Melatonin delivery by nanocapsules during in vitro bovine oocyte maturation decreased the reactive oxygen species of oocytes and embryos

Magnetic-Assisted Control of Eggs and Embryos via Zona Pellucida-Linked Nanoparticles

Eggs and embryo manipulation is an important biotechnological challenge to enable positioning, entrapment, and selection of reproductive cells to advance into a new era of nature-like assisted reproductive technologies. Oviductin (OVGP1) is an abundant protein in the oviduct that binds reversibly to the zona pellucida, an extracellular matrix that surrounds eggs and embryos. Here, the study reports a new method coupling OVGP1 to magnetic nanoparticles (NP) forming a complex (NPOv). NPOv specifically surrounds eggs and embryos in a reversible manner. Eggs/embryos bound to NPOv can be moved or retained when subjected to a magnetic force, and interestingly only mature-competent eggs are attracted. This procedure is compatible with normal development following gametes function, in vitro fertilization, embryo development and resulting in the birth of healthy offspring. The results provide in vitro proof-of-concept that eggs and embryos can be precisely guided in the absence of physical contact by the use of magnets.

Antioxidant sericin averts the disruption of oocyte-follicular cell communication triggered by oxidative stress

Antioxidants are free radical scavengers that increase oocyte quality and improve female fertility by suppressing oxidative stress. However, the related mechanisms remain unclear. The present study was designed to examine whether a reduction of oxidative stress from using the antioxidant sericin led to expanded cumulus cell (CC)-oocyte communication and oocyte developmental acquisition in a bovine model. We found that cumulus-oocyte complexes (COCs) matured in the presence of sericin showed a significantly increased oocyte meiotic maturation rate (P < 0.01) and accelerated subsequent blastocyst formation, as more blastocysts were found at the hatched stage (P < 0.05) compared to that in the control group. In contrast to the control group, sericin suppressed H2O2 levels in COCs, resulting in a markedly enhanced CC-oocyte gap junction communication index and number of transzonal projections, which were preserved until 18 h of oocyte maturation. These findings indicate that sericin reduces disruption of oocyte-follicular cell communication induced by oxidative stress. Sericin consistently increased intra-oocyte glutathione (GSH) levels and reduced oocyte H2O2 levels (P < 0.05), both of which were ablated when GSH synthesis was inhibited by buthionine sulfoximide (an inhibitor of GSH synthesis). Furthermore, the inhibition of GSH synthesis counteracted the positive effects of sericin on subsequent embryo developmental competence (P < 0.01). Intra-oocyte GSH levels were positively associated with blastocyst development and quality. These outcomes demonstrate new perspectives for the improvement of oocyte quality in assisted reproductive technology and may contribute to developing treatment strategies for infertility and cancer.

Immunolocalization of melatonin receptor type 1 in the sheep ovary and involvement of the PI3K/Akt/FOXO3a signaling pathway in the effects of melatonin on survival and in vitro activation of primordial follicles

This study characterized the expression of melatonin receptor type 1 (MT₁ ) protein in sheep ovaries, evaluated melatonin effects on primordial follicle survival and development after in vitro culture of ovarian tissue and verified the possible involvement of the phosphatidylinositol-3-kinase/protein kinase B/forkhead box O3a (PI3K/Akt/FOXO3a) pathway in the melatonin actions. Ovine ovarian fragments were cultured in α-modified minimum essential medium alone (α-MEM⁺ ) or supplemented with 100, 500, or 1000 pg/ml melatonin for 7 days. PI3K inhibition was performed through pretreatment of ovarian fragments with LY294002. Thereafter, immunohistochemistry was performed to evaluate the expression of cleaved caspase-3, Akt, phosphorylated-Akt, and phosphorylated-FOXO3a (p-FOXO3a). The immunohistochemical localization of the MT₁ receptor protein was documented in sheep preantral and antral follicles. After in vitro culture, 100 pg/ml melatonin showed higher follicular survival and activation than α-MEM⁺ and other melatonin concentrations. After PI3K inhibition, there was an increase in cleaved caspase-3-positive follicles, and a decrease in the primordial follicle activation, Akt phosphorylation, and nuclear exclusion of p-FOXO3a. In conclusion, MT₁ receptor protein is present in the sheep ovary. Furthermore, 100 pg/ml melatonin maintains survival and stimulates activation of primordial follicles through the PI3K/Akt/FOXO3a signaling pathway after in vitro culture of sheep ovarian tissue.

Beneficial Effect of Selenium Doped Carbon Quantum Dots Supplementation on the in vitro Development Competence of Ovine Oocytes

Background

After the synthesis of selenium doped carbon quantum dots (Se/CDs) via a step-by-step hydrothermal synthesis method with diphenyl diselenide (DPDSe) as precursor, the beneficial effects of Se/CDs’ supplementation on the in vitro development competence of ovine oocytes were firstly investigated in this study by the assay of maturation rate, cortical granules’ (CGs) dynamics, mitochondrial activity, reactive oxygen species (ROS) production, epigenetic modification, transcript profile, and embryonic development competence.

Results

The results showed that the Se/CDs’ supplementation during the in vitro maturation (IVM) process not only enhanced the maturation rate, CGs’ dynamics, mitochondrial activity and embryonic developmental competence of ovine oocytes, but remarkably decreased the ROS production level of ovine oocytes. In addition, the expression levels of H3K9me3 and H3K27me3 in the ovine oocytes were significantly up-regulated after the Se/CDs’ supplementation, in consistent with the expression levels of 5mC and 5hmC. Moreover, 2994 up-regulated differentially expressed genes (DEGs) and 846 repressed DEGs were found in the oocytes after the Se/CDs’ supplementation. According to the analyses of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), these DEGs induced by the Se/CDs’ supplementation were positively related to the progesterone mediated oocyte maturation and mitochondrial functions. And these remarkably up-regulated expression levels of DEGs related to oocyte maturation, mitochondrial function, and epigenetic modification induced by the Se/CDs’ supplementation further confirmed the beneficial effect of Se/CDs’ supplementation on the in vitro development competence of ovine oocytes.

