Effect of resveratrol supplementation during culture on the quality and cryotolerance of bovine in vitro produced embryos

Co-culture with adipose mesenchymal stem cells promotes Blastocyst formation and gene expression in embryos from aged mice

Recent studies have highlighted the positive effects of co-culturing embryos with stem cells on embryo development in various mammalian systems. Stem cells secrete numerous factors, including cytokines, growth factors, and microRNAs, which promote embryo development. However, the impact of stem cells on the development of embryos derived from aged mice's oocytes remains poorly understood. This study evaluated the co-culture effects of adipose tissue-derived mesenchymal stem cells (ADMSCs) on zygotes, focusing on the developmental potential of fertilized embryos. Embryo quality was assessed through staining techniques to measure trophectoderm (TE), inner cell mass (ICM), and total blastocyst cell numbers during in vitro culture. Results demonstrated that ADMSC co-culture significantly improved zygote cleavage and blastocyst development rates, particularly in embryos derived from aged mice. Enhanced implantation and post-implantation potential were observed in embryos from both young and aged mice. Notably, co-culture increased TE, ICM, and total blastocyst cell numbers in aged mice-derived embryos without inducing apoptosis in blastocysts. Gene expression analysis revealed upregulation of OCT4 and G6PDH, associated with pluripotency and glucose metabolism, particularly in embryos from aged mice, while the heat stress marker HSP70 showed no significant changes. These findings demonstrate the potential of ADMSC co-culture as a beneficial protocol for improving embryo development. These findings from this study could offer an important basis for future mechanistic studies in this area.

Developmental stage specific effect of Mito-TEMPO on the expression outline of antioxidant genes, ROS balance and cryo-resilience of bovine IVP embryos

In vitro culture impairs mitochondrial metabolism of IVP derived bovine embryos resulting in accumulation of reactive oxygen species. Recently, the antioxidant Mito-TEMPO has attracted attention due to its capability to accumulate within mitochondria. In order to investigate the potential of Mito-TEMPO to improve quality of IVP derived embryos, this study analyzed the developmental stage specific effect of Mito-TEMPO on developmental capacity, ROS balance, expression outline of antioxidative genes and cryo-resilience of blastocysts. In three subsequent experiments Mito-TEMPO (1 μM) was added either to the maturation medium (MTM), the culture medium (MTC) or to both the maturation medium and the culture medium (MTMC). Concerning cleavage- and blastocyst rates, no effect of Mito-TEMPO supplementation could be detected, although MTM and/or MTC groups revealed significantly (p < 0.05) lower levels of ROS. Expression outline of antioxidative genes under study was not affected in MTM group, whereas down-regulation of the proapoptotic gene BAX was observed in MTM as well as MTMC groups. Moreover, Mito-TEMPO significantly affected expression outline of genes with antioxidative functions within mitochondria (SOD2, GPX1, GSTA4) in MTC and/or MTMC groups and peroxisomes (CAT) in MTMC group. In contrast, expression of genes acting predominately outside mitochondria (NFE2L2 and PRDX1) was not affected. Of high impact, the present study revealed for the first time greatly improved reexpansion and hatching rates of bovine vitrified-warmed embryos as a consequence of supplementation of Mito-TEMPO to culture media. Collectively, the present study successfully proved that Mito-TEMPO alleviates negative effects of the in vitro culture environment in bovine pre-implantation embryos.

Factors Affecting the Success of Ovum Pick-Up, In Vitro Production and Cryopreservation of Embryos in Cattle

Increasing global demand for animal proteins warrants improved productivity by genetic selection of superior cattle and faster dissemination of genetics. Availability of more progeny for genomic selection should maximize chances of identifying animals with desirable traits and increase selection pressure. OPU and IVP of embryos using these oocytes will substantially increase calves produced compared to conventional embryo transfer (ET). The OPU-IVP technology not only supports genetic improvement but also contributes to reducing environmental impacts of livestock production systems by improving efficiency and optimizing resources, aligning with the Sustainable Development Goals of the United Nations. However, there are several factors influencing the success of OPU-IVP. This review is focused on these factors and the impacts of in vitro culture conditions on the lipid content of embryos and potential role of L-carnitine, a lipolytic agent, on developmental competence of IVP embryos. The documented effects of L-carnitine and current knowledge regarding regulation of the Hippo signaling pathway suggest that supplementation of embryo culture media with L-carnitine will increase post-thaw survival of IVP embryos and their subsequent developmental competence by regulating lipid metabolism, production of reactive oxygen species, and Hippo signaling. Therefore, this review highlights current advancements in the field of OPU-IVP and potential areas for refining culture conditions to yield developmentally competent embryos that survive cryopreservation procedures.

RA33, an analogue of resveratrol, improves the development of in vitro-fertilized bovine embryos

Oxidative stress is an undesirable effect of in vitro culture, which requires antioxidant supplementation. This study investigated the analogue of resveratrol (RA33) as an alternative to resveratrol, an antioxidant molecule, for the in vitro culture of in vitro-fertilized bovine embryos. The effect of different concentrations of RA33 on embryo development was evaluated and a comparison between RA33 and resveratrol was performed. The cleavage rate was higher (P < 0.05) with 2.5 μM (69.0 ± 4.4%) than at 0, 0.1 or 0.5 μM RA33 (62.1 ± 2.0%, 60.7 ± 5.9% and 56.7 ± 5.8%, respectively). The blastocyst rates on days 7 and 8 post-fertilization with 2.5 μM RA33 (19.4 ± 3.3% and 24.6 ± 3.3%, respectively) were higher (P < 0.05) than for 0 μM (12.4 ± 2.5% and 15.2±2.5%, respectively). When 2.5 μM RA33 was compared with 0.5 μM resveratrol, similar (P > 0.05) cleavage and blastocyst rates were found between them, but the cleavage rate was higher (P < 0.05) in the control (80.8 ± 3.4%) than for the resveratrol treatment (76.4 ± 3.6%). The numbers of apoptotic cells and the apoptotic index were lower (P < 0.05) with RA33 (6.5 ± 0.6 cells and 6.4 ± 0.7%, respectively) and resveratrol (5 ± 0.8 cells and 5.5 ± 1.0%, respectively) than in the control group (9.8 ± 1.2 cells and 8.9 ± 1.1%, respectively). In conclusion, RA33 can enhance the preimplantation development of in vitro-fertilized bovine embryos and be an alternative to resveratrol in embryo culture medium.

