Improvement of implantation potential in mouse blastocysts derived from IVF by combined treatment with prolactin, epidermal growth factor and 4-hydroxyestradiol

Epigen enhances the developmental potential of in vitro fertilized embryos by improving cytoplasmic maturation

Numerous growth factors contribute to oocyte maturation and embryonic development in vivo; however, only a few are understood. One such factor is epigen, a new member of the epidermal growth factor (EGF) family that is secreted by the granulosa cells of immature oocytes. We hypothesized that epigen may play a role in oocyte maturation, specifically in the nuclear and cytoplasmic aspects. This study aimed to investigate the effects of epigen on porcine oocyte maturation and embryo development in vitro. In this study, three different concentrations of epigen (3, 6, and 30 ng/mL) were added to tissue culture medium-199 (TCM-199) during in vitro maturation of porcine oocytes. A control group that did not receive epigen supplementation was also included. Mature porcine oocytes were fertilized, and the resulting zygotes were cultured until day 7. The levels of intracellular glutathione (GSH) and reactive oxygen species (ROS) were measured in the in vitro matured oocytes. At the same time, the expression patterns of genes related to apoptosis were detected in day 7 blastocysts (BLs) using real-time quantitative PCR Apoptosis was detected by annexin-V assays in mature oocytes. Data were analyzed using ANOVA and Duncan's test on SPSS, and results are presented as mean ± SEM. The group that received 6 ng/mL epigen had a significantly lower rate of germinal vesicle breakdown (GVBD) than the control group without affecting the nuclear maturation among the experimental groups. Among the treatment groups, the 6 ng/mL epigen group showed significantly higher levels of intracellular GSH and lower ROS production. Supplementation with 6 ng/mL epigen significantly improved blastocyst (BL) formation rates compared to those in the control and 3 ng/mL groups. Additionally, the blastocyst expansion rate was significantly higher with epigen supplementation (6 ng/mL). In the fertilization experiment, the group supplemented with 6 ng/mL epigen exhibited significantly higher levels of monospermy and fertilization efficiency and lower levels of polyspermy than the control group. This study indicated that adding epigen at a concentration of 6 ng/mL can significantly enhance the developmental potential of porcine oocytes fertilized in vitro. Specifically, the study found that epigen improves cytoplasmic maturation, which helps prevent polyspermy and emulates monospermic penetration.

Arginine with leucine drives reactive oxygen species-mediated integrin α5β1 expression and promotes implantation in mouse blastocysts

The implantation rate of in vitro fertilization (IVF)-derived blastocysts after embryo transfer remains low, suggesting that the inadequate expression of specific proteins in culture-induced IVF-derived blastocysts contributes to low implantation rates. Therefore, treatment with appropriate regulation may improve the blastocyst implantation ability. This study demonstrated that the combination of l-arginine (Arg) and l-leucine (Leu) exerts distinct effects on IVF-derived mouse blastocysts. Arg with Leu promotes blastocyst implantation, whereas Arg alone decreases the blastocyst ability. Integrin α5β1 expression was increased in blastocysts treated with Arg and Leu. Arg with Leu also increased reactive oxygen species (ROS) levels and showed a positive correlation with integrin α5β1. Ascorbic acid, an antioxidant, decreased ROS and integrin α5β1 levels, which were elevated by Arg with Leu. Meanwhile, the mitochondrial membrane potential (ΔΨm) in blastocysts did not differ between treatments. Glutathione peroxidase (GPx) is involved in ROS scavenging using glutathione (GSH) as a reductant. Arg with Leu decreased GPx4 and GSH levels in blastocysts, and blastocysts with higher ROS levels had lower GPx4 and GSH levels. In contrast, Arg alone increased the percentage of caspase-positive cells, indicating that Arg alone, which attenuated implantation ability, was associated with apoptosis. This study revealed that elevated ROS levels induced by Arg with Leu stimulated integrin α5β1 expression, thereby enhancing implantation capacity. Our results also suggest that ROS were not due to increased production by oxidative phosphorylation, but rather to a reduction in ROS degradation due to diminished GPx4 and GSH levels.