Conclusion

The Se/CDs prepared in our study significantly promoted the in vitro development competence of ovine oocytes, benefiting the extended research about the potential applications of Se/CDs in mammalian breeding technologies.

Exogenous Melatonin in the Culture Medium Does Not Affect the Development of In Vivo-Derived Pig Embryos but Substantially Improves the Quality of In Vitro-Produced Embryos

Cloned and transgenic pigs are relevant human disease models and serve as potential donors for regenerative medicine and xenotransplantation. These technologies demand oocytes and embryos of good quality. However, the current protocols for in vitro production (IVP) of pig embryos give reduced blastocyst efficiency and embryo quality compared to in vivo controls. This is likely due to culture conditions jeopardizing embryonic homeostasis including the effect of reactive oxygen species (ROS) influence. In this study, the antioxidant melatonin (1 nM) in the maturation medium, fertilization medium, or both media was ineffective in enhancing fertilization or embryonic development parameters of in vitro fertilized oocytes. Supplementation of melatonin in the fertilization medium also had no effect on sperm function. In contrast, the addition of melatonin to the embryo culture medium accelerated the timing of embryonic development and increased the percentages of cleaved embryos and presumed zygotes that developed to the blastocyst stage. Furthermore, it increased the number of inner mass cells and the inner mass cell/total cell number ratio per blastocyst while increasing intracellular glutathione and reducing ROS and DNA damage levels in embryos. Contrarily, the addition of melatonin to the embryo culture medium had no evident effect on in vivo-derived embryos, including the developmental capacity and the quality of in vivo-derived 4-cell embryos or the percentage of genome-edited in vivo-derived zygotes achieving the blastocyst stage. In conclusion, exogenous melatonin in the embryo culture medium enhances the development and quality of in vitro-derived embryos but not in in vivo-derived embryos. Exogenous melatonin is thus recommended during embryo culture of oocytes matured and fertilized in vitro for improving porcine IVP efficiency.

Effects of EGF and melatonin on gene expression of cumulus cells and further in vitro embryo development in bovines

Despite previous research demonstrating the benefits of including growth factors and antioxidants to maturation medium to support embryo production, to date the effect of epidermal growth factor (EGF) and melatonin (Mel) on oocyte competency has not been studied. This study supplemented in vitro maturation (IVM) medium with EGF (10 ng/ml) and Mel (50 ng/ml) alone, or in combination, and evaluated cumulus cell (CC) gene expression and the development and quality of parthenogenetic blastocysts. No differences in CC gene expression levels indicative of developmental potential were found among the treatment groups. Antioxidant gene CuZnSOD was significantly (P < 0.05) decreased in CCs from the Mel group. Moreover, blastocyst rates on day 7 were significantly increased in EGF or Mel (P < 0.05), but not EGF+Mel. Significant decrease (P < 0.05) in GPX1, CuZnSOD, SLC2A1 and HSPA1A (P = 0.07) mRNA levels was observed in blastocysts from the Mel group. OCT4 gene expression was significantly increased (P < 0.05) in EGF+Mel and confirmed using immunofluorescence. Our results indicate that, despite the lack of changes of competence-related genes in CCs, IVM medium supplemented with Mel improved the culture environment sufficiently, resulting in improved blastocysts. Moreover, EGF and Mel combined during maturation increased OCT4 gene and protein expression in blastocysts, indicating its potential for stem cells.

Effect of E-64 Supplementation during In Vitro Maturation on the Developmental Competence of Bovine OPU-Derived Oocytes

Recovery of bovine oocytes using the ovum pick-up (OPU) technique offers the advantage of rapid genetic improvement through propagation of desired genes from animals with high genetic qualities. However, the developmental competence of OPU-derived immature oocytes remains relatively poor. We previously found that cathepsin B gene expression and activity are increased in poor quality oocytes and embryos compared to good quality ones. In this study, we investigated the effect of E-64 (cathepsin B inhibitor) supplementation during in vitro maturation (IVM) on the developmental competence of OPU-derived immature oocytes and the quality of the produced blastocysts. Our results showed that supplementation of IVM medium with E-64 significantly improved the developmental competence of OPU-derived immature oocytes as evidenced by the significant increase of the blastocyst rate. Importantly, the presence of E-64 during IVM also significantly improved blastocyst quality by increasing the total cell number and decreasing the percentage of TUNEL positive cells. These results indicate that E-64 supplementation during IVM is a promising tool to improve the efficiency of OPU-IVF program by improving the developmental competence of OPU-derived immature oocytes.

The effect of Tempo and MitoTEMPO on oocyte maturation and subsequent embryo development in bovine model

Reactive oxygen species (ROS) are one of the factors which reduces oocyte quality and viability of the in vitro produced embryos. Oocyte mitochondria are the major source of ROS production, hence, and the addition of mitochondrion-specific antioxidants could be suggested to minimize the damage caused by ROS during culture. MitoTEMPO, a targeted mitochondrial antioxidant, is formed by conjugating TEMPO to triphenylphosphonium and has an activity like that of superoxide dismutase. It can pass through lipid bilayers easily and accumulate selectively in mitochondria. The goal of this study was to investigate the effects of MitoTEMPO and its non-targeted form, TEMPO, on the developmental competence of bovine oocytes. Accordingly, oocytes were cultured in maturation medium supplemented with either five mM TEMPO (T5) or one μM MitoTEMPO (M1), or T5 + M1 (MT15), or without the antioxidants (C). Nuclear maturation to metaphase II (MII) stage, intracellular glutathione (GSH) content and ROS levels in matured oocytes were analyzed. In addition, cleavage after in vitro fertilization, and blastocyst rates, total cell number in blastocysts as well as the relative abundance of apoptosis-related genes (BAX and BCL2) in blastocysts were determined. Results revealed that the proportion of oocytes at the MII stage, embryos at the blastocyst stage and total cell number in blastocysts increased significantly in the M1 group compared to the C and T5 groups. The levels of intracellular GSH and ROS in oocytes decreased in the M1 group than in the C group (P < 0.05). The expression level of the pro-apoptotic gene (BAX) reduced in blastocysts from the M1 group in comparison to the C and T5 groups (P < 0.05). On the other hand, the expression level of anti-apoptotic gene (BCL2) in obtained blastocysts was not affected by TEMPO and MitoTEMPO. However, the ratio of BAX/BCL2 in blastocysts from the M1 and MT15 groups decreased significantly compared to the C group. These findings suggest that MitoTEMPO can mitigate the adverse effects of oxidative stress on the developmental competence of bovine oocytes.