Resveratrol enhanced mitochondrial recovery from cryopreservation-induced damages in oocytes and embryos

BACKGROUND

Mitochondria play a crucial role in nuclear maturation, fertilization, and subsequent embryo development. Cryopreservation is an important assisted reproductive technology that is used worldwide for humans and domestic animals. Although mitochondrial quantity and quality are decisive factors for successful development of oocytes and embryos, cryopreservation induces mitochondrial dysfunction. Upon thawing, the damaged mitochondria are removed, and de novo synthesis occurs to restore the function of mitochondria. Resveratrol, 3,5,4'-trihydroxystilbene, is a polyphenolic antioxidant that has versatile target proteins, among which sirtuin-1 (SIRT1) is a key regulator of in mitochondrial biogenesis and degradation.

METHODS

The present study is a literature review focusing on experiments involving the hypothesis that the activation of mitochondrial biogenesis and degradation following cryopreservation and warming by resveratrol may help mitochondrial recovery and improve oocyte and embryo development.

MAIN FINDINGS AND CONCLUSION

Resveratrol improves oocyte maturation and development and upregulates mitochondrial biogenesis and degradation. When vitrified-warmed embryos are treated with resveratrol, it helps in mitochondrial regulation and recovery of embryos from cryopreservation-induced damage.

CONCLUSION

Resveratrol treatment is a possible countermeasure against cryopreservation-induced mitochondrial damage.

Morphometry of bovine blastocysts produced in vitro in culture media with antioxidants cysteamine or oily extract of Lippia origanoides

ABSTRACT This study aimed to evaluate the ultrastructural morphometry of bovine embryos produced in vitro grown at different concentrations of antioxidants. After in vitro maturation and fertilization, the presumptive zygotes were assigned into five treatments. T1) without the addition of any antioxidants (negative control); T2) addition of 50μM/mL cysteamine; and T3, T4 and T5) adding 2.5μg/mL, 5.0μg/mL or 10.0μg/mL of the antioxidants derived from the oily extract from Lippia origanoides, respectively. On D7 of culture, the embryos in the blastocyst stage were fixed and prepared for electron transmission microscopy. These were evaluated for the proportion of cytoplasm-to-nucleus, cytoplasm-to-mitochondria, cytoplasm-to-vacuoles, cytoplasm-to-autophagic vacuoles and cytoplasm-to-lipid droplets. Blastocysts cultured in media containing oily extract of Lippia origanoides presented morphological characteristics such as high cell:mitochondria ratio and low cell:vacuoles and cell:autophagic vacuole ratio, possibly been morphological indicators of embryonic quality. Inner cell mass (ICM) from blastocysts cultured in media without any antioxidants had the highest cell:vacuole ratio. Similar results were found in the trophectoderm (TE) cells of blastocysts from treatment 2. Embryo culture media supplemented with antioxidants derived from Lippia origanoides oil produced embryos with a higher cytoplasmic proportion of organelles, such as mitochondria. Also, treatments without any antioxidants or with the addition of cysteamine presented cytoplasmic vacuolization, a characteristic related to production of poor-quality embryos.

Enhanced Cryoprotective Effect of Melatonin and Resveratrol by Coencapsulation: Improved In Vitro Development of Vitrified-Warmed Mouse Germinal Vesicle Oocytes

Oocyte vitrification, as a vital step in reproductive medicine, is strongly associated with lower development caused by cryodamaging factors, such as oxidative stress. In this study, we evaluated the antioxidative synergistic effects of Melatonin (Mel) and Resveratrol (RES) coencapsulated by solid lipid nanocarriers (SLNs) against the pure antioxidant combination (Mel+RES). In this research, the formation of Mel+RES-SLN was confirmed by Fourier-transformed infrared spectroscopy. The average mean diameter, size distribution, polydispersity index, and zeta potential of particles were measured by Zetasizer, and the morphology was evaluated by scanning electron microscopy. In addition, the encapsulation efficiency (EE%) or drug loading capacity (DL%) of the nanocapsule was determined by spectrophotometric methods. Germinal vesicle (GV)-stage oocytes harvested from 6- to 12-week-old female NMRI mice were randomly divided into seven groups for in vitro studies. In these groups, (0, 10^-12 M + 0.5 μM, 10^-9 M + 2 μM, or 10^-6 M + 10 μM) of Mel+RES/Mel+RES-SLN were added into vitrification media. After thawing, oocytes were matured, fertilized, and cultured for 3 days. Extra/intracellular reactive oxygen species (ROS) levels were measured in in vitro maturation medium after 24 hours. Our results revealed a significant improvement in the normal morphology of warmed GV-stage oocytes, GV breakdown (GVBD) rate, Metaphase II (MII)-stage oocyte formation, fertilization rate, early embryo development, and a significant reduction in intra/extracellular ROS level when vitrification media was supplemented with the lowest Mel+RES-SLN concentration. In vitro studies also demonstrated that the highest concentration of Mel+RES-SLN was safe, without a detrimental effect on embryonic development upon treatment. In conclusion, the lowest concentration of Mel+RES-SLN supplementation in GV-stage oocyte vitrification media improved maturation, fertilization, and embryo development rate and decreased extra/intracellular ROS level through an enhanced/controlled intracellular penetration compared to the pure Mel+RES.

