Extracellular Vesicles, the Road toward the Improvement of ART Outcomes

Oviductal extracellular vesicles miRNA cargo varies in response to embryos and their quality

BACKGROUND

Increasing evidence points to an active role of oviductal extracellular vesicles (oEVs) in the early embryo-maternal dialogue. However, it remains unclear whether oEVs contribute to the recognition of the presence of embryos and their quality in the oviduct. Hence, we examined whether the molecular cargo of oEVs secreted by bovine oviduct epithelial cells (BOEC) differs depending on the presence of good (≥ 8 cells, G) or poor (< 8 cells, P) quality embryos. In addition, differences in RNA profiles between G and P embryos were analyzed in attempt to distinguish oEVs and embryonic EVs cargos.

METHODS

For this purpose, primary BOEC were co-cultured with in vitro produced embryos (IVP) 53 h post fertilization as follows: BOEC with G embryos (BGE); BOEC with P embryos (BPE); G embryos alone (GE); P embryos alone (PE); BOEC alone (B) and medium control (M). After 24 h of co-culture, conditioned media were collected from all groups and EVs were isolated and characterized. MicroRNA profiling of EVs and embryos was performed by small RNA-sequencing.

RESULTS

In EVs, 84 miRNAs were identified, with 8 differentially abundant (DA) miRNAs for BGE vs. B and 4 for BPE vs. B (P-value < 0.01). In embryos, 187 miRNAs were identified, with 12 DA miRNAs for BGE vs. BPE, 3 for G vs. P, 8 for BGE vs. GE, and 11 for BPE vs. PE (P-value < 0.01).

CONCLUSIONS

These results indicated that oEVs are involved in the oviductal-embryo recognition and pointed to specific miRNAs with signaling and supporting roles during early embryo development.

Extracellular Vesicles in Domestic Animals: Cellular Communication in Health and Disease

Apoptotic and healthy cells of domestic animals release membrane-enclosed particles from their plasma membrane. These special structures, called extracellular vesicles, play an important role in intercellular communication. In the past, it was believed that their function was mainly to dispose unwanted cell contents and to help maintain cell homeostasis. However, we now know that they have important roles in health and disease and have diagnostic value as well as great potential for therapy in veterinary medicine. Extracellular vesicles facilitate cellular exchanges by delivering functional cargo molecules to nearby or distant tissues. They are produced by various cell types and are found in all body fluids. Their cargo reflects the state of the releasing parent cell, and despite their small size, this cargo is extraordinarily complex. Numerous different types of molecules contained in vesicles make them an extremely promising tool in the field of regenerative veterinary medicine. To further increase research interest and discover their full potential, some of the basic biological mechanisms behind their function need to be better understood. Only then will we be able to maximize the clinical relevance for targeted diagnostic and therapeutic purposes in various domestic animal species.

The embryo non-invasive pre-implantation diagnosis era: how far are we?

Advancements in assisted reproduction (AR) methodologies have allowed significant improvements in live birth rates of women who otherwise would not be able to conceive. One of the tools that allowed this improvement is the possibility of embryo selection based on genetic status, performed via preimplantation genetic testing (PGT). Even though the widespread use of PGT from TE biopsy helped to decrease the interval from the beginning of the AR intervention to pregnancy, especially in older patients, in AR, there are still many concerns about the application of this invasive methodology in all cycles. Therefore, recently, researchers started to study the use of cell free DNA (cfDNA) released by the blastocyst in its culture medium to perform PGT, in a method called non-invasive PGT (niPGT). The development of a niPGT would bring the diagnostics power of conventional PGT, but with the advantage of being potentially less harmful to the embryo. Its implementation in clinical practice, however, is under heavy discussion since there are many unknowns about the technique, such as the origin of the cfDNA or if this genetic material is a true representative of the actual ploidy status of the embryo. Available data indicates that there is high correspondence between results observed in TE biopsies and the ones observed from cfDNA, but these results are still contradictory and highly debatable. In the present review, the advantages and disadvantages of niPGT are presented and discussed in relation to tradition TE biopsy-based PGT. Furthermore, there are also presented some other possible non-invasive tools that could be applied in the selection of the best embryo, such as quantification of other molecules as quality biomarkers, or the use artificial intelligence (AI) to identify the best embryos based on morphological and/or morphokitetic parameters.