Benefits and challenges of nanomaterials in assisted reproductive technologies

Assisted reproductive technology (ART) have contributed to preserve fertility in humans and to increase multiplication of genetically superior animals. Despite being highly practiced worldwide, ART presents some challenges, especially because gametes and embryos are kept in vitro for a variable period of time, and the oxidative stress in vitro can have negative impact on oocyte competence and embryo development. Nanotechnology needs to be considered to help overcome some of those impairments, since it can provide strategies to deliver antioxidants and hormones to gametes and embryos in vitro. The application of nanotechnology to ART can allow the development of new protocols using nanomaterials to improve in vitro oocyte competence and embryo production. This review discusses the applicability of nanomaterials to improve sperm selection, to deliver antioxidants and hormones to preantral follicles, oocytes, and embryos in vitro, as well as the concerns about using nanotechnology in ART.

A pilot study investigating a novel particle-based growth factor delivery system for preimplantation embryo culture

STUDY QUESTION

Can vascular endothelial growth factor (VEGF)-loaded silica supraparticles (V-SPs) be used as a novel mode of delivering VEGF to the developing preimplantation embryo in vitro?

SUMMARY ANSWER

Supplementation of embryo culture media with V-SPs promoted embryonic development in a manner equivalent to media supplemented with free VEGF.

WHAT IS KNOWN ALREADY

VEGF is a maternally derived growth factor that promotes preimplantation embryonic development in vitro. However, its use in clinical media has limitations due to its low stability in solution.

STUDY DESIGN, SIZE, DURATION

This study was a laboratory-based analysis utilising a mouse model. V-SPs were prepared in vitro and supplemented to embryonic culture media. The bioactivity of V-SPs was determined by analysis of blastocyst developmental outcomes (blastocyst development rate and total cell number).

PARTICIPANTS/MATERIALS, SETTING, METHODS

SPs were loaded with fluorescently labelled VEGF and release kinetics were characterised. Bioactivity of unlabelled VEGF released from V-SPs was determined by analysis of embryo developmental outcomes (blastocyst developmental rate and total cell number) following individual mouse embryo culture in 20 µl of G1/G2 media at 5% oxygen, supplemented with 10 ng/ml recombinant mouse VEGF in solution or with V-SPs. The bioactivity of freeze-dried V-SPs was also assessed to determine the efficacy of cryostorage.

MAIN RESULTS AND THE ROLE OF CHANCE

VEGF release kinetics were characterised by an initial burst of VEGF from loaded spheres followed by a consistent lower level of VEGF release over 48 h. VEGF released from V-SPs resulted in significant increases in total blastocyst cell number relative to the control (P < 0.001), replicating the effects of medium freely supplemented with fresh VEGF (P < 0.001). Similarly, freeze dried V-SPs exerted comparable effects on embryonic development (P < 0.05).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

In this proof of principle study, the effects of V-SPs on embryonic development were only analysed in a mouse model.

WIDER IMPLICATIONS OF THE FINDINGS

These findings suggest that SPs represent a novel method by which a targeted dose of therapeutic agents (e.g. bioactive VEGF) can be delivered to the developing in vitro embryo to promote embryonic development, an approach that negates the breakdown of VEGF associated with storage in solution. As such, V-SPs may be an alternative and effective method of delivering bioactive VEGF to the developing in vitro embryo; however, the potential use of V-SPs in clinical IVF requires further investigation.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the University of Melbourne. The authors have no conflict of interest to declare.

Nanotechnology and Reproductive Management of Farm Animals: Challenges and Advances

Reproductive efficiency of farm animals has central consequences on productivity and profitability of livestock farming systems. Optimal reproductive management is based on applying different strategies, including biological, hormonal, nutritional strategies, as well as reproductive disease control. These strategies should not only guarantee sufficient reproductive outcomes but should also comply with practical and ethical aspects. For example, the efficiency of the biological- and hormonal-based reproductive strategies is mainly related to several biological factors and physiological status of animals, and of nutritional strategies, additional factors, such as digestion and absorption, can contribute. In addition, the management of reproductive-related diseases is challenged by the concerns regarding the intensive use of antibiotics and the development of antimicrobial resistant strains. The emergence of nanotechnology applications in livestock farming systems may present innovative and new solutions for overcoming reproductive management challenges. Many drugs (hormones and antibiotics), biological molecules, and nutrients can acquire novel physicochemical properties using nanotechnology; the main ones are improved bioavailability, higher cellular uptake, controlled sustained release, and lower toxicity compared with ordinary forms. In this review, we illustrate advances in the most common reproductive management strategies by applying nanotechnology, considering the current challenges of each strategy.

Melatonin-Loaded Nanocarriers: New Horizons for Therapeutic Applications

The use of nanosized particles has emerged to facilitate selective applications in medicine. Drug-delivery systems represent novel opportunities to provide stricter, focused, and fine-tuned therapy, enhancing the therapeutic efficacy of chemical agents at the molecular level while reducing their toxic effects. Melatonin (N-acetyl-5-methoxytriptamine) is a small indoleamine secreted essentially by the pineal gland during darkness, but also produced by most cells in a non-circadian manner from which it is not released into the blood. Although the therapeutic promise of melatonin is indisputable, aspects regarding optimal dosage, biotransformation and metabolism, route and time of administration, and targeted therapy remain to be examined for proper treatment results. Recently, prolonged release of melatonin has shown greater efficacy and safety when combined with a nanostructured formulation. This review summarizes the role of melatonin incorporated into different nanocarriers (e.g., lipid-based vesicles, polymeric vesicles, non-ionic surfactant-based vesicles, charge carriers in graphene, electro spun nanofibers, silica-based carriers, metallic and non-metallic nanocomposites) as drug delivery system platforms or multilevel determinations in various in vivo and in vitro experimental conditions. Melatonin incorporated into nanosized materials exhibits superior effectiveness in multiple diseases and pathological processes than does free melatonin; thus, such information has functional significance for clinical intervention.

