The influence of the redox state of follicular fluid albumin on the viability of aspirated human oocytes

Prolonged follicular dominance is associated with dysregulated proteomic profile of the follicular fluid in Bos indicus cows

Prolonged follicular dominance is one of the conditions associated with disconcerted follicular dynamics that result in substantial economic losses to the farmers through low reproductive efficiency in cattle. Hormonal aberrations associated with prolonged follicular dominance may affect the follicular microenvironment and composition of follicular fluid. The current study focused on proteome changes of follicular fluid in prolonged follicular dominance compared to physiological follicular dominance. Prolonged dominance was induced in Deoni cows (n = 6) by using CIDR (previously used for 7 days) from day 4-8 of estrus, with PGF2 injection on day 6 and day 7 at 12 h intervals. Follicular fluid was collected by ultrasound guided transvaginal follicular aspiration method. Global proteomic analysis of follicular fluid revealed 217 proteins in the Deoni cow, with the majority of proteins involved in 21 pathways, 42 molecular functions, and 106 biological processes. Complement and coagulation cascades (22.8%) and cholesterol metabolism (4.68%) were the major pathways in which identified proteins were involved. Comparison of physiological and prolonged dominant follicular fluid revealed differential expression of 26 proteins, of which 15 were upregulated and 11 were downregulated. Proteins involved in complement and coagulation cascades, and vitamin digestion and absorption were found to be dysregulated in PFD. The present study suggests that the expression of proteins involved in inflammation, oocyte metabolism, and ovulation cascade were found to be dysregulated in the follicular fluid of prolonged follicular dominance consequently resulting in delayed ovulation or anovulation.

Follicular Fluid Components in Reduced Ovarian Reserve, Endometriosis, and Idiopathic Infertility

Follicular fluid (FF) molecules, and their increase or decrease, can contribute to appropriate follicular growth and oocyte maturation, thus being related to female infertility conditions. In this paper, we studied the changes and the relationships of some biochemical components, hormones, antioxidant enzymes, F₂-Isoprostanes (F₂-IsoPs), and resolvin (Rv) D1 in the FF of infertile women with different reproductive conditions such as endometriosis, reduced ovarian reserve, and idiopathic infertility during assisted reproductive techniques (ART). In the whole population, positive correlations between albumin (ALB)/iron (Fe), ALB/beta-2-microglobulin (B2MG), and F₂-IsoPs/RvD1 were detected in the FF. In FF from aged women, increased levels of follicle stimulating hormone (FSH) and reduced anti-Müllerian hormone (AMH) levels were associated with a worse oocyte quality. The negative ART outcome was influenced by patient age and AMH, B2MG, and FSH levels. Moreover, the reduced ovarian reserve condition was characterised by a significant decrease in oocyte number and quality, AMH amount, and lactate dehydrogenase (LDH) activity, as well as by an increase in age and FSH levels. In the presence of endometriosis, high levels of MDA and RvD1 were detected in FF, with a decrease in luteinising hormone (LH). Finally, among the molecules examined, none characterised the condition of idiopathic infertility. These data could support the identification of new FF markers in different reproductive disorders, suggesting the need for personalised therapeutic approaches and optimised ART outcomes. In particular, the evaluation of resolvins and lipid mediators in FF could be a promising field of investigation with which to understand the entity of oxidative stress and inflammation in some female infertility conditions.

The Human Ovary and Future of Fertility Assessment in the Post-Genome Era

Proteomics has opened up new avenues in the field of gynecology in the post-genome era, making it possible to meet patient needs more effectively and improve their care. This mini-review aims to reveal the scope of proteomic applications through an overview of the technique and its applications in assisted procreation. Some of the latest technologies in this field are described in order to better understand the perspectives of its clinical applications. Proteomics seems destined for a promising future in gynecology, more particularly in relation to the ovary. Nevertheless, we know that reproductive biology proteomics is still in its infancy and major technical and ethical challenges must first be overcome.

A Novel Quantitative Method for the Detection of Lipofuscin, the Main By-Product of Cellular Senescence, in Fluids

Lipofuscin accumulation is a hallmark of senescence. This nondegradable material aggregates in the cytoplasm of stressed or damaged cells due to metabolic imbalance associated with aging and age-related diseases. Indications of a soluble state of lipofuscin have also been provided, rendering the perspective of monitoring such processes via lipofuscin quantification in liquids intriguing. Therefore, the development of an accurate and reliable method is of paramount importance. Currently available assays are characterized by inherent pitfalls which demote their credibility. We herein describe a simple, highly specific and sensitive protocol for measuring lipofuscin levels in any type of liquid. The current method represents an evolution of a previously described assay, developed for in vitro and in vivo senescent cell recognition that exploits a newly synthesized Sudan Black-B analog (GL13). Analysis of human clinical samples with the modified protocol provided strong evidence of its usefulness for the exposure and surveillance of age-related conditions.