Ceratonia siliqua (Carob) extract improved in vitro development of vitrified-warmed mouse germinal vesicle oocytes: assessment of possible mechanism

Oocyte banking is a vital step for safekeeping and spreading genetic resources of animals. It is also used for fertility preservation of human. Oocyte vitrification is closely related to the lower developmental competence which includes the cryo-injury arisen during vitrification. The aim of the present study was to evaluate the maturation, embryonic development and production of reactive oxygen species (ROS) of mice oocytes following the supplementation vitrification media with different concentrations of Ceratonia siliqua (carob) extracts. In this experimental study, germinal vesicle oocytes collected from 8 to 10 week-old female NMRI mice (30-40 gr) were randomly divided into six groups of vitrification media supplemented with 0 (control), 5, 10, 20, 30 and 50 µg/ml C. siliqua. After thawing, oocytes were put in an in vitro maturation medium (IVM) (α-MEM: Alpha Minimum Essential Medium). 3-4 and 24 h (hr) later, the oocyte nuclear maturity was checked. Standard in vitro fertilization was performed on the matured oocytes (MII), and embryonic development was followed. Extra- and intra-cellular ROS was measured in IVM medium after 24 h of oocyte incubation. The addition of 20 and 30 μg/ml C. siliqua extract to vitrification media improved normal morphology of warmed germinal vesicle (GV) oocytes, rate of germinal vesicle break down (GVBD), and metaphase 2 (MII) oocyte formation significantly (p < 0.05). Fertilization rate, (embryonic development to 2 cells stage, 4-8 cells stage, and > 8 cells stage increased in the 30 μg/ml C. siliqua group significantly (p < 0.05). Furthermore, supplementation of 30 μg/ml C. siliqua in vitrification media significantly decreased extra- and intra-cellular of ROS as well as embryonic fragmentation (p < 0.05). In conclusion, supplementation of GV oocyte vitrification media with carob extract improved maturation, fertilization, and embryonic development rate and decreased extra- and intra-cellular ROS levels.

The Role of Resveratrol in Mammalian Reproduction

Resveratrol is one of the most investigated natural polyphenolic compounds and is contained in more than 70 types of plants and in red wine. The widespread interest in this polyphenol derives from its antioxidant, anti-inflammatory and anti-aging properties. Several studies have established that resveratrol regulates animal reproduction. However, the mechanisms of action and the potential therapeutic effects are still unclear. This review aims to clarify the role of resveratrol in male and female reproductive functions, with a focus on animals of veterinary interest. In females, resveratrol has been considered as a phytoestrogen due to its capacity to modulate ovarian function and steroidogenesis via sirtuins, SIRT1 in particular. Resveratrol has also been used to enhance aged oocyte quality and as a gametes cryo-protectant with mainly antioxidant and anti-apoptotic effects. In males, resveratrol enhances testes function and spermatogenesis through activation of the AMPK pathway. Furthermore, resveratrol has been supplemented to semen extenders, improving the preservation of sperm quality. In conclusion, resveratrol has potentially beneficial effects for ameliorating ovarian and testes function.

Methodological approaches for vitrification of bovine oocytes

Numerous factors affect vitrification success and post-thaw development of oocytes after in vitro fertilization. Therefore, elaboration of an optimal methodology ensuring higher cryotolerance of oocytes and subsequent blastocyst yield is still of great interest. This paper describes and evaluates critical factors affecting the success of oocyte vitrification. In particular, an appropriate oocyte stage such as maturation status (germinal vesicle stage, metaphase II stage), presence/absence of cumulus cells before vitrification, and the effect of follicle size, as well as different culture systems and media for in vitro production of embryos, the types and concentrations of cryoprotectants, and cooling and warming rates at vitrification are considered. Special attention is paid to various cryocarriers used for low-volume vitrification, which ensures safe storage of oocytes/embryos in liquid nitrogen and their successful post-thaw recovery. At the end, we focussed on how age of oocyte donors (heifers, cows) influences post-thaw development. This review summarizes results of recently published studies describing different methodologies of cryopreservation and post-thaw oocyte development with the main focus on vitrification of bovine oocytes.

Effect of pterostilbene on development, equatorial lipid accumulation and reactive oxygen species production of in vitro-produced bovine embryos

The pterostilbene (PT) molecule is a phytoalexin with a reducing effect on reactive oxygen species (ROS) and with a capacity to block lipogenesis. However, the potential reducing effects of PT on equatorial lipid accumulation and ROS have not yet been elucidated for in vitro-derived bovine embryos. The present study evaluated the effects of concentrations of 3, 1, 0.33, 0.11 μM PT, and a vehicle group on the percentage of cleaved embryos, embryos with more than 6 cells, percentage of blastocyst on Day 7 and 8, percentage of transferable embryos on Day 7, the cell count and relative concentration of lipids. In the second experiment, the effects of 0.33 μM PT and a vehicle group within two different O₂ environments (5% and 20%) were evaluated for ROS generation and the percentage of Day 8 blastocysts. In the first experiment, no significant differences were found between the treatments with PT and the vehicle group (p > .05) concerning the percentage of cleaved embryos and embryos with more than 6 cells. Lipid reduction was observed in the groups treated with PT versus the vehicle group (p < .05). The vehicle group showed a higher rate of blastocyst production on Days 7 and 8 (p < .05) and an increase in the percentage of transferable embryos on Day 7 compared to the PT treatment groups (p < .05). Cell counts were not significantly different between treatments with PT and the vehicle group (p > .05). In the second experiment, the O₂ concentration did not significantly affect ROS generation (p > .05); however, the groups treated with PT (0.33 μM) had a reduction in ROS (p < .05). The O₂ concentration also did not significantly affect the rate of blastocyst production on Day 8 (p = .7696). Future research should be conducted to ascertain whether the reduction of lipids could enhance the cryopreservation and post-thaw viability of PT-treated embryos.

