Seminal extracellular vesicles subsets modulate gene expression in cumulus cells of porcine in vitro matured oocytes

Swine in vitro embryo production: Potential, challenges, and advances

Pig production, a vital sector of the meat industry, faces demands for improved quality, efficiency, and sustainability. Advancements in breeding, disease control, and artificial insemination have enhanced production, while biotechnologies such as in vitro embryo production (IVP) and genetic engineering offer further progress. In vitro embryo production could facilitate the global exchange of valuable genetic material, accelerate breeding programs, and improve productivity, and it is essential for generating genetically modified (GM) pigs. These GM pigs have two main applications: first, they allow for targeted modifications aimed at improving production traits relevant to pig production in agriculture, such as meat quality and disease resistance. Second, they serve as valuable biomedical models for human disease research, regenerative medicine, and organ transplantation. Yet, despite notable advancements in recent decades, the efficiency of the current IVP systems for porcine embryos remains a challenge. Compared to the in vivo environment, suboptimal culture conditions lead to issues such as elevated polyspermy, poor embryo development, and the production of low-quality blastocysts. This review provides an overview of the key steps and recent advancements in porcine IVP technology. We will emphasize the promising utilization of oocytes from live females of high genetic value through ovum pick-up and the incorporation of extracellular vesicles and cytokines into IVP media. These innovative strategies hold immense potential to significantly enhance embryo development and overall success rates in porcine IVP, and could open the door for significant progress in both agriculture and biomedicine applications.

Integrating metabolomics into reproduction: Sperm metabolism and fertility enhancement in pigs

The last decades of research have revealed that many other factors besides gamete genomes are able to determine the reproductive outcomes. Indeed, paternal factors have been observed to be capable of modulating multiple crucial features of the reproductive process, such as sperm physiology, the maternal environment and, even, the offspring health. These recent advances have been encompassed with the emergence of OMICS technologies, as they comprehensively characterise the molecular composition of biological systems. The present narrative review aimed to take a closer look at the potential of these technologies in the field of reproductive biology. This literature revision shows that most studies up to date have followed a non-targeted approach to screen mammalian seminal plasma (SP) and sperm metabolite composition through different metabolome platforms. These studies have proposed metabolites of multiple natures as potential in vivo fertility biomarkers. Yet, targeted approaches can be used to answer specific biological question, and their power is exemplified herein. For instance, metabolomic studies have uncovered not only that glycolysis is the main ATP energy source of pig sperm, but also that sperm metabolism can trigger DNA damage, hence compromise embryo development. In conclusion, this review shows the potential of both non-targeted and targeted metabolomics for the discovery of cell pathways that govern the reproductive process. Understanding these systems could help make progress in different areas, including livestock efficient breeding, the improvement of artificial reproductive technologies, and the development of biomarkers for infertility detection.

Sperm functionality is differentially regulated by porcine oviductal extracellular vesicles from the distinct phases of the estrous cycle

Context Extracellular vesicles (EVs) derived from the oviductal fluid (oEVs) play a critical role in various reproductive processes, including sperm capacitation, fertilisation, and early embryo development. Aims To characterise porcine oEVs (poEVs) from different stages of the estrous cycle (late follicular, LF; early luteal, EL; mid luteal, ML; late luteal, LL) and investigate their impact on sperm functionality. Methods poEVs were isolated, characterised, and labelled to assess their binding to boar spermatozoa. The effects of poEVs on sperm motility, viability, acrosomal status, protein kinase A phosphorylation (pPKAs), tyrosine phosphorylation (Tyr-P), and in in vitro fertility were analysed. Key results poEVs were observed as round or cup-shaped membrane-surrounded vesicles. Statistical analysis showed that poEVs did not significantly differ in size, quantity, or protein concentration among phases of the estrous cycle. However, LF poEVs demonstrated a higher affinity for binding to sperm. Treatment with EL, ML, and LL poEVs resulted in a decrease in sperm progressive motility and total motility. Moreover, pPKA levels were reduced in presence of LF, EL, and ML poEVs, while Tyr-P levels did not differ between groups. LF poEVs also reduced sperm penetration rate and the number of spermatozoa per penetrated oocyte (P Conclusions poEVs from different stages of the estrous cycle play a modulatory role in sperm functionality by interacting with spermatozoa, affecting motility and capacitation, and participating in sperm-oocyte interaction. Implications The differential effects of LF and LL poEVs suggest the potential use of poEVs as additives in IVF systems to regulate sperm-oocyte interaction.

