period on Subsequent Embryonic Development

The periconception period comprises the final maturation of sperm and the processes of fertilization and early embryonic development, which take place in the oviduct. The final goal of these important events is to lead to establishment of pregnancy leading to the birth of healthy offspring. Studies in rodents and domestic animals have demonstrated that environmental conditions experienced during early development affect critical aspects of future growth, metabolism, gene expression, and physiology. Similarly, in vitro culture of embryos can be associated with changes in fetal growth, gene expression and regulation, and postnatal behavior.In the oviduct, the cross talk between the mother and gametes/embryo begins after ovulation, between the oocyte and the female reproductive tract, and continues with the sperm and the early embryo after successful fertilization. These signals are mainly the result of direct interaction of gametes and embryos with oviductal and endometrial cells, influencing the microenvironment at the specific location. Identifying and understanding the mechanisms involved in this cross talk during the critical period of early reproductive events leading to pregnancy establishment could potentially lead to improvements in current in vitro embryo production systems in domestic mammals and humans. In this review, we discuss current knowledge of the short- and long-term consequences of in vitro embryo production on embryo development.