Serum albumin concentration of donor cows as an indicator of developmental competence of oocytes

Adequate nutrition is required for maintenance of normal reproduction in cattle. Albumin, the best marker and fundamental part of nutrition, most abundant plasma protein and major component of fetal bovine serum, is the best predictor of malnourishment in South African cattle. The aim of this study was to determine if serum albumin concentrations of donor cows predict the developmental competence of oocytes, and if additional protein supplementation of the in vitro culture media improves embryo outcomes in oocytes from cows with inadequate serum albumin concentrations. Oocytes (n = 1024) were recovered from donors with inadequate (≤35.9 g/L), or adequate serum albumin concentrations (≥36.0 g/L). Four hundred and sixty oocytes originated from cows with inadequate serum albumin and 564 from cows with adequate serum albumin. Oocytes of these cohorts were randomly allocated to a control and supplemented fetal bovine serum in vitro embryo culture protocol. Multiple linear, logistic and Poisson regression analyses were performed to estimate the effects of different covariates on linear, binary and count data respectively. Mixed effects Poisson regression was performed for the number of oocytes that developed into blastocysts by the seventh day of culture. Adequate serum albumin concentration of donor cows independently resulted in 46% increased blastocyst formation in the control protocol (P = 0.02). Although fetal bovine serum supplementation of the culture protocol did not affect blastocyst formation in oocytes originating from cows with inadequate serum albumin, it independently reduced blastocyst formation by 30% in oocytes originating from cows with adequate serum albumin (P = 0.02). Other independent predictors of blastocyst outcome included higher serum urea nitrogen, lower beta (β)-hydroxybutyric acid concentrations and lower fat classification of donor cows. It is concluded that adequate serum albumin of donor cows is a significant predictor of developmental competence of oocytes, and that in vitro supplementation of fetal bovine serum does not improve developmental competence of oocytes and can lead to negative blastocyst outcomes. Further research is required to determine optimal protein supplementation for oocytes originating from inadequately nourished cows.

Follicular Fluid redox involvement for ovarian follicle growth

As the human ovarian follicle enlarges in the course of a regular cycle or following controlled ovarian stimulation, the changes in its structure reveal the oocyte environment composed of cumulus oophorus cells and the follicular fluid (FF).

In contrast to the dynamic nature of cells, the fluid compartment appears as a reservoir rich in biomolecules. In some aspects, it is similar to the plasma, but it also exhibits differences that likely relate to its specific localization around the oocyte. The chemical composition indicates that the follicular fluid is able to detect and buffer excessive amounts of reactive oxygen species, employing a variety of antioxidants, some of them components of the intracellular milieu.

An important part is played by albumin through specific cysteine residues. But the fluid contains other molecules whose cysteine residues may be involved in sensing and buffering the local oxidative conditions. How these molecules are recruited and regulated to intervene such process is unknown but it is a critical issue in reproduction.

In fact, important proteins in the FF, that regulate follicle growth and oocyte quality, exhibit cysteine residues at specific points, whose untoward oxidation would result in functional loss. Therefore, preservation of controlled oxidative conditions in the FF is a requirement for the fine-tuned oocyte maturation process. In contrast, its disturbance enhances the susceptibility to the establishment of reproductive disorders that would require the intervention of reproductive medicine technology.

Follicular fluid biomarkers for human in vitro fertilization outcome: Proof of principle

Background

Human follicular fluid (FF) is a unique biological fluid in which the oocyte develops in vivo, and presents an optimal source for non-invasive biochemical predictors. Oocyte quality directly influences the embryo development and hence, may be used as a predictor of embryo quality. Peptide profiling of FF and its potential use as a biomarker for oocyte quality has never been reported.

Methods

This study screened FF for peptide biomarkers that predict the outcome of in vitro fertilization (IVF). Potential biomarkers were discovered by investigating 2 training datasets, consisting both of 17 samples and validating on an independent experiment containing 32 samples. Peptide profiles were acquired by nano-scale liquid chromatography coupled to tandem mass spectrometry (nano LC-MS/MS).