Transvaginal ultrasound-guided oocyte retrieval in cattle: State-of-the-art and its impact on the in vitro fertilization embryo production outcome

Transvaginal ultrasound-guided oocyte retrieval (commonly called OPU) and in vitro embryo production (IVP) in cattle has shown significant progress in recent years, in part, as a result of a better understanding of the full potential of these tools by end users. The combination of OPU and IVP (OPU-IVP) has been successfully and widely commercially used worldwide. The main advantages are a greater number of embryos and pregnancies per unit of time, faster genetic progress due to donor quick turn around and more elite sires mating combinations, larger spectrum of female age (calves, prepuberal, heifer, cow) and condition (open, pregnant) from which to retrieve oocytes, a reduced number of sperm (even sexed) required to fertilize the oocytes, among other benefits. OPU-IVP requires significant less donor preparation in comparison to conventional embryo transfer (<50% of usual FSH injections needed) to the extent of no stimulating hormones (FSH) are necessary. Donor synchronization, stimulation, OPU technique, oocyte competence, embryo performance, and its impact on cryopreservation and pregnancy are discussed.

Extracellular vesicles from human Fallopian tubal fluid benefit embryo development in vitro

STUDY QUESTION

Do extracellular vesicles (EVs) from human Fallopian tubes exert an influence on early embryo development in vitro?

SUMMARY ANSWER

Human Fallopian tube EVs carrying miRNAs increase murine embryo viability in vitro.

WHAT IS KNOWN ALREADY

Oviductal EVs (oEVs) are recently identified key players in embryo-oviduct interactions that contribute to successful pregnancy in vivo. Their absence in current in vitro systems may partly explain the suboptimal embryo development observed; therefore, further knowledge is needed about their impact on early embryos.

STUDY DESIGN SIZE DURATION

The oEVs were isolated from the luminal fluid of human Fallopian tubes using ultracentrifugation. We cocultured oEVs with murine two-cell embryos until the blastocyst stage. The study was conducted between August 2021 and July 2022.

PARTICIPANTS/MATERIALS SETTING METHODS

A total of 23 premenopausal women were recruited for Fallopian-tubes collection, and the oEVs were isolated. The micro RNA (miRNA) contents were detected using high-throughput sequencing and their target genes and effects were analyzed. After in vitro culture with or without oEVs, the blastocyst and hatching rates were recorded. Furthermore, for the blastocysts formed, we assessed the total cell number, inner cell mass proportion, reactive oxygen species (ROS) level, number of apoptotic cells, and mRNA expression levels of genes involved in development.

MAIN RESULTS AND THE ROLE OF CHANCE

EVs were successfully isolated from the human Fallopian tubal fluid and the concentrations were evaluated. A total of 79 known miRNAs were identified from eight samples that had been sequenced, all involved in various biological processes. The blastocyst rate, hatching rate, as well as total cell number of blastocysts were significantly increased in the oEVs-treated groups (P < 0.05 versus untreated), while the proportion of inner cell mass showed no significant difference between groups. ROS levels and apoptotic cell proportions were decreased in the oEVs-treated groups (P < 0.05 versus untreated). The genes, Actr3 (actin-related protein 3), Eomes (eomesodermin), and Wnt3a (Wnt family member 3A) were upregulated in blastocysts in the oEVs-treated group.

LARGE SCALE DATA

Data are available from Gene Expression Omnibus: Accession number: GSE225122.

LIMITATIONS REASONS FOR CAUTION

The Fallopian tubes in the current study were collected from patients with uterine fibroids (the reason they underwent hysterectomy), and this pathological condition may affect the characteristics of EVs in luminal fluid. Also, owing to restrictions for ethical reasons, an in vitro co-culture system using murine embryos was used instead of human embryos, and the findings may not be transferable.

WIDER IMPLICATIONS OF THE FINDINGS

Deciphering miRNA contents in human oEVs and providing new evidence that oEVs benefit embryo development in vitro will not only increase our knowledge on embryo-oviduct communication but also potentially improve ART outcomes.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the National Key Research and Development Project of China (2021YFC2700603). No competing interests are declared.

Small-extracellular vesicles and their microRNA cargo from porcine follicular fluids: the potential association with oocyte quality

Background

Ovarian follicular fluids (FFs) contain several kinds of regulatory factors that maintain a suitable microenvironment for oocyte development. Extracellular vesicles (EVs) are among the factors that play essential roles in regulating follicle and oocyte development through their cargo molecules that include microRNAs (miRNAs). This study aimed to investigate small-EV (s-EV) miRNAs in porcine FFs and their potential association with oocyte quality.