Effect of supplementation of medium with Bauhinia forficata recombinant lectins on expression of oxidative stress genes during in vitro maturation of bovine oocytes

The lectin of Bauhinia forficata (nBfL) is a protein able to bind reversibly to N-acetylgalactosamine, performing several functions and one of them is the antiproliferative activity in tumor cells, but its effects have not yet been evaluated in female gametes. The objective of the present study was to determine the additional effect of B. forficata recombinants lectins in the medium of maturation in vitro of bovine oocytes in expression of genes related to oxidative stress pathways. To get the proteins, the gene for this recombinant lectin (rBfL) and its truncated isoform (rtBfL) were cloned and expressed in Escherichia coli (E.coli). The oocytes obtained through follicular puncture were incubated in IVM medium for 24 h containing concentrations of 10 μg/mL, 50 μg/mL and 100 μg/mL of nBfL, rBfL and rtBfL, and a no treated group as a control. In the groups treated with the concentration of 100 μg / mL, the gene expression of genes involved in oxidative stress SOD2, CAT, GPX-1, GSR, NOS2 and apoptosis BAX, CASP3 were evaluated. The rtBfL increased the expression of the SOD2, GSR and NOS2 genes and all the tested lectins increased the expression of the CASP3 gene compared to the control group. These findings indicate that the tested concentrations of the B. forficata recombinants lectins probably influence the expression of oxidative stress genes and increase the expression of the apoptotic gene CASP3 during in vitro maturation of bovine oocytes.

Co-encapsulation of tertinoin and resveratrol by solid lipid nanocarrier (SLN) improves mice in vitro matured oocyte/ morula-compact stage embryo development

As a promising strategy in overcoming drug resistance, the nano drug co-delivery system (NDCDS) can transport two or more drugs into the cell. In this study, we sought to compare the dual and single drug-delivery system, to deliver the optimal dose of Resveratrol (RES) and Tretinoin (TTN) into the in vitro matured oocyte and morula-compact stage embryonic cells. The formation of single (RES/TTN) and dual-drug (RES + TTN)-SLN were confirmed by Uv-vis spectrophotometery, dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) technologies. In two experiments, the oocytes/presumptive zygotes were cultured under various concentrations of the single (RES/TTN) and dual-drug (RES + TTN)-SLN. In vitro toxicity studies, including nuclear staining (Aceto-orcein and Hoechst 33342), H2DCFDA fluorescent staining, chemiluminescence assay, and quantitative reverse transcription-PCR (qRT-PCR) techniques, indicated an excellent oocyte/embryo internalization of RES and TTN. Moreover, when oocytes/embryos were treated with the lowest concentration of RES + TTN-SLN, antioxidants-related genes were upregulated, apoptotic-related genes were downregulated, and intra/extracellular ROS production was reduced. In vitro cytotoxicity studies also demonstrated that single/dual-encapsulation of RES or TTN were safe even at the highest concentration (10 and 5 μM) compared to the control group. To sum it up, both delivery systems of RES and TTN by SLN (dual or single encapsulation) can deliver the optimal dose of RES and TTN into the oocyte/embryo. Where the dual-delivery of RES and TTN even at the lowest concentration (0.25 μM + 0.1 μm) showed a synergistic anti-oxidative effect in oocyte/embryo with a better inhibition of intra/extra-cellular ROS production by an enhanced/controlled intracellular penetration.

Cryoprotective Effect of Tretinoin-Loaded Solid Lipid-Core Nanocapsules During Fresh and Freeze/Thaw Media on NMRI Mouse Sperm Parameters, DNA Damage, and Reactive Oxygen Species Production

Due to the induced oxidative stress that exists in sperm freezing/thawing procedures and handling media, the use of exogenous antioxidant agents seems necessary. Drug delivery by nanocarriers has been designed to overcome the limitations of antioxidants, such as high-dose toxicity and short biological half-life. In this study, we tried to investigate the effects of tretinoin-loaded solid lipid core nanocapsules (TTN-SLN) added to freezing/thawing and handling media (in three experimental groups) on sperm motility (total/progressive), viability, DNA fragmentation, and extracellular reactive oxygen species (ROS) levels. Sperm samples from at least 30 adult male NMRI mice were evaluated in this study. The results of experiments 1 and 2 showed that the addition of 0.5 μM TTN-SLN in freezing and thawing medium significantly increased sperm viability and total/progressive motility and decreased DNA fragmentation and extracellular ROS levels (p < 0.05). Adding 0.25 and 0.5 μM of TTN-SLN to the handling medium (experiment 3), increased sperm parameters and decreased DNA fragmentation and extracellular ROS levels significantly (p < 0.05) compared with the control group. Briefly, our results indicate that SLN can deliver the lowest concentrations of tretinoin in a controlled release mechanism into the intracellular space of sperm. Also, high-dose TTN-SLN is safe during freezing/thawing and handling processes of mouse sperm.

Treatment of in vitro-Matured Bovine Oocytes With Tauroursodeoxycholic Acid Modulates the Oxidative Stress Signaling Pathway

In several species, oocyte and embryo competence are improved by the addition of endoplasmic reticulum (ER) stress inhibitors to in vitro maturation (IVM) medium and/or in vitro culture (IVC) medium. This study aimed to evaluate the effects of three concentrations of tauroursodeoxycholic acid (TUDCA; 50, 200, and 1,000 μM), a chemical chaperone for relieving ER stress, during IVM of bovine cumulus-oocyte complexes (COCs) for 24 h. Treated oocytes were analyzed for nuclear maturation, reactive oxygen species (ROS) production, mitochondrial activity, and abundance of target transcripts. In addition, the number of pronuclei in oocytes was evaluated after 18-20 h of insemination, and the rates of blastocyst and hatched blastocyst formation were evaluated after 7 and 8/9 days of culture, respectively. We further evaluated the transcript abundance of embryonic quality markers. Our findings showed that supplementation of IVM medium with 200 μM of TUDCA decreased ROS production and increased abundance of transcripts related to antioxidant activity in oocytes (CAT, GPX1, and HMOX1) and embryos (GPX1 and PRDX3). Interestingly, high concentration of TUDCA (1,000 μM) was toxic to oocytes, reducing the nuclear maturation rate, decreasing mitochondrial activity, and increasing the abundance of ER stress (HSPA5) and cellular apoptosis (CASP3 and CD40) related transcripts. The results of this study suggest that treatment with 200 μM of TUDCA is associated with a greater resistance to oxidative stress and indirectly with ER stress relief in bovine oocytes.