Nicotinamide-induced mouse embryo developmental defect rescued by resveratrol and I-CBP112

Cell cycle of mouse embryo could be delayed by nicotinamide (NAM). Histone H3 lysine 56 (H3K56ac) acetylation plays an important role in mammalian genomic stability and the function of this modification in mouse embryos is not known. Hence, we designed to study the effects of NAM-induced oxidative stress on the developmental ability of mouse embryos, on the acetylation of H3K56ac and the possible functions of this modification related to mouse embryo development. Treatment with NAM (10, 20, or 40 mmol/L for 24 or 48 hr) during in vitro culture significantly decreased developmental rate of blastocyst (24 hr: 90.2 vs. 81.2, 43.2, and 18.2, with p > .05, p < .01, respectively; 48 hr: 89.3 vs. 53.2%, 12.1%, and 0% with p < .05, respectively). NAM treatment (20 mmol/L) for 6 and 31 hr resulted in increased intracellular reactive oxygen species levels in two-cell embryos, and apoptotic cell numbers in blastocysts. Resveratrol (RSV) and I-CBP112 rescued the 20 mmol/L NAM-induced embryo developmental defects. RSV and I-CBP112 increased the level of Sirt1 and decreased the level of H3K56ac induced by NAM in two-cell embryos (p < .05). These data suggest that NAM treatment decreases the expression of Sirt1, which induces high levels of H3K56 acetylation that may be involved in oxidative stress-induced mouse embryo defects, which can be rescued by RSV and I-CBP112.

Effects of Supplementation with Natural Antioxidants on Oocytes and Preimplantation Embryos

For most infertile couples, in vitro fertilization (IVF) represents the only chance to conceive. Given the limited success of IVF procedures, novel approaches are continuously tested with the aim of improving IVF outcomes. Growing attention is devoted today to the potential benefit of natural antioxidants in the optimization of infertility treatments. This review summarizes current data in this context, focusing on both experimental studies on oocytes/embryos and clinical trials on antioxidants supplementation. Based on information gained from experimental studies, antioxidant supplementation may have beneficial effects on IVF outcomes in terms of quality and cryotolerance of in vitro produced embryos, together with positive effects on in vitro maturation oocytes and on early embryonic development. Unfortunately, from the clinical side, there is a paucity of evidence favoring the protective qualities of antioxidants. Among the antioxidants considered, coenzyme Q10 may be regarded as one of the most promising for its positive role in rescuing the oxidative stress-induced damages, but further data are needed. It is concluded that further trials are necessary to characterize the potential clinical value of antioxidants in IVF treatments.

Change in plasma sirtuin 1 level by injection into uterus of resveratrol in Korean cattle

Bovine embryonic development is closely associated with mitochondrial biogenesis, which is regulated by the sirtuin 1 (SIRT1). Resveratrol, which is a type of natural phenol produced by several plants and used as a dietary supplement, is the activator of SIRT1. Although it has been reported that resveratrol increased SIRT1 level in in vitro bovine blastocysts, there are no in vivo reports on the change in the plasma SIRT1 level in cows. Therefore, we investigated the change in the level of plasma SIRT1 by injecting different concentrations of resveratrol into the uterus of Korean cattle heifer. The level of plasma SIRT1 in the 1.0 μM resveratrol-injected group was the highest among all groups (P < 0.05). Although the level of plasma SIRT1 increased on days 7, 9, and 14 in the resveratrol-injected group, the level of plasma SIRT1 in the control group decreased. When 1.0 µM resveratrol was directly injected into the uterus of cows during artificial insemination, a pregnancy rate was 21.0% higher than that in the control group. In conclusion, our results identified that the level of plasma SIRT1 was increased by direct injection of resveratrol and improved conception rate by injection into uterus of cow during artificial insemination.

Rescue of vitrified-warmed bovine mature oocytes by short-term recovery culture with resveratrol

Resveratrol, a well-known antioxidant, has been reported to protect mouse metaphase-II (M - II) stage oocytes from vitrification injuries when used as a treatment during a series of vitrification processes. The present study was conducted to investigate whether short-term treatment of post-warm bovine mature oocytes with resveratrol can increase blastocyst formation rate following in vitro fertilization and culture. Bovine denuded M - II oocytes were vitrified-warmed using Cryotop® or nylon mesh (pore size = 37 μm) as a cryodevice. The post-warm oocytes were treated for 2 h with 1 μM resveratrol in recovery culture medium. The resveratrol treatment had no harmful influence on morphological survival and cleavage rate of the oocytes vitrified-warmed with Cryotop® or nylon mesh. In the Cryotop® vitrification series, blastocyst formation rate of resveratrol-treated post-warm oocytes (39.0%) was not significantly different from that of non-treated post-warm oocytes (31.7%). However in the nylon mesh vitrification series, there was a significant increase in the blastocyst yield (42.4% vs. 31.3%, P < 0.05) when post-warm oocytes were treated with resveratrol. Blastocyst yield from fresh control oocytes was 49%. Levels of reactive oxygen species were comparable between post-warm and fresh control M - II oocytes, and decreased in oocytes after recovery culture with resveratrol. Mitochondrial activity of post-warm oocytes was restored to the pre-vitrification level during the recovery culture regardless of resveratrol supplementation. Thus, short-term recovery culture with resveratrol can rescue bovine M - II oocytes vitrified-warmed on a nylon mesh cryodevice.

Effects of resveratrol, granulocyte-macrophage colony-stimulating factor or dichloroacetic acid in the culture media on embryonic development and pregnancy rates in aged mice

The success rate of assisted reproductive technology is closely correlated with maternal age. Reproductive aging pathologies are frequently caused by impaired DNA repair, genomic instability, and mitochondrial dysfunction. Several reports have shown that resveratrol can prevent age-related diseases by improving mitochondrial function. Improved blastocyst development and mitochondrial output by dichloroacetic acid (DCA) supplementation were reported in aged mice. Granulocyte-macrophage colony-stimulating factor (GM-CSF) has significant effects on implantation rates in women with previous miscarriages. Therefore, this study was conducted to observe how those compounds influence the developmental and the reproductive potential of aged oocytes. BDF1 female mice at 58-62 weeks old were used for this study. MII oocytes were fertilized and cultured in MRC media supplemented with or without resveratrol (0.5 μM), GM-CSF (2 ng/ml) or DCA (1.0 mM). The addition of resveratrol, GM-CSF or DCA tended to increase blastocyst development and pregnancy rates. Supplementation with resveratrol significantly increased the pregnancy and implantation rates (p < 0.05). Moreover, resveratrol decreased reactive oxygen species production and increased mitochondrial membrane potential. These results suggest that the addition of resveratrol can increase pregnancy outcomes in women of advanced maternal age.