Methods

Individual aspirated oocytes were stained with lissamine green B stain (LB), a vital stain for oocyte quality, and each oocyte was classified as high-quality (unstained; HQ) or low-quality (stained; LQ). FFs corresponding to oocytes were pooled together into HQ and LQ groups. Small-EVs were isolated from FFs, characterized, and their miRNA cargo was identified using the Illumina NovaSeq sequencing platform. Additionally, s-EVs from the HQ and LQ groups were utilized to investigate their effect on oocyte development after co-incubation during in vitro maturation.

Results

A total of 19 miRNAs (including miR-125b, miR-193a-5p, and miR-320) were significantly upregulated, while 23 (including miR-9, miR-206, and miR-6516) were downregulated in the HQ compared to the LQ group. Apoptosis, p53 signaling, and cAMP signaling were among the top pathways targeted by the elevated miRNAs in the HQ group while oocyte meiosis, gap junction, and TGF-beta signaling were among the top pathways targeted by the elevated miRNAs in the LQ group. The supplementation of small-EVs during maturation does not affect the oocyte developmental rates. However, LQ s-EVs increase the proportion of oocytes with homogeneous mitochondrial distribution and decrease the proportion of heterogeneous distribution.

Conclusion

Our findings indicated that FF-EVs contain different miRNA cargos associated with oocyte quality and could affect the mitochondrial distribution patterns during oocyte maturation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00723-1.

Loss of Renewal of Extracellular Vesicles: Harmful Effects on Embryo Development in vitro

Background

Methods

Results

Conclusion

Can nanomaterials support the diagnosis and treatment of human infertility? A preliminary review

Human infertilities are disorders that afflict many people all over the world. Both male and female reproductive systems must work together in a precise and coordinated manner and infertility has a wide range of problems for this system. Recent advances in nanomedicine immensely helped design the diagnostic and therapeutic approaches to alleviate human infertility in both sexes. Nanoscience has recently been used by researchers to increase the detection limit of infertility-related biomarkers via fabricating sensitive nanobiosensors for detecting follicle-stimulating hormone (FSH), luteinizing hormone (LH), anti-müllerian hormone (AMH), pregnancy-associated plasma protein-A (PAPP-A), progesterone, and testosterone. At the same time, a variety of nanostructures, including magnetic nanoparticles (i.e., zinc nanoparticles, cerium nanoparticles, gold nanoparticles, silver nanoparticles), nano-vitamins, extracellular vesicles, and spermbots, have shown promising outcomes in the treatment of human infertilities. Despite recent advancements, some nanostructures might have toxic effects on cells, especially germ cells, and must be optimized with the right ingredients, such as antioxidants, nutrients, and vitamins, to obtain the right strategy to treat and detect human infertilities. This review presents recent developments in nanotechnology regarding impairments still faced by human infertility. New perspectives for further use of nanotechnology in reproductive medicine studies are also discussed. In conclusion, nanotechnology, as a tool for reproductive medicine, has been considered to help overcome current impairments.

Seminal Plasma: Relevant for Fertility?

Seminal plasma (SP), the non-cellular component of semen, is a heterogeneous composite fluid built by secretions of the testis, the epididymis and the accessory sexual glands. Its composition, despite species-specific anatomical peculiarities, consistently contains inorganic ions, specific hormones, proteins and peptides, including cytokines and enzymes, cholesterol, DNA and RNA-the latter often protected within epididymis- or prostate-derived extracellular vesicles. It is beyond question that the SP participates in diverse aspects of sperm function pre-fertilization events. The SP also interacts with the various compartments of the tubular genital tract, triggering changes in gene function that prepares for an eventual successful pregnancy; thus, it ultimately modulates fertility. Despite these concepts, it is imperative to remember that SP-free spermatozoa (epididymal or washed ejaculated) are still fertile, so this review shall focus on the differences between the in vivo roles of the SP following semen deposition in the female and those regarding additions of SP on spermatozoa handled for artificial reproduction, including cryopreservation, from artificial insemination to in vitro fertilization. This review attempts, including our own results on model animal species, to critically summarize the current knowledge of the reproductive roles played by SP components, particularly in our own species, which is increasingly affected by infertility. The ultimate goal is to reconcile the delicate balance between the SP molecular concentration and their concerted effects after temporal exposure in vivo. We aim to appraise the functions of the SP components, their relevance as diagnostic biomarkers and their value as eventual additives to refine reproductive strategies, including biotechnologies, in livestock models and humans.