TRITC-Loaded PLGA Nanoparticles as Drug Delivery Carriers in Mouse Oocytes and Embryos

The structural layers around oocytes make it difficult to deliver drugs aimed at treating infertility. In this study, we sought to identify nanoparticles (NPs) that could easily pass through zona pellucida (ZP), a special layer around oocytes, for use as a drug delivery carrier. Three types of NPs were tested: quantum dot NPs, PE-polyethylene glycol (PEG)-loaded poly(lactic-co-glycolic acid) (PLGA) NPs (PEG/PL), and tetramethylrhodamine-loaded PLGA NPs (TRNPs). When mouse oocytes were treated with NPs, only TRNPs could fully pass through the ZP and cell membrane. To assess the effects of TRNPs on fertility and potential nanotoxicity, we performed mRNA sequencing analysis to confirm their genetic safety. We established a system to successfully internalize TRNPs into oocytes. The genetic stability and normal development of TRNP-treated oocytes and embryos were confirmed. These results imply that TRNPs can be used as a drug delivery carrier applicable to germ cells.

The role of melatonin and Tryptophan-5-hydroxylase-1 in different abiotic stressors in Apis cerana cerana

Tryptophan-5-hydroxylase-1 (T5H-1) is the rate-limiting enzyme in the biosynthesis of serotonin, which is involved in the biosynthesis of melatonin (Mel). Mel, a biological hormone, plays crucial roles in stressors tolerance, such as cold, hot, Ultraviolet (UV) and pesticide tolerance. However, the direct correlation between T5H-1 and Mel and the underlying mechanism in organisms remains elusive. Mel-mediated cold tolerance was studied extensively in plants and somewhat in insects, including bees. The present study isolated the Mel synthesis gene T5H-1 from Apis cerana cerana for the first time. qRT-PCR analysis indicated that AccT5H-1 played vital roles during some adverse conditions, including 4 °C, 8 °C, 10 °C, 45 °C, UV, cyhalothrin, abamectin, paraquat and bifenthrin exposure. Knockdown of AccT5H-1 using RNA interference (RNAi) technology upregulated most antioxidant genes. Additionally, an enzyme activity assay revealed higher contents of Malondialdehyde (MDA) and Hydrogen peroxide (H₂O₂), lower content of Vitamin C (VC), and higher activities of Glutathione S-transferase (GST), Superoxide dismutase (SOD), Catalase (CAT) and Peroxidase (POD) in the AccT5H-1 silenced group than the control group. These results suggest that AccT5H-1 is involved in the response to different oxidative stressors in A. cerana cerana. The survival rate of A. cerana cerana exposed to low temperature treatment revealed that the optimal concentration of Mel in the diet was 10 µg/mL. We also found that the antioxidant enzyme (GST, SOD, POD and CAT) concentrations at 10 µg/mL Mel increased to different degrees, and the content of oxidizing substances (MDA and H₂O₂) decreased, the content of VC increased, and the content of substances that promote cold resistance (glycerol and glycogen) increased. Mel increased the resistance of A. cerana cerana exposed to low temperatures. The expression of AccT5H-1 decreased after the feeding of exogenous Mel to bees. These results provide a reference for other insect studies on Mel and T5H-1.

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.

Melatonin enhances in vitro developmental competence of cumulus-oocyte complexes collected by ovum pick-up in prepubertal and adult dairy cattle

Bovine oocytes from prepubertal donors have been used for in vitro embryo production to decrease the generation interval. However, reduced cumulus-oocyte competence, mainly attributed to increased apoptosis, has been observed in oocytes/embryos collected from prepubertal donors. Here, we investigated the effects of the potent antioxidative molecule melatonin on cumulus-oocyte competence and embryo development in prepubertal and adult dairy cattle in vitro. A total of fifteen Holstein Friesian calves, six to ten months old (7.6 ± 1.34 months of age). And fifteen adult cows with one to four calvings (2.3 ± 0.96 calvings) were enrolled as ovum pick up (OPU) donors in this study. Cumulus-oocyte complexes (COCs) were cultured either in the presence or absence of melatonin (0.01 nM). The proportion of cleavage stages, blastocysts, and advanced blastocysts was determined. Embryo quality was assessed via differential staining to determine the total embryonic cells and allocation to the inner cell mass (ICM) and trophectoderm (TE) cells. Melatonin treatment yielded a greater percentage of blastocysts compared to the control group, i.e. oocytes from both adult cows (P = 0.0485; 24.8 ± 3.5% vs. 16.0 ± 3.4%, respectively), and from prepubertal donors (P = 0.0007; Melatonin 23.1 ± 5.1% vs. Control: 11.1 ± 3.5%). Adult cows had significantly (P = 0.0370) greater advanced blastocyst rates than those found in the prepubertal group (13.9%± vs. 7.0±%, respectively). Additionally, the number of ICM, total cells, and the ratios ICM: Total, ICM: TE, respectively, were greater (P < 0.05) after melatonin treatment compared with the control group (39.1 ± 2.8, 98.6 ± 5.7, 0.4 ± 0.01, and 0.7 ± 0.04 vs. 27.3 ± 2.9, 81.2 ± 5.8, 0.34 ± 0.01, and 0.52 ± 0.04, respectively). Blastocysts derived from adult cows had a greater number of TE (P = 0.01) and total embryonic cells (P = 0.0095) compared to the prepubertal donor group (63.5 ± 3.2 and 101.05 ± 4.8 vs. 48.9 ± 4.3 and 78.8 ± 6.5, respectively). Nevertheless, embryonic cell counting in embryos derived from prepubertal COCs equated to that observed from adult donors after melatonin exposure. In conclusion, these results indicate that the presence of melatonin during in vitro maturation improves cumulus-oocyte competence, embryo development, and quality by increasing the allocation of embryonic cells to the ICM compartment and the total number of embryonic cells in both adult and prepubertal bovine donors.