Resveratrol supplementation promotes recovery of lower oxidative metabolism after vitrification and warming of in vitro-produced bovine embryos

Although vitrification is the current method of choice for oocyte and embryo cryopreservation, it may have detrimental effects on reduction-oxidation status and mitochondrial activity. The aim of this study was to evaluate the effect of supplementing invitro culture (IVC) media and/or vitrification solutions with the antioxidant resveratrol on active mitochondria, mitochondrial superoxide production and lipid peroxidation. Abattoir-derived oocytes were matured and fertilised invitro using standard procedures. Following IVF (21h later), zygotes were cultured in IVC medium supplemented with 0 or 0.5µM resveratrol. On Day 7, blastocysts were vitrified using the Cryotech Vitrification Kit (Cryo Tech Laboratory) with or without 0.5µM resveratrol. After warming, active mitochondria, mitochondrial superoxide production and lipid peroxidation were evaluated using Mito Tracker Green FM, MitoSOX Red and BODIPY581/591 C11 staining respectively. The vitrification-warming process significantly increased active mitochondria and mitochondrial superoxide production in bovine embryos (P<0.05, ANOVA). The addition of 0.5µM resveratrol to the IVC medium or vitrification solutions significantly attenuated the increase in active mitochondria (P<0.05), but not in mitochondrial superoxide production, whereas embryos cultured and vitrified with resveratrol showed the highest values for both parameters (P<0.05). Regarding lipid peroxidation, no significant differences were detected between treatments. In conclusion, resveratrol supplementation of IVC medium or vitrification solutions contributes to recovery of an embryo's 'quieter' state (i.e. lower oxidative metabolism) after vitrification. However, supplementation of both solutions with resveratrol seemed to have a pro-oxidant effect.

Effects of resveratrol on in vitro maturation of porcine oocytes and subsequent early embryonic development following somatic cell nuclear transfer

As a natural plant-derived antitoxin, resveratrol possesses several pharmacological activities. This study aimed to evaluate the effects of resveratrol addition on nuclear maturation, oocyte quality during in vitro maturation (IVM) of porcine oocytes and subsequent early embryonic development following somatic cell nuclear transfer (SCNT). Our experiments showed that the treatment of porcine oocytes with 5 µM resveratrol during IVM resulted in the highest rate of the first polar body extrusion. Treatment of oocytes with resveratrol had no influence on cytoskeletal dynamics, whereas it significantly increased glucose uptake ability compared to the control oocytes. Oocytes matured with 5 μM resveratrol displayed significantly lower intracellular reactive oxygen species (ROS) levels and higher relative mRNA expression levels of the genes encoding such antioxidant enzymes as catalase (CAT) and superoxide dismutase 1 (SOD1). In addition, resveratrol also prevented onset and progression of programmed cell death in porcine oocytes, which was confirmed by significant upregulation of the anti-apoptotic B-cell lymphoma 2 (BCL-2) gene and significant downregulation of the pro-apoptotic BCL2-associated X (BAX) gene. Furthermore, the blastocyst rates and the blastocyst cell numbers in cloned embryos derived from the oocytes that had matured in the presence of 5 μM resveratrol were significantly increased. In conclusion, supplementation of IVM medium with 5 μM resveratrol improves the quality of porcine oocytes by protecting them from oxidative damage and apoptosis, which leads to the production of meiotically matured oocytes exhibiting enhanced developmental potential following SCNT.

Resveratrol addition to in vitro maturation and in vitro culture media enhances developmental competence of sheep embryos

The present study aimed to examine the effects of adding different concentrations of resveratrol during in vitro culture (IVC) alone and during both in vitro maturation (IVM) and IVC on ovine blastocyst yield and quality. Therefore, this study was conducted in two separate experiments. The first experiment was carried out to test the effect of different concentrations of resveratrol (0, 0.1, 0.25, 0.5, 2.0, and 5.0 μM) in the IVC medium on cleavage, morula, developmental potential of blastocyst, and total cell number (TCN) of the embryos. Addition of 0.25 and 0.5 μM of resveratrol during IVC significantly enhanced morula and blastocyst rates as compared with other groups (P < 0.05). Also, supplementation of the IVC medium with 0.5 μM of resveratrol had beneficial effects on trophectoderm cells (TE), inner cell mass (ICM), and TCN of blastocysts. In the second experiment, the same concentrations of resveratrol (0, 0.1, 0.25, 0.5, 2.0, and 5.0 μM) were applied during IVM and IVC. Therefore, oocytes were matured in vitro in the presence of different concentrations of resveratrol for 22-24 h. After in vitro fertilization, presumptive zygotes were cultured in media containing 0, 0.1, 0.25, 0.5, 2.0, and 5.0 μM of resveratrol for 8 d. No significant difference was found in the percentage of oocytes developed to MII (0, 0.1, 0.25, 0.5, and 2.0 μM of resveratrol), but the percentage of oocytes developed to MII were significantly lower in 5.0 μM of resveratrol in comparison with other groups. Addition of 0.5 μM of resveratrol to the maturation and culture media significantly increased morula and blastocyst rates compared with other groups (P < 0.05). However, a too high concentration of resveratrol (5.0 μM) during IVM and IVC decreased cleavage, morula, and blastocyst rates compared with low concentrations (P < 0.05). Treatment with 0.5/0.5 μM of resveratrol during IVM/IVC significantly improved the TE, ICM, and TCN of blastocysts. In conclusion, sequential treatment with 0.5 μM of resveratrol during IVM and IVC and during IVC alone improved the developmental competence of oocytes, which was reflected in higher blastocyst rates and TCN of blastocysts.