The association between serum prolactin levels and live birth rates in non-PCOS patients: A retrospective cohort study

BACKGROUND AND OBJECTIVES

This paper aimed to analyze the relationship between baseline prolactin (PRL) levels and live birth rates (LBRs) in patients undergoing embryo transfer who did not have polycystic ovarian syndrome (PCOS) using a retrospective design. Patient(s): A total of 20,877 patients who had undergone IVF/intracytoplasmic sperm injection (ICSI) between December 2014 and December 2019.

MATERIALS AND METHODS

We examined the association between PRL concentrations and LBRs using multivariate regression analysis. In addition, a model for nonlinear relationships based on a two-part linear regression was developed.

RESULTS

Following adjustment for confounding factors, multivariate regression analysis confirmed a statistically significant correlation between serum PRL and LBR. Particularly, when blood PRL content was less than 14.8 ng/mL, there exists a positive relation between serum PRL and LBRs. In contrast, once PRL concentrations surpassed the inflection point at 14.8 ng/mL, a meaningful relationship could no longer be inferred between serum PRL and LBR.

CONCLUSIONS

Basal serum PRL levels were segmentally connected with LBRs.

Heterotopic pregnancy after assisted reproductive techniques with favorable outcome of the intrauterine pregnancy: A case report

BACKGROUND

Heterotopic pregnancy (HP) is a rare condition in which both ectopic and intrauterine pregnancies occur. HP is uncommon after natural conception but has recently received more attention due to the widespread use of assisted reproductive techniques (ART) such as ovulation promotion therapy.

CASE SUMMARY

Here, we describe a case of HP that occurred after ART with concurrent tubal and intrauterine singleton pregnancies. This was treated successfully with surgery to preserve the intrauterine pregnancy, resulting in the birth of a low-weight premature infant. This case report aims to increase awareness of the possibility of HP during routine first-trimester ultrasound examinations, especially in pregnancies resulting from ART and even if multiple intrauterine pregnancies are present.

CONCLUSION

This case alerts us to the importance of comprehensive data collection during regular consultations. It is important for us to remind ourselves of the possibility of HP in all patients presenting after ART, especially in women with an established and stable intrauterine pregnancy that complain of constant abdominal discomfort and also in women with an unusually raised human chorionic gonadotropin level compared with simplex intrauterine pregnancy. This will allow symptomatic and timeous treatment of patients with better results.

Prolactin Relationship with Fertility and In Vitro Fertilization Outcomes-A Review of the Literature

Hyperprolactinemia is a known cause of amenorrhea and infertility. However, there is an increasing body of evidence suggesting that prolactin is involved in multiple physiological aspects of normal reproduction. Thus, the present paper aims to review the current literature regarding the relationship between serum prolactin level and in vitro fertilization (IVF)/intracytoplasmic sperm injection outcome and the role of dopamine agonists treatment in IVF success. Moreover, the mechanisms by which prolactin may exert its role in fertility and infertility were summarized. Although not all studies agree, the available evidence suggests that higher prolactin levels in follicular fluid are associated with increased oocytes competence, but also with positive effects on corpus luteum formation and survival, endometrial receptivity, blastocyst implantation potential and survival of low-motile sperm. Transient hyperprolactinemia found in IVF cycles was reported in most of the studies not to be related to IVF outcome, although a few reports suggested that it may be associated with higher implantation and pregnancy rates, and better-cumulated pregnancy outcomes. Administration of dopamine agonists for hyperprolactinemia preceding IVF treatment does not seem to negatively impact the IVF results, while treatment of transient hyperprolactinemia during IVF might be beneficial in terms of fertilization rates and conception rates. Due to limited available evidence, future studies are necessary to clarify the optimal level of circulating prolactin in patients performing IVF and the role of dopamine agonist treatment.