Blastocoel fluid removal and melatonin supplementation in the culture medium improve the viability of vitrified bovine embryos

In this study, we investigated the effects of melatonin supplementation in the culture medium and blastocoel fluid removal (BFR) before vitrification on the quality and viability of in vitro-derived bovine embryos. After fertilization, presumptive zygotes were assigned to one of the following treatments: control, in vitro standard culture (IVC) medium; IVC + M10^-9, IVC medium supplemented 10^-9 M melatonin; or IVC + M10^-9 BFR, IVC medium supplemented with 10^-9 M melatonin plus BFR on day 7 (D7) of culture. D7 blastocysts were vitrified by the Cryotop method and, after 5 mo of storage, were warmed and incubated for an additional 72 h. The re-expansion rate was evaluated after 2 and 24 h, and the hatching rate was evaluated after 24, 48, and 72 h. At 72 h, the total number of cells (TNC); number of apoptotic cells (NAC); and expression of genes related to oxidative stress (HSPA5), cell metabolism (SLC2A3), cell repair (MSH6), placentation (KRT8 and PLAC8), and implantation (FOSL1) were assessed in the blastocysts. Less than 30% of the control blastocysts re-expanded until 2 h, whereas more than 85% of the IVC + M10^-9 and IVC + M10^-9 BFR blastocysts re-expanded (P < 0.05). The hatching rate of IVC + M10^-9 BFR blastocysts increased at all time points (P < 0.05), reaching 66.8% at 72 h of incubation. The TNC was similar among treatments (P > 0.05), regardless of vitrification/warming and re-cultivation. The NAC:TNC was smaller for melatonin-treated blastocysts (P < 0.05). BFR increased HSPA5 (P = 0.0118) expression and did not affect SLC2A3, MSH6, KRT8, and FOSL1 expression (P > 0.05). In conclusion, melatonin (10^-9 M) supplementation in the culture medium and BFR on D7 of culture increased the hatching rate 24, 48, and 72 h after warming of the vitrified embryos, indicating an improvement in cryotolerance.

Effects of melatonin on the in vitro growth of early antral follicles and maturation of ovine oocytes

This study aimed to evaluate the effect of melatonin on the in vitro culture and maturation of isolated sheep early antral follicles. Isolated early antral follicles were cultured for 12 d in α-minimum essential medium (MEM⁺) alone (control) or α-MEM⁺ added with fixed different concentrations (100, 500, or 1,000 pg/mL) or a sequential concentration of melatonin (MelSeq; day 6 = 100; day 12 = 500 pg/mL). The percentage of morphologically normal follicles was higher (P < 0.05) in 500 pg/mL melatonin than the other treatments at 6 d. Mel 500 also showed a higher rate of fully grown oocytes (P < 0.05) than other treatments. After in vitro culture, reactive oxygen species (ROS) levels in oocytes were similar between Mel 500 and MelSeq, with both being lower (P < 0.05) than other treatments. Oocytes cultured in both Mel 500 and Mel 1000 showed glutathione peroxidase levels similar (P > 0.05) to the control group and higher (P < 0.05) than other treatments. Mitochondrial activity was similar (P > 0.05) among control, Mel 500, and Mel 1000 treatments. Mel 500 treatment presented a higher percentage of germinal vesicle breakdown oocytes than the control group and similar percentages to the other treatments. Follicles cultured in melatonin followed by oocyte maturation with the addition of 500 pg/mL melatonin in maturation medium showed increased (P < 0.05) levels of mitochondrial activity compared to α-MEM⁺ alone. In conclusion, the concentration of 500 pg/mL of melatonin promotes development and decreases ROS levels of ovine oocytes from in vitro grown early antral follicles. Moreover, melatonin increases mitochondrial activity and promotes the acquisition of meiotic competence of these oocytes.

Effect of Melatonin on the In Vitro Maturation of Porcine Oocytes, Development of Parthenogenetically Activated Embryos, and Expression of Genes Related to the Oocyte Developmental Capability

Simple Summary

Exogenous melatonin has beneficial effects on improving cumulus oophorus expansion; mitochondrial distribution; intracellular level of glutathione; and first polar body extrusion rate of porcine oocytes derived from in vitro maturation. Moreover; melatonin supplementation increases relative abundances of BMP15 and CAT mRNA; and decreases intracellular levels of reactive oxygen species; and expression values of P53 and BAX genes; which are related to in vitro development of porcine oocytes.

Abstract

Melatonin treatment can improve quality and in vitro development of porcine oocytes, but the mechanism of improving quality and developmental competence is not fully understood. In this study, porcine cumulus–oocyte complexes were cultured in TCM199 medium with non-treated (control), 10⁻⁵ M luzindole (melatonin receptor antagonist), 10⁻⁵ M melatonin, and melatonin + luzindole during in vitro maturation, and parthenogenetically activated (PA) embryos were treated with nothing (control), or 10⁻⁵ M melatonin. Cumulus oophorus expansion, oocyte survival rate, first polar body extrusion rate, mitochondrial distribution, and intracellular levels of reactive oxygen species (ROS) and glutathione of oocytes, and cleavage rate and blastocyst rate of the PA embryos were assessed. In addition, expression of growth differentiation factor 9 (GDF9), tumor protein p53 (P53), BCL2 associated X protein (BAX), catalase (CAT), and bone morphogenetic protein 15 (BMP15) were analyzed by real-time quantitative PCR. The results revealed that melatonin treatment not only improved the first polar body extrusion rate and cumulus expansion of oocytes via melatonin receptors, but also enhanced the rates of cleavage and blastocyst formation of PA embryos. Additionally, melatonin treatment significantly increased intraooplasmic level of glutathione independently of melatonin receptors. Furthermore, melatonin supplementation not only significantly enhanced mitochondrial distribution and relative abundances of BMP15 and CAT mRNA, but also decreased intracellular level of ROS and relative abundances of P53 and BAX mRNA of the oocytes. In conclusion, melatonin enhanced the quality and in vitro development of porcine oocytes, which may be related to antioxidant and anti-apoptotic mechanisms.