Mild hypothermia promotes the viability of in vitro-produced bovine blastocysts and their transcriptional expression of the cold-inducible transcription factor Rbm3 during in vitro culture

In this study, we evaluated the effects of holding in vitro-produced bovine blastocysts under mild hypothermia (33°C or 35°C), by examining viability and hatching rates of day 7 blastocysts (day 0: in vitro fertilization) cultured for 6 days and transcriptional expression of cold-inducible transcription factors Cirp and Rbm3, implicated in mild hypothermia-induced cellular protection against various types of stress. In the normothermic control (38.5°C), viability of the embryos decreased rapidly after day 10, and most samples were degenerated on day 13. However, mild hypothermia, particularly at 33°C, resulted in maintenance of high embryonic survival rates until day 13 (77.1% on day 13) and significant increases in transcriptional expression of Rbm3 in day 11 embryos compared with those at 38.5°C. Thus, our results suggested that upregulation of Rbm3 may occur in response to mild hypothermia in many bovine embryos, providing insights into the effects of mild hypothermia on embryo quality.

Antioxidant activity of oily extract obtained from Lippia origanoides improves the quality of bovine embryos produced in vitro

ABSTRACT The aim of this study was to evaluate the supplementation of embryo culture medium with antioxidant obtained from oily extract of Lippia origanoides on in vitro blastocyst development and quality. Oocytes collected from slaughterhouse ovaries were matured and fertilized in vitro following standard laboratory procedures. Zygotes were cultured in SOF medium supplemented according to the following treatments: T1 embryo culture medium without antioxidant supplementation; T2)50μM/mL Cysteamine; T3)2.5μg/mL; T4)5.0μg/mL and T5)10.0μg/mL of antioxidant obtained from oily extract of Lippia origanoides. On the seventh day of culture, the blastocysts were fixed and evaluated for apoptosis rates, number of total cell and inner cell mass cells by means of the TUNEL Test. The use of antioxidants during cultivation did not increase (P> 0.05) the final blastocyst production rate. The treatments T2, T3, T4 and T5 had the lowest (P< 0.05) apoptotic indexes (4.5±1.1%, 8.4±2.5%, 3.4±1.1% and 5.5±0.9%, respectively) when compared to T1 treatment (10.0±1.4%). The number of inner cell mass did not differ (P> 0.05) among embryos from different treatments. The addition of antioxidant obtained from oily extract of Lippia origanoides reduces the apoptosis rate and improves the quality without increasing the total in vitro production of bovine embryos.

Effect of resveratrol on vitrified in vitro produced bovine embryos: Recovering the initial quality

Although vitrification is the current routine method for human embryo cryopreservation, it may cause detrimental effects. The aim of this study was to evaluate the effect of supplementing in vitro culture (IVC) media and/or vitrification solutions (VS) with Resveratrol on the presence of apoptotic markers, reactive oxygen species (ROS) level, glutathione (GSH) content and relative gene abundance. Abattoir-derived oocytes were matured and fertilized in vitro according to a standard procedure. Zygotes were cultured in IVC medium supplemented with or without 0.5 μM Resveratrol (C^R, C^- respectively). On day 7, blastocysts were vitrified using the minimum volume vitrification method supplementing VS with (C^-V^R, C^RV^R) or without (C^-V^-, C^RV^-) 0.5 μM Resveratrol. After warming, embryonic quality parameters were evaluated. Survival rates were significantly lower in C^RV^R group compared with C^RV^- group, but no differences in hatching rate were observed between groups. Vitrification/warming process did not alter total cell number or the presence of apoptotic or dead cells, but C^RV^- and C^RV^R groups presented a significant increase in dead cells (P < 0.05 by ANOVA). Resveratrol supplementation in VS (C^-V^R) restored GSH content (P < 0.05) to the level found in the C^R group. Vitrification/warming process significantly increased the expression of FOXO3A, PNPLA2, BCL2L1 and BAX genes (P < 0.05). Resveratrol addition to IVC medium or VS partially compensated this increase for FOXO3A and PNPLA2 (P < 0.05) but not for BCL2L1 and BAX. In conclusion, supplementation of IVC media or VS with 0.5 μM resveratrol may help embryos to partially restore the initial quality they had before the cryopreservation process.

Enzymatic activity of mouse group X-sPLA2 improves in vitro production of preimplantation bovine embryos

Assisted reproductive technologies (ART) are widely used for both humans and domestic animals. In bovine species, in vitro embryo production is increasingly used and significant efforts are being made to optimize media and culture conditions. Phospholipase A2 (PLA2) are lipolytic enzymes that hydrolyze glycerophospholipids to produce free fatty acids and lysophospholipids that have been found to be critical for many biological processes. Mouse group X secreted PLA₂ (mGX) is abundant in the male reproductive tract and its use during sperm capacitation has been shown to improve in vitro production of viable embryos in a mouse model. Here, we examined its effect in the bovine species, testing the impact of mGX on the three steps involved in vitro production of preimplantation embryos: oocyte maturation, fertilization and preimplantation development. We found that incubating cumulus oocyte complexes (COC) or gametes with mGX resulted in increased blastocyst hatching and blastocyst production, respectively. The increases of embryo production induced by the phospholipase mGX were not observed for the catalytically inactive mutant H48Q-mGX, suggesting that these effects require the enzymatic activity of mGX. We also tested bGIB, a bovine homolog of mGX. bGIB failed to improve blastocyst production, underlining the high specificity of mGX. In conclusion, the results presented show that the effects of mGX are not restricted to the mouse model and that it is potent in the bovine species as well. This result strengthens the potential of mGX as a "pro-fertility drug" for mammalian reproduction.

p66Shc is associated with hydrogen peroxide-induced oxidative stress in preimplantation sheep embryos