Hypoxia-sensitive miRNA regulation via CRISPR/dCas9 loaded in hybrid exosomes: A novel strategy to improve embryo implantation and prevent placental insufficiency during pregnancy

Assisted reproductive techniques as a new regenerative medicine approach have significantly contributed to solving infertility problems that affect approximately 15% of couples worldwide. However, the success rate of an in vitro fertilization (IVF) cycle remains only about 20%-30%, and 75% of these losses are due to implantation failure (the crucial rate-limiting step of gestation). Implantation failure and abnormal placenta formation are mainly caused by defective adhesion, invasion, and angiogenesis. Placental insufficiency endangers both the mother's and the fetus's health. Therefore, we suggested a novel treatment strategy to improve endometrial receptivity and implantation success rate. In this strategy, regulating mir-30d expression as an upstream transcriptomic modifier of the embryo implantation results in modified expression of the involved genes in embryonic adhesion, invasion, and angiogenesis and consequently impedes implantation failure. For this purpose, "scaffold/matrix attachment regions (S/MARs)" are employed as non-viral episomal vectors, transfecting into trophoblasts by exosome-liposome hybrid carriers. These vectors comprise CRISPR/dCas9 with a guide RNA to exclusively induce miR-30d gene expression in hypoxic stress conditions. In order to avoid concerns about the fetus's genetic manipulation, our vector would be transfected specifically into the trophoblast layer of the blastocyst via binding to trophoblast Erb-B4 receptors without entering the inner cell mass. Additionally, S/MAR episomal vectors do not integrate with the original cell DNA. As an on/off regulatory switch, a hypoxia-sensitive promoter (HRE) is localized upstream of dCas9. The miR-30d expression increases before and during the implantation and placental insufficiency conditions and is extinguished after hypoxia elimination. This hypothesis emphasizes that improving the adhesion, invasion, and angiogenesis in the uterine microenvironment during pregnancy will result in increased implantation success and reduced placental insufficiency, as a new insight in translational medicine.

Upregulation of iNOS and phosphorylated eNOS in the implantation-induced blastocysts of mice

Purpose

This study aimed to examine expressions of iNOS and phosphorylated eNOS (p-eNOS) in implantation-induced blastocysts. We also examined the upstream of p-eNOS.

Methods

To address the protein expressions in implantation-induced blastocysts, we performed immunohistochemical analysis using a delayed implantation mouse model. Immunostaining for iNOS, p-eNOS, and p-Akt was done. To address the relationship between p-eNOS and p-Akt, activated blastocysts were treated with an Akt inhibitor, MK-2206.

Results

iNOS expression was at low levels in dormant blastocysts, whereas the expression was significantly increased in the activated blastocysts. Double staining of p-eNOS and p-Akt in individual blastocysts showed colocalization of p-eNOS and p-Akt of the trophectoderm. p-eNOS and p-Akt expressions were at low levels in dormant blastocysts, whereas both of them were significantly increased in the activated blastocysts. Both dormant and activated blastocysts showed significant positive correlations between p-eNOS and p-Akt. MK-2206 treatment for activated blastocysts showed that blastocysts with lower p-Akt had significantly lower p-eNOS levels.

Conclusions

iNOS and p-eNOS, Ca2+ independent NOS, are upregulated by E2 in the blastocysts during implantation activation. Furthermore, p-eNOS is upregulated in implantation-induced blastocysts downstream of p-Akt.

Evolutionary divergence of embryo implantation in primates

Implantation of the conceptus into the uterus is absolutely essential for successful embryo development. In humans, our understanding of this process has remained rudimentary owing to the inaccessibility of early implantation stages. Non-human primates recapitulate many aspects of human embryo development and provide crucial insights into trophoblast development, uterine receptivity and embryo invasion. Moreover, primate species exhibit a variety of implantation strategies and differ in embryo invasion depths. This review examines conservation and divergence of the key processes required for embryo implantation in different primates and in comparison with the canonical rodent model. We discuss trophectoderm compartmentalization, endometrial remodelling and embryo adhesion and invasion. Finally, we propose that studying the mechanism controlling invasion depth between different primate species may provide new insights and treatment strategies for placentation disorders in humans. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.