Enhanced delivery of melatonin loaded nanostructured lipid carriers during in vitro fertilization: NLC formulation, optimization and IVF efficacy

In this study, the potential of melatonin hormone loaded in nanostructured lipid carriers (Mel-NLCs) in the in vitro fertilization (IVF) environment is investigated by measuring the appropriate IVF parameters on the oocytes of mice.

Melatonin improves development, mitochondrial function and promotes the meiotic resumption of sheep oocytes from in vitro grown secondary follicles

The aim of this study was to evaluate follicular survival and development of ovine isolated secondary follicles cultured in medium containing fixed or sequential concentrations of melatonin and further oocyte maturation. Isolated secondary follicles were cultured for 18 days in α-MEM⁺ alone (control) or with different concentrations of melatonin (100, 500 or 1000 pg/mL) or sequential concentrations of melatonin (Mel Seq: Day 6 = 100; Day 12 = 500; Day 18 = 1000 pg/mL). The percentages of morphologically normal follicles and antral cavity formation increased significantly in 1000 pg/mL melatonin compared to the other treatments. After 18 days, 1000 pg/mL melatonin (Mel 100) showed a greater (P < 0.05) follicular diameter than α-MEM⁺, 100 and 500 pg/mL melatonin. In addition, the concentration of 500 pg/mL melatonin showed a higher (P < 0.05) percentage of fully grown oocytes than α-MEM⁺, Mel 100 and Mel Seq treatments. After oocyte maturation, the levels of ROS were lower (P < 0.05) in 1000 pg/mL melatonin (Mel 1000) than in other treatments. Both Mel 1000 and Mel Seq treatments showed significantly higher levels of mitochondrial activity than other treatments. There were no significant differences between 500 and 1000 pg/mL melatonin regarding meiotic stages. In conclusion, the concentration of 1000 pg/mL melatonin maintains survival, promotes follicular development and increases the levels of active mitochondria after in vitro culture of sheep secondary follicles. Moreover, this concentration promotes the meiotic competence of oocytes and decreases the production of ROS during oocyte maturation.

Applications of omics and nanotechnology to improve pig embryo production in vitro

An appropriate environment to optimize porcine preimplantation embryo production in vitro is required as genetically modified pigs have become indispensable for biomedical research and agriculture. To provide suitable culture conditions, omics technologies have been applied to elucidate which metabolic substrates and pathways are involved during early developmental processes. Metabolomic profiling and transcriptional analysis comparing in vivo- and in vitro-derived embryos have demonstrated the important role of amino acids during preimplantation development. Transcriptional profiling studies have been helpful in assessing epigenetic reprogramming agents to allow for the correction of gene expression during the cloning process. Along with this, nanotechnology, which is a highly promising field, has allowed for the use of engineered nanoplatforms in reproductive biology. A growing number of studies have explored the use of nanoengineered materials for sorting, labeling, and targeting purposes; which demonstrates their potential to become one of the solutions for precise delivery of molecules into gametes and embryos. Considering the contributions of omics and the recent progress in nanoscience, in this review, we focused on their emerging applications for current in vitro pig embryo production systems to optimize the generation of genetically modified animals.

Toxicological evaluation of 3-(4-Chlorophenylselanyl)-1-methyl-1H-indole through the bovine oocyte in vitro maturation model

The development of new bioactive molecules based on the molecular hybridization has been widely explored. In line with this, reliable tests should be employed to give information about the toxicology of these new molecules. In this sense, the use of in vitro tests is a valuable tool, especially the in vitro maturation of oocytes (IVM), which is an efficient resource to discover the potential toxicity of synthetic molecules. Thus, the aim of the present study was to evaluate the toxicological effects of the selenium-containing indolyl compound 3-(4-Chlorophenylselanyl)-1-methyl-1H-indole (CMI), on different quality parameters of bovine oocytes through the IVM. Different concentrations of the CMI compound (0, 25, 50, 100, 200 μM) were supplemented during the in vitro maturation process. After, the oocyte maturation rate, glutathione (GSH) levels, reactive oxygen species (ROS) levels, membrane, and mitochondrial integrity were evaluated. The results showed that the lowest concentration of CMI induced the highest GSH production (P < 0.05), an important marker of cytoplasmic quality and maturation. All treatments increased ROS production in relation to non-supplementation (P < 0.05). In addition, oocyte maturation was reduced only with the highest concentration of CMI (P < 0.05). Supplementation with CMI did not impact mitochondrial activity, integrity and cell membrane. To our knowledge, this is the first study that evaluates CMI on the oocyte in vitro maturation process. Importantly, our results did not find any toxic effect of CMI on bovine oocytes. CMI was efficient for cytoplasmic maturation by promoting an increase in the intracellular levels of glutathione.

Melatonin attenuates palmitic acid-induced mouse granulosa cells apoptosis via endoplasmic reticulum stress

Background

Palmitic acid (PA), the main component of dietary saturated fat, causes apoptosis in many cell types, including mouse granulosa cell. Melatonin, an important endogenous hormone, has beneficial effects on female reproductive processes. Since elevated PA levels are present in follicular fluid (FF) of patients with infertility and are shown to be toxic for granulosa cells, we investigated the molecular mechanisms of PA toxicity in mouse granulosa cells and explored the effects of melatonin on PA-induced apoptosis.

Methods

Granulosa cells from immature female mice were cultured for 24 h in medium containing PA and/or melatonin. Then, the effects of PA alone or combined with melatonin on viability, apoptosis and endoplasmic reticulum (ER) stress in granulosa cells were detected by methyl thiazolyl tetrazolium (MTT) assay, flow cytometry assay and western blot. After 48 h of PA and/or melatonin treatment, the concentrations of estradiol (E2) and progesterone (P4) in the culture supernatants were measured with ELISA kits.