The low efficiency of in vitro embryo production is associated with oxidative stress induced by suboptimal culture conditions. p66Shc is a 66-kDa protein of the ShcA (Src homologous-collagen homolog) adaptor protein family, which is involved in signaling pathways involved in oxidative stress regulation, apoptosis induction, and aging. However, the functional role of p66Shc during the preimplantation development of sheep embryos is not understood. Our results showed that early-cleavage (≤28 hr) embryos had a higher developmental potential than late-cleavage (>28 hr) embryos. The poor quality of these late-cleavage embryos was associated with increased the transcripts and protein of p66Shc and decreased mitochondrial activity. In addition, exogenous hydrogen peroxide-induced oxidative stress significantly increased p66Shc protein abundance and suppressed embryonic development, which was ameliorated by antioxidant treatment. Notably, oxidative stress induced the nuclear localization of p66Shc and phosphorylated (Ser-36) p66Shc. Collectively, these observations suggest that p66Shc may be playing an important role in the regulation of oxidative stress during the preimplantation development of sheep embryos.

Likelihood of pregnancy after the transfer of embryos derived from follicle aspiration and in vitro embryo production sessions with different relative efficiencies

The aim of the present study was to evaluate the likelihood of pregnancy of in vitro-produced (IVP) embryos from batches with distinct relative efficiencies. Data were retrospectively analyzed from 605 transvaginal ultrasonic-guided follicle aspiration sessions (OPU) followed by in vitro embryo production (IVEP) and 2456 fresh embryo transfers (ET), performed between 2008 and 2012 in individuals of the Gir (dairy Bos indicus) breed. The OPU and IVEP were performed using standard procedures by a single group of technicians at the same laboratory facility. Records were stratified into quartiles (I to IV) according to the total of cumulus-oocytes complexes (COC) produced per donor, or in percentile ranges (0%-25%, 26%-50%, 51%-75%, and 76%-100%) for endpoints related to COC quality or efficiency of embryo production. Pregnancy per embryo transfer (P/ET) was compared among quartiles or ranges using the chi-squared test. Donors producing a greater number of total COC (quartile I) also had more viable and grade I COC, and a greater number of embryos than donors ranked in quartiles II, III or IV, respectively (P < 0.0001). Nevertheless, P/ET did not differ (P > 0.05) among embryos produced by donors ranked in Quartiles I to IV. Similarly, there was no difference (P > 0.05) in P/ET for embryos derived from OPU sessions with a relatively greater or lesser percentage of viable or Grade I COC. Cleavage and blastocyst rates within each IVEP batch had no effect (P > 0.05) on P/ET. In conclusion, data suggest that there is no relationship among oocyte yield after OPU, or efficiency of IVEP, and the likelihood of pregnancy after ET of fresh IVP embryos.

The Potential of Nanotechnology in Medically Assisted Reproduction

Reproductive medicine is a field of science which searches for new alternatives not only to help couples achieve pregnancy and preserve fertility, but also to diagnose and treat diseases which can impair the normal operation of the reproductive tract. Assisted reproductive technology (ART) is a set of methodologies applied to cases related to infertility. Despite being highly practiced worldwide, ART presents some challenges, which still require special attention. Nanotechnology, as a tool for reproductive medicine, has been considered to help overcome some of those impairments. Over recent years, nanotechnology approaches applied to reproductive medicine have provided strategies to improve diagnosis and increase specificity and sensitivity. For in vitro embryo production, studies in non-human models have been used to deliver molecules to gametes and embryos. The exploration of nanotechnology for ART would bring great advances. In this way, experiments in non-human models to test the development and safety of new protocols using nanomaterials are very important for informing potential future employment in humans. This paper presents recent developments in nanotechnology regarding impairments still faced by ART: ovary stimulation, multiple pregnancy, and genetic disorders. New perspectives for further use of nanotechnology in reproductive medicine studies are also discussed.

Modification of mitochondrial function, cytoplasmic lipid content and cryosensitivity of bovine embryos by resveratrol

Resveratrol is a potent activator of NAD-dependent deacetyltransferase sirtuin-1 (SIRT1) and affects lipid metabolism and ATP generation in somatic cells. In the present study, the effects of supplementing culture medium with resveratrol on lipid metabolism, ATP generation, and cryosensitivity of bovine in vitro produced embryos were investigated. Bovine early cleaved-stage embryos were cultured in medium containing 0 or 0.5 µM resveratrol for 1 or 5 days. Resveratrol treatment for both 1 day and 5 days increased the expression levels of SIRT1 and phosphorylated AMP-activated protein kinase (pAMPK) in the embryos. Furthermore, resveratrol treatment was effective to increase ATP generation and reduce lipid content of the embryos. The effects of resveratrol treatment were diminished by the SIRT1 inhibitor “EX527”, and the reduced lipid content was reversed by treatment with etomoxir (a potent inhibitor of beta-oxidation). Blastocysts developed after resveratrol treatment showed low levels reactive oxygen species and increased cryotolerance. These results demonstrate that resveratrol improves in vitro development of bovine embryos, while reducing cytoplasmic lipid content through activation of beta-oxidation, thereby effective for production of bovine blastocysts with enhanced cryotolerance.

Increasing of blastocyst rate and gene expression in co-culture of bovine embryos with adult adipose tissue-derived mesenchymal stem cells

PURPOSE

Despite advances in the composition of defined embryo culture media, co-culture with somatic cells is still used for bovine in vitro embryo production (IVEP) in many laboratories worldwide. Granulosa cells are most often used for this purpose, although recent work suggests that co-culture with stem cells of adult or embryonic origin or their derived biomaterials may improve mouse, cattle, and pig embryo development.

MATERIALS AND METHODS

In experiment 1, in vitro produced bovine embryos were co-cultured in the presence of two concentrations of bovine adipose tissue-derived mesenchymal cells (b-ATMSCs; 10³ and 10⁴ cells/mL), in b-ATMSC preconditioned medium (SOF-Cond), or SOF alone (control). In experiment 2, co-culture with 10⁴ b-ATMSCs/mL was compared to the traditional granulosa cell co-culture system (Gran).