Effect of the addition of 4OHE2 and quercetin in culture media on ROS levels and gene expression in mouse blastocysts

AIMS

The main objective of this work is to elucidate whether Quercetin (Qc) and 4-Hidroxistradiol (4OHE2 ) decrease the level of reactive oxygen species (ROS) in in vitro obtained embryos and to analyse which genes are activated under the treatments that could explain this improvement.

METHODS

Oxidative stress was induced during embryo culture by H2 O2 treatment and ROS production was measured and compared with embryos treated with Qc or 4OHE2 . Gene expression was analysed by Q-PCR in control embryos obtained in utero (IU) or by IVF and compared with the levels found in embryos cultured with Qc or 4OHE2 to determine the effect of these compounds.

KEY RESULTS

Qc strongly reduces ROS levels in embryos after a treatment of 4h. On the contrary, 4OHE2 had no effect in reducing ROS levels in embryos. The addition of these molecules to the culture media upregulate several hypoxia-related genes when Qc is added to the culture media, and implantation-related genes when 4OHE2 is used.

CONCLUSIONS

Qc is a very strong antioxidant molecule that when used for short periods of time during culture can reduce ROS levels and improve embryo quality by activating antioxidant enzymes. 4OHE2 supplementation, despite having no effects in reducing ROS levels, acts directly in the molecular signalling implicated in the implantation process and could be also considered as a supplement for embryo culture during IVF.

IMPLICATIONS

Proper supplementation of the culture media could greatly improve the quality of embryos cultured in vitro , resulting in better results in IVF clinics.

Prolactin from Pluripotency to Central Nervous System Development

Prolactin (PRL) is a versatile hormone that exerts more than 300 functions in vertebrates, mainly associated with physiological effects in adult animals. Although the process that regulates early development is poorly understood, evidence suggests a role of PRL in the early embryonic development regarding pluripotency and nervous system development. Thus, PRL could be a crucial regulator in oocyte preimplantation and maturation as well as during diapause, a reversible state of blastocyst development arrest that shares metabolic, transcriptomic, and proteomic similarities with pluripotent stem cells in the naïve state. Thus, we analyzed the role of the hormone during those processes, which involve the regulation of its receptor and several signaling cascades (Jak/Mapk, Jak/Stat, and PI3k/Akt), resulting in either a plethora of physiological actions or their dysregulation, a factor in developmental disorders. Finally, we propose models to improve the knowledge on PRL function during early development.

Pluripotency and Growth Factors in Early Embryonic Development of Mammals: A Comparative Approach

The regulation of early events in mammalian embryonic development is a complex process. In the early stages, pluripotency, cellular differentiation, and growth should occur at specific times and these events are regulated by different genes that are expressed at specific times and locations. The genes related to pluripotency and cellular differentiation, and growth factors that determine successful embryonic development are different (or differentially expressed) among mammalian species. Some genes are fundamental for controlling pluripotency in some species but less fundamental in others, for example, Oct4 is particularly relevant in bovine early embryonic development, whereas Oct4 inhibition does not affect ovine early embryonic development. In addition, some mechanisms that regulate cellular differentiation do not seem to be clear or evolutionarily conserved. After cellular differentiation, growth factors are relevant in early development, and their effects also differ among species, for example, insulin-like growth factor improves the blastocyst development rate in some species but does not have the same effect in mice. Some growth factors influence genes related to pluripotency, and therefore, their role in early embryo development is not limited to cell growth but could also involve the earliest stages of development. In this review, we summarize the differences among mammalian species regarding the regulation of pluripotency, cellular differentiation, and growth factors in the early stages of embryonic development.