Results

In this study, we explored the effects of melatonin on cell viability and apoptosis in PA-treated mouse granulosa cells and uncovered the signaling pathways involved in these processes. Our results showed that 200-800 μM PA treatment reduces cell viability, induces cell apoptosis, enhances the expression of apoptosis-related genes (Caspase 3 and B-cell lymphoma-2 (BCL-2) associated X protein (BAX)), and activates the expression of ER stress marker genes (glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP)). Melatonin treatment (1-10 μM) suppresses 400 μM PA-induced cell viability decrease, cell apoptosis, Caspase 3 activation, and BAX, CHOP, and GRP78 expression. In addition, we found that 10 μM melatonin successfully attenuated the 400 μM PA-induced estrogen (E2) and progesterone (P4) decreases.

Conclusions

This study suggests that PA triggers cell apoptosis via ER stress and that melatonin protects cells against apoptosis by inhibiting ER stress in mouse granulosa cells.

Electronic supplementary material

The online version of this article (10.1186/s13048-019-0519-z) contains supplementary material, which is available to authorized users.

Beneficial effects of melatonin on in vitro embryo production from juvenile goat oocytes

Melatonin is a universal antioxidant that improves in vitro embryo production in several species. The aims of this study were to determine the melatonin concentration in the ovarian follicular fluid (FF) of juvenile goats and the effect of melatonin during in vitro maturation (IVM) on embryo development. The FF melatonin concentration was 0.57--1.07×10-9 M, increasing with follicular diameter. Oocytes were matured, fertilised and cultured under conventional conditions. Blastocyst development, embryo quality and levels of reactive oxygen species (ROS) and reduced glutathione were assessed. In Experiment 1 different melatonin concentrations (10-3, 10-7, 10-9, 10-11 M) were added to the IVM medium, which contained cysteamine as antioxidant, and no differences were observed. In Experiment 2, melatonin (10-7 M) was tested in the presence or absence of cysteamine (experimental groups: melatonin, cysteamine, melatonin+cysteamine, non-antioxidant). The melatonin group presented a higher blastocyst rate than the non-antioxidant group (28.9 vs 11.7%; P<0.01) and a higher total cell number than the cysteamine group (225.1 vs 129.0; P<0.05). Oocytes from the melatonin and cysteamine groups had lower ROS levels than those from the non-antioxidant group. This study shows that melatonin is an interesting tool for improving oocyte competence in juvenile goats as it increases embryo production and quality.

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.

Protective effects of melatonin on the in vitro developmental competence of bovine oocytes

The present study investigated the effects of melatonin on bovine oocyte maturation and subsequent embryonic development in vitro. Results showed that the nuclear and cytoplasmic maturation, characterized by first polar body extrusion, normal distribution of cortical granules and mitochondria, as well as increased mitochondrial membrane potential, were significantly improved in 10^-9  mol/L melatonin-treated oocytes. Melatonin supplementation reduced intracellular reactive oxygen species level and enhanced glutathione production. Meanwhile, the presence of melatonin (10^-9  mol/L) during oocyte maturation resulted in a decreased early apoptotic rate in oocytes. After in vitro fertilization, oocytes receiving melatonin supplementation exhibited a significantly higher blastocyst formation rate and yielded a markedly lower number of apoptotic cells. Mechanistic explorations showed that addition of 10^-9  mol/L melatonin to in vitro maturation media significantly attenuated the transcript level of caspase-3, while the expressions of BCL-2, XIAP, CAT and HSP70 were significantly reinforced in the resultant embryos. Taken together, melatonin ameliorates bovine oocyte maturation potential, and the beneficial effects can affect subsequent embryonic development. The protective role of melatonin may be due to its anti-apoptotic and anti-oxidative activities.

Melatonin and the electron transport chain

Melatonin protects the electron transport chain (ETC) in multiple ways. It reduces levels of ·NO by downregulating inducible and inhibiting neuronal nitric oxide synthases (iNOS, nNOS), thereby preventing excessive levels of peroxynitrite. Both ·NO and peroxynitrite-derived free radicals, such as ·NO2, hydroxyl (·OH) and carbonate radicals (CO3·-) cause blockades or bottlenecks in the ETC, by ·NO binding to irons, protein nitrosation, nitration and oxidation, changes that lead to electron overflow or even backflow and, thus, increased formation of superoxide anions (O2·-). Melatonin improves the intramitochondrial antioxidative defense by enhancing reduced glutathione levels and inducing glutathione peroxidase and Mn-superoxide dismutase (Mn-SOD) in the matrix and Cu,Zn-SOD in the intermembrane space. An additional action concerns the inhibition of cardiolipin peroxidation. This oxidative change in the membrane does not only initiate apoptosis or mitophagy, as usually considered, but also seems to occur at low rate, e.g., in aging, and impairs the structural integrity of Complexes III and IV. Moreover, elevated levels of melatonin inhibit the opening of the mitochondrial permeability transition pore and shorten its duration. Additionally, high-affinity binding sites in mitochondria have been described. The assumption of direct binding to the amphipathic ramp of Complex I would require further substantiation. The mitochondrial presence of the melatonin receptor MT1 offers the possibility that melatonin acts via an inhibitory G protein, soluble adenylyl cyclase, decreased cAMP and lowered protein kinase A activity, a signaling pathway shown to reduce Complex I activity in the case of a mitochondrial cannabinoid receptor.

Melatonin Scavenger Properties against Oxidative and Nitrosative Stress: Impact on Gamete Handling and In Vitro Embryo Production in Humans and Other Mammals

Oxidative and nitrosative stress are common problems when handling gametes in vitro. In vitro development in mammalian embryos is highly affected by culture conditions, especially by reactive oxygen species (ROS) and reactive nitrogen species (RNS), because their absence or overproduction causes embryo arrest and changes in gene expression. Melatonin in gamete co-incubation during in vitro fertilization (IVF) has deleterious or positive effects, depending on the concentration used in the culture medium, demonstrating the delicate balance between antioxidant and pro-oxidant activity. Further research is needed to better understand the possible impact of melatonin on the different IVP steps in humans and other mammals, especially in seasonal breeds where this neuro-hormone system highly regulates its reproduction physiology.

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.