Seminal extracellular vesicles alter porcine in vitro fertilization outcome by modulating sperm metabolism

Porcine seminal plasma (SP) is loaded with a heterogeneous population of extracellular vesicles (sEVs) that modulate several reproductive-related processes. This study investigated the effect of two sEV subsets, small (S-sEVs) and large (L-sEVs), on porcine in vitro fertilization (IVF). The sEVs were isolated from nine SP pools (five ejaculates/pool) using a size-exclusion chromatography-based procedure and characterized for quantity (total protein), morphology (cryogenic electron microscopy), size distribution (dynamic light scattering), purity and EV-protein markers (flow cytometry; albumin, CD81, HSP90β). The characterization confirmed the existence of two subsets of high purity (low albumin content) sEVs that differed in size (S- and L-sEVs). In vitro fertilization was performed with in vitro matured oocytes and frozen-thawed spermatozoa and the IVF medium was supplemented during gamete coincubation (1 h at 38.5 °C, 5 % CO2 in a humidified atmosphere) with three different concentrations of each sEV subset: 0 (control, without sEVs), 0.1, and 0.2 mg/mL. The first experiment showed that sEVs, regardless of subset and concentration, decreased penetration rates and total IVF efficiency (P < 0.0001). In a subsequent experiment, it was shown that sEVs, regardless of subset and concentration, impaired the ability of spermatozoa to bind to the zona pellucida of oocytes (P < 0.0001). The following experiment showed that sEVs, regardless of the subset, bound to frozen-thawed sperm but not to in vitro matured oocytes, indicating that sEVs would affect sperm functionality but not oocyte functionality. The lack of effect on oocytes was confirmed by incubating sEVs with oocytes prior to IVF, achieving sperm-zona pellucida binding results similar to those of control. In the last experiment, conducted under IVF conditions, sperm functionality was analyzed in terms of tyrosine phosphorylation, acrosome integrity and metabolism. The sEVs, regardless of the subset, did not affect sperm tyrosine phosphorylation or acrosome integrity, but did influence sperm metabolism by decreasing sperm ATP production under capacitating conditions. In conclusion, this study demonstrated that the presence of sEVs on IVF medium impairs IVF outcomes, most likely by altering sperm metabolism.

Follicular Fluid-Derived Extracellular Vesicles Influence on In Vitro Maturation of Equine Oocyte: Impact on Cumulus Cell Viability, Expansion and Transcriptome

Cumulus cell (CC) expansion is pivotal for oocyte maturation, during which CCs release factors that initiate paracrine signaling within the follicular fluid (FF). The FF is abundant in extracellular vesicles (EVs) that facilitate intercellular communication. Although bovine and murine EVs can control cumulus expansion, these effects have not been observed in equines. This study aimed to assess the impact of FF-derived EVs (ffEVs) on equine CC expansion, viability, and transcriptome. Cumulus-oocyte complexes (COCs) that underwent in vitro maturation (IVM) in the presence (200 µg protein/mL) or absence (control) of ffEVs were assessed for cumulus expansion and viability. CCs were isolated after 12 h of IVM, followed by RNA extraction, cDNA library generation, and subsequent transcriptome analysis using next-generation sequencing. Confocal microscopy images illustrated the internalization of labeled ffEVs by CCs. Supplementation with ffEVs significantly enhanced cumulus expansion in both compacted (Cp, p < 0.0001) and expanded (Ex, p < 0.05) COCs, while viability increased in Cp groups (p < 0.01), but decreased in Ex groups (p < 0.05), compared to the controls. Although transcriptome analysis revealed a subtle effect on CC RNA profiles, differentially expressed genes encompassed processes (e.g., MAPK and Wnt signaling) potentially crucial for cumulus properties and, consequently, oocyte maturation.

Immunophenotype profile by flow cytometry reveals different subtypes of extracellular vesicles in porcine seminal plasma

BACKGROUND

Porcine seminal plasma (SP) is endowed with a heterogeneous population of extracellular vesicles (sEVs). This study evaluated the immunophenotypic profile by high-sensitivity flow cytometry of eight sEV subpopulations isolated according to their size (small [S-sEVs] and large [L-sEVs]) from four different SP sources, namely three ejaculate fractions (the first 10 mL of the sperm rich fraction [SRF-P1], the remaining SRF [SRF-P2], and the post-SRF [PSRF]) and entire ejaculate (EE).

METHODS

Seminal EVs were isolated using a size exclusion chromatography-based protocol from six SP pools (five ejaculates/pool) of each SP source and characterized using complementary approaches including total protein (BCA™assay), particle size distribution (dynamic light scattering), morphology (transmission electron microscopy), and purity (albumin by Western blot). Expression of CD9, CD63, CD81, CD44 and HSP90β was analyzed in all sEV subpopulations by high-sensitivity flow cytometry according to MIFlowCyt-EV guidelines, including an accurate calibration, controls, and discrimination by CFSE-labelling.