4-Hydroxyestradiol improves mouse embryo quality, epidermal growth factor-binding capability in vitro and implantation rates

Embryo implantation in the uterus is a critical step to achieve success following ART. Despite favorable uterine conditions, a great number of good quality embryos fail to implant, often for reasons that are unknown. Hence, improving the implantation potential of embryos is a subject of great interest. 4-Hydroxyestradiol (4-OH-E2), a metabolic product of estradiol produced by endometrial cells, plays a key role in endometrial-embryonic interactions that are necessary for implantation. Nonetheless, the effects of 4-OH-E2 on embryos obtained in vitro have not been yet described. This study was designed to determine whether culture media enriched in 4-OH-E2 could improve the quality and implantation rate of embryos obtained in vitro, using both in vitro and in vivo models. We also analyzed its effects on the epidermal growth factor (EGF)-binding capability of the embryos. Our results showed that the presence of 4-OH-E2 in the culture media of embryos during the morula to blastocyst transition increases embryo quality and attachment to endometrial cells in vitro. 4-OH-E2 can also improve viable pregnancy rates of mouse embryos produced in vitro, reaching success rates that are similar to those from embryos obtained directly from the uterus. 4-OH-E2 improved the embryos' ability to bind EGF, which could be responsible for the increased embryo implantation potential observed. Therefore, our results strongly suggest that 4-OH-E2 is a strong candidate molecule to supplement human IVF culture media in order to improve embryo implantation. However, further research is required before these findings can be translated with efficacy and safety to fertility clinics.

Mildly Higher Serum Prolactin Levels Are Directly Proportional to Cumulative Pregnancy Outcomes in in-vitro Fertilization/Intracytoplasmic Sperm Injection Cycles

Hyperprolactinemia has long been considered detrimental to fertility due to irregularity of ovulation. Whether mild hyperprolactinemia should be corrected before initiating an in-vitro fertilization/intracytoplasmic sperm injection cycle (IVF/ICSI) has not been determined; this study aimed to examine how different levels of prolactin affect IVF outcomes. A total of 3,009 patients with basal prolactin level <50 ng/mL undergoing IVF/ICSI cycles for tubal or male factors were recruited in this study. Patients diagnosed with anovulation owing to polycystic ovarian syndrome or hyperandrogenism were ruled out. Pregnancy outcomes were compared between patients with basal prolactin levels higher or lower than the median level of prolactin (16.05 ng/mL). Multifactor analyses were carried out among four subgroups depending on different prolactin levels. Repeated-measures analysis of variance was used to explore the relationship between the ascending trend of prolactin levels over ovarian stimulation and the corresponding cumulative pregnancy outcomes. There were significantly higher numbers of oocytes (9 vs. 8, P = 0.013) and embryos (6 vs. 5, P = 0.015) in patients with basal prolactin higher than 16.05 ng/mL. Basal prolactin higher than 30 ng/mL was positively related to cumulative clinical pregnancy, and a level higher than 40 ng/mL was a good indicator for the cumulative live birth rate. Throughout ovarian stimulation, the prognosis of pregnancy improved with increasing prolactin levels. Patients with better cumulated pregnancy outcomes had significantly higher prolactin levels as well as a profoundly increasing trend during the stimulating process than those who did not conceive. For patients who underwent the gonadotropin-releasing hormone agonist long protocol IVF/ICSI treatment, a slightly higher prolactin level during the controlled ovarian hyperstimulation protocol was a positive indicator for cumulated pregnancy/live birth rates.

Tubulointerstitial nephritis antigen-like 1 deficiency alleviates age-dependent depressed ovulation associated with ovarian collagen deposition in mice

PURPOSE

This study aimed to examine whether the Tinagl1 might be associated with ovulation in aged females and reproductive age-associated fibrosis in the stroma of the ovary.

METHODS

To address the ovulatory ability and quality of ovulated oocytes, we induced ovulation by treatment with equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) followed by in vitro fertilization. We also performed Picrosirius Red (PSR) staining to evaluate ovarian collagen deposition.