RESULTS

In experiment 1, co-culture with 10⁴ b-ATMSCs/mL improved blastocyst rates in comparison to conditioned and control media (p < 0.05). Despite that it did not show difference with 10³ b-ATMSCs/mL (p = 0.051), group 10⁴ b-ATMSCs/mL yielded higher results of blastocyst production. In experiment 2, when compared to group Gran, co-culture with 10⁴ b-ATMSCs/mL improved not only blastocyst rates but also quality as assessed by increased total cell numbers and mRNA expression levels for POU5F1 and G6PDH (p < 0.05).

CONCLUSIONS

Co-culture of bovine embryos with b-ATMSCs was more beneficial than the traditional co-culture system with granulosa cells. We speculate that the microenvironmental modulatory potential of MSCs, by means of soluble substances and exosome secretions, could be responsible for the positive effects observed. Further experiments must be done to evaluate if this beneficial effect in vitro also translates to an increase in offspring following embryo transfer. Moreover, this study provides an interesting platform to study the basic requirements during preimplantation embryo development, which, in turn, may aid the improvement of embryo culture protocols in bovine and other species.

Crocetin improves the quality of in vitro-produced bovine embryos: Implications for blastocyst development, cryotolerance, and apoptosis

The aim of this work was to assess the effect of supplementation of bovine culture medium with the natural antioxidant crocetin on in vitro blastocyst development and quality. This was evaluated as cryotolerance, apoptosis index, and total cells number and allocation. Abattoir-derived oocytes were matured and fertilized in vitro according to standard procedure. Twenty hours after IVF, presumptive zygotes were cultured in synthetic oviduct fluid medium, supplemented with 0, 1, 2.5, and 5 μM crocetin (experiment 1) at 39 °C under humidified air with 5% CO2, 7% O2, and 88% N2. On Day 7, embryo yields were assessed and the blastocysts were vitrified by Cryotop method in 16.5% ethylene glycol, 16.5% DMSO, and 0.5 M sucrose. Finally, blastocysts produced on Day 8 in the absence (control) and presence of 1 μM crocetin were used for terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling and differential staining to evaluate, respectively, the apoptotic rate and the allocation of cells into inner cell mass (ICM) and trophectoderm (TE) lineages (experiment 2). Embryo development was higher in the 1 μM crocetin group compared to the control, both in terms of total embryo output (37.7 ± 4.2%, 52.9 ± 6.3%, 40.9 ± 7.6%, and 42.4 ± 8.7%, respectively, with 0, 1, 2.5, and 5 μM; P < 0.01) and grade 1 and 2 blastocysts (33.6 ± 4.9%, 46.1 ± 7.3%, 37.8 ± 7.9%, and 39.4 ± 7.9%, respectively, with 0, 1, 2.5, and 5 μM; P < 0.05). Moreover, the percentage of fast-developing embryos increased in 1 μM crocetin group compared to the control (23.4 ± 4.7%, 32.7 ± 6.6%, 27.2 ± 6.6%, and 30.1 ± 7.2%, respectively, with 0, 1, 2.5, and 5 μM; P < 0.05). In addition, the enrichment of culture medium with 1 μM crocetin improved embryo cryotolerance compared to the control, as indicated by higher hatching rates recorded after 48 hours postwarming culture (46.5% vs. 60.4%; P < 0.05). Furthermore, 1 μM crocetin decreased both the average number (9.9 ± 0.4 vs. 7.1 ± 0.3) and the percentage of apoptotic cells (7.1 ± 0.4 vs. 4.2 ± 0.2) in blastocysts compared to the control (P < 0.01). However, no differences were recorded in the average number of ICM, TE, and total cells between 1 μM crocetin and control groups. In conclusion, the enrichment of bovine culture medium with 1 μM crocetin increased both blastocyst yield and quality, as indicated by the improved chronology of embryo development, increased resistance to cryopreservation, and reduced incidence of apoptosis.

A natural product, resveratrol, protects against high-glucose-induced developmental damage in chicken embryo

Resveratrol, a famous plant-derived polyphenolic phytoalexin, has been considered to play physiological roles such as antioxidative, neuroprotective, and anticancer effects in adults. However, its antioxidative activity and neuroprotective effect were seldom discussed in the embryonic system. In this study, the effect of resveratrol on chicken embryo development under high glucose and its underlying mechanism of resveratrol were investigated. High glucose administrated to chicken embryo at embryonic Day 1 induced stillbirth, growth retardation, and impaired blood vessel development on yolk sac. However, resveratrol supplementation before glucose exposure showed significant effect on decreasing the death rate, developmental damage, and vessel injury. In addition, oxidative stress was caused by high-glucose exposure, and resveratrol could rescue this high-glucose-induced oxidative stress. Moreover, the neural developmental marker paired box 3 was significantly decreased by high glucose and recovered by resveratrol. Cell cycle-regulated gene expression was also intervened by resveratrol. This study had found an association between resveratrol and hyperglycemia-induced embryonic damage, which suggested a potential protective effect of resveratrol on gestational diabetes.

Stress signaling in mammalian oocytes and embryos: a basis for intervention and improvement of outcomes

Oocytes and early stage embryos are highly sensitive to variation in diverse exogenous factors such as temperature, osmolarity, oxygen, nutrient restriction, pH, shear stress, toxins, amino acid availability, and lipids. It is becoming increasingly apparent that many such factors negatively affect the endoplasmic reticulum, protein synthesis and protein processing, initiating ER stress and unfolded protein responses. As a result, ER stress signaling serves as a common mediator of cellular responses to diverse stressors. In oocytes and embryos, this leads to developmental arrest and epigenetic changes. Recent studies have revealed that preventing ER stress or inhibiting ER stress signaling can preserve or even enhance oocyte and embryo developmental potential. This review examines ER stress signaling, how it arises, how it affects oocytes and embryos, and how its occurrence can be managed or prevented.