Results

From the training datasets 53 peptides were found as potential biomarker candidates, predicting the fertilization outcome of 24 out of the 32 validation samples blindly (81.3% sensitivity, 68.8% specificity, AUC = 0.86). Seven potential biomarker peptides were identified. They were derived from: insulin-like growth factor binding protein-5, alpha-2-antiplasmin, complement component 3, inter-alpha-trypsin inhibitor heavy chain H1, serum albumin, protein diaphanous homolog 1 and plastin-3.

Conclusions

The MS-based comprehensive peptidomic approach carried out in this study, established a novel panel of potential biomarkers that present a promising predictive accuracy rate in fertilization outcome, and indicates FF as an interesting biomarker resource to improve IVF clinic routine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12953-016-0106-9) contains supplementary material, which is available to authorized users.

17β-estradiol prevents experimentally-induced oxidative damage to membrane lipids and nuclear DNA in porcine ovary

Estrogens, with their principle representative 17β-estradiol, contribute to the redox state of cells showing both pro- and antioxidative properties. In the ovary, being the main source of estrogens, maintaining balance between the production and detoxification of ROS is crucial. Whereas ovary estrogen concentration is difficult to estimate, its circulating concentration in women may reach the nanomolar level. The aim of the study was to evaluate the effects of 17β-estradiol on oxidative damage to membrane lipids (lipid peroxidation, LPO) and to nuclear DNA in the porcine ovary under basal conditions and in the presence of Fenton reaction (Fe(2+)+H2O2→Fe(3+)+(•)OH + OH(-)) substrates. Ovary homogenates and DNA were incubated in the presence of 17β-estradiol (1 mM-1 pM), without/with FeSO4 (30 μM) + H2O2 (0.5 mM). Malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA) concentration (LPO index) was measured spectrophotometrically. The concentration of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) (DNA damage index) was measured by HPLC. We observed that 17β-estradiol did not alter the basal level of oxidative damage, but reduced Fe(2+)+H2O2-induced oxidative damage to membrane lipids when ≥10 nM and to DNA at concentrations ≥1 nM. In the ovary at near physiological concentration, 17β-estradiol prevents experimentally induced oxidative damage. This suggests that under physiological conditions this hormone may contribute to protecting the ovary against oxidative damage.

Metabolite Profiling in the Pursuit of Biomarkers for IVF Outcome: The Case for Metabolomics Studies

Background. This paper presents the literature on biomarkers of in vitro fertilisation (IVF) outcome, demonstrating the progression of these studies towards metabolite profiling, specifically metabolomics. The need for more, and improved, metabolomics studies in the field of assisted conception is discussed. Methods. Searches were performed on ISI Web of Knowledge SM for literature associated with biomarkers of oocyte and embryo quality, and biomarkers of IVF outcome in embryo culture medium, follicular fluid (FF), and blood plasma in female mammals. Results. Metabolomics in the field of female reproduction is still in its infancy. Metabolomics investigations of embryo culture medium for embryo selection have been the most common, but only within the last five years. Only in 2012 has the first metabolomics investigation of FF for biomarkers of oocyte quality been reported. The only metabolomics studies of human blood plasma in this context have been aimed at identifying women with polycystic ovary syndrome (PCOS). Conclusions. Metabolomics is becoming more established in the field of assisted conception, but the studies performed so far have been preliminary and not all potential applications have yet been explored. With further improved metabolomics studies, the possibility of identifying a method for predicting IVF outcome may become a reality.

The redox state of recombinant human serum albumin and its optimal concentration for mouse embryo culture

Albumin has multiple physiological functions in embryo culture, such as a chelator of heavy metals, free radical scavenger, pH and osmotic regulator, a stabilizer, growth factor carrier, a surfactant, and a nutrient. However, the commercially available human serum albumin (HSA) products may not be completely safe since they could be contaminated with viruses and prions. Recombinant human serum albumin (rHSA) has been reported to be as efficient as commercial HSA for fertilization and embryo development. Despite the possible benefits of rHSA, it has not been widely used for embryo culture due to its high cost of production. Our objective was to analyze the redox state of different types of HSA products and rHSA to define oxidative status batch variations of HSA and rHSA and to evaluate the optimal concentration of rHSA for mouse embryo culture. The redox state of the HSA and rHSA used in embryo culture media was found to vary widely. Redox variations were found among different HSA batches as well as among rHSA batches. The highest blastocyst development and hatching rates were obtained with rHSA used at a concentration of 0.05 mg/mL. We showed that very low concentrations of rHSA were most favorable for advanced mouse embryo development in culture.