RESULTS

As compared to ovulation in 8- to 9-month-old Tinagl1flox/flox mice, the number of ovulated oocytes from Tinagl1flox/flox mice decreased in an age-dependent manner in mice more than 10-11 months old, whereas the ovulated oocyte numbers in Tinagl1 -/- mice decreased significantly at 14-15 months. In vitro fertilization followed by embryo culture demonstrated the normal developmental potential of Tinagl1-null embryos during the preimplantation period. PSR staining indicated that collagen was found throughout the ovarian stroma in an age-dependent manner in Tinagl1flox/flox females, whereas those distributions were delayed to 14-15 months in Tinagl1 -/- females. This timing was consistent with the delayed timing of age-related decline of ovulation in Tinagl1 -/- females.

CONCLUSIONS

The alleviation of age-associated depression of ovulation was caused by delayed ovarian collagen deposition in Tinagl1-null female mice.

Transient Sperm Starvation Improves the Outcome of Assisted Reproductive Technologies

To become fertile, mammalian sperm must undergo a series of biochemical and physiological changes known as capacitation. These changes involve crosstalk between metabolic and signaling pathways and can be recapitulated in vitro. In this work, sperm were incubated in the absence of exogenous nutrients (starved) until they were no longer able to move. Once immotile, energy substrates were added back to the media and sperm motility was rescued. Following rescue, a significantly higher percentage of starved sperm attained hyperactivated motility and displayed increased ability to fertilize in vitro when compared with sperm persistently incubated in standard capacitation media. Remarkably, the effects of this treatment continue beyond fertilization as starved and rescued sperm promoted higher rates of embryo development, and once transferred to pseudo-pregnant females, blastocysts derived from treated sperm produced significantly more pups. In addition, the starvation and rescue protocol increased fertilization and embryo development rates in sperm from a severely sub-fertile mouse model, and when combined with temporal increase in Ca²⁺ ion levels, this methodology significantly improved fertilization and embryo development rates in sperm of sterile CatSper1 KO mice model. Intracytoplasmic sperm injection (ICSI) does not work in the agriculturally relevant bovine system. Here, we show that transient nutrient starvation of bovine sperm significantly enhanced ICSI success in this species. These data reveal that the conditions under which sperm are treated impact post-fertilization development and suggest that this “starvation and rescue method” can be used to improve assisted reproductive technologies (ARTs) in other mammalian species, including humans.

Exogenous growth factors do not affect the development of individually cultured murine embryos

PURPOSE

The objective of this study was to evaluate the effects of multiple growth factors on the development of individually cultured murine embryos.

METHODS

Embryos produced by in vitro fertilization using in vitro (IVM) or in vivo (IVO) matured oocytes from three strains of mice (CF1, Swiss Webster, B6D2F1) were cultured individually (10 μl) in the absence (control) or presence of growth factors (paf, epidermal growth factor [EGF], insulin-like growth factor 1 [IGF-1], and granulocyte-macrophage colony-stimulating factor [GM-CSF]). Blastocyst formation, hatching, and blastocyst cell numbers (trophectoderm, inner cell mass, and total) were evaluated on days 4 and 5 of culture. Post-hatching development of CF1 IVO embryos was also evaluated in vitro and in vivo.

RESULTS

The presence of growth factors did not improve the proportion of embryos forming blastocysts or initiating hatching for any of the types of embryos tested. The only significant (P < 0.05) effect of growth factors was a decrease in the proportion of embryos that formed blastocysts by day 5 in CF1 IVM embryos. The presence of growth factors also did not affect blastocyst cell numbers. For CF1 IVO embryos, the presence of growth factors during culture did not affect the proportion of embryos that attached to fibronectin-coated dishes, the size of the resulting outgrowths, or in vivo development following transfer.

CONCLUSION

Combinations of paf, EGF, GM-CSF, and IGF-1 did not improve development of murine embryos cultured individually in a sequential medium containing a defined protein source.