RESULTS

Each sEV subpopulation exhibited a specific immunophenotypic profile. The percentage of sEVs positive for CD9, CD63, CD81 and HSP90β differed between S- and L-sEVs (P < 0.0001). Specifically, the percentage of sEVs positive for CD9 and CD63 was higher and that for CD81 was lower in S- than L-sEVs in the four SP sources. However, the percentage of HSP90β-positive sEVs was lower in S-sEVs than L-sEVs in the SRF-P1 and EE samples. The percentage of sEVs positive for CD9, CD63, and CD44 also differed among the four SP sources (P < 0.0001), being highest in PSRF samples. Notably, virtually all sEV subpopulations expressed CD44 (range: 88.04-98.50%).

CONCLUSIONS

This study demonstrated the utility of high-sensitivity flow cytometry for sEV immunophenotyping, allowing the identification of distinct sEV subpopulations that may have different cellular origin, cargo, functions, and target cells.

miR-302d Targeting of CDKN1A Regulates DNA Damage and Steroid Hormone Secretion in Bovine Cumulus Cells

(1) Background: DNA damage in cumulus cells hinders oocyte maturation and affects steroid hormone secretion. It is crucial to identify the key factors that regulate cellular DNA damage and steroid hormone secretion. (2) Methods: Treatment of bovine cumulus cells with bleomycin to induce DNA damage. The effects of DNA damage on cell biology were determined by detecting changes in DNA damage degree, cell cycle, viability, apoptosis, and steroid hormones. It was verified that mir-302d targeted regulation of CDKN1A expression, and then affected DNA damage and steroid hormone secretion in cumulus cells. (3) Results: Bleomycin induced increased DNA damage, decreased G1-phase cells, increased S-phase cells, inhibited proliferation, promoted apoptosis, affected E2 and P4 secretion, increased CDKN1A expression, and decreased miR-302d expression. Knockdown of CDKN1A reduced DNA damage, increased G1-phase cells, decreased G2-phase cells, promoted proliferation, inhibited apoptosis, increased E2 and P4 secretion, and increased the expression of BRCA1, MRE11, ATM, CDK1, CDK2, CCNE2, STAR, CYP11A1, and HSD3B1. The expression of RAD51, CCND1, p53, and FAS was decreased. Overexpression of CDKN1A resulted in the opposite results. miR-302d targets CDKN1A expression to regulate DNA damage and then affects the cell cycle, proliferation, apoptosis, steroid hormone secretion, and the expression of related genes. (4) Conclusions: miR-302d and CDKN1A were candidate molecular markers for the diagnosis of DNA damage in bovine cumulus cells.

Granulosa cell-derived extracellular vesicles mitigate the detrimental impact of thermal stress on bovine oocytes and embryos

Climate change-induced global warming results in rises in body temperatures above normal physiological levels (hyperthermia) with negative impacts on reproductive function in dairy and beef animals. Extracellular vesicles (EVs), commonly described as nano-sized, lipid-enclosed complexes, harnessed with a plethora of bioactive cargoes (RNAs, proteins, and lipids), are crucial to regulating processes like folliculogenesis and the initiation of different signaling pathways. The beneficial role of follicular fluid-derived EVs in inducing thermotolerance to oocytes during in vitro maturation (IVM) has been evidenced. Here we aimed to determine the capacity of in vitro cultured granulosa cell-derived EVs (GC-EVs) to modulate bovine oocytes’ thermotolerance to heat stress (HS) during IVM. Moreover, this study tested the hypothesis that EVs released from thermally stressed GCs (S-EVs) shuttle protective messages to provide protection against subsequent HS in bovine oocytes. For this, sub-populations of GC-EVs were generated from GCs subjected to 38.5°C (N-EVs) or 42°C (S-EVs) and supplemented to cumulus-oocyte complexes (COCs) matured in vitro at the normal physiological body temperature of the cow (38.5°C) or HS (41°C) conditions. Results indicate that S-EVs improve the survival of oocytes by reducing ROS accumulation, improving mitochondrial function, and suppressing the expression of stress-associated genes thereby reducing the severity of HS on oocytes. Moreover, our findings indicate a carryover impact from the addition of GC-EVs during oocyte maturation in the development to the blastocyst stage with enhanced viability.

Messenger roles of extracellular vesicles during fertilization of gametes, development and implantation: Recent advances

Extracellular vesicles (EVs) have become a research hotspot in recent years because they act as messengers between cells in the physiological and pathological processes of the human body. It can be produced by the follicle, prostate, embryo, uterus, and oviduct in the reproductive field and exists in the extracellular environment as follicular fluid, semen, uterine cavity fluid, and oviduct fluid. Because extracellular vesicles are more stable at transmitting information, it allows all cells involved in the physiological processes of embryo formation, development, and implantation to communicate with one another. Extracellular vesicles carried miRNAs and proteins as mail, and when the messenger delivers the mail to the recipient cell, the recipient cell undergoes a series of changes. Current research begins with intercepting and decoding the information carried by extracellular vesicles. This information may help us gain a better understanding of the secrets of reproduction, as well as assist reproductive technology as an emerging marker and treatment.