Cumulus oophorus complexes favor physiologic selection of spermatozoa for intracytoplasmic sperm injection

Identification of Differentially Expressed mRNAs and miRNAs and Related Regulatory Networks in Cumulus Oophorus Complexes Associated with Fertilization

Cumulus oophorus complexes (COCs) are the first extracellular barriers that sperm must pass through to fuse with oocytes, which have an important role in oocyte maturation and fertilization. However, little is known about the molecular mechanisms of COCs involved in fertilization. In this study, COCs were collected and then randomly divided into a test group that interacted with sperm and a control group that did not interact with sperm. Then, the total RNA was extracted; RNA transcriptome and small RNA libraries were prepared, sequenced, and analyzed. The results showed that 1283 differentially expressed genes (DEGs), including 560 upregulated and 723 downregulated genes. In addition, 57 differentially expressed miRNAs (DEMIs) with 35 upregulated and 22 downregulated were also detected. After the RNA-seq results were verified by RT-qPCR, 86 effective DEGs and 40 DEMIs were finally screened and a DEMI-DEG regulatory network was constructed. From this, the top ten hub target genes were HNF4A, SPN, WSCD1, TMEM239, SLC2A4, E2F2, SIAH3, ADORA3, PIK3R2, and GDNF, and they were all downregulated. The top ten hub DEMIs were miR-6876-5p, miR-877-3p, miR-6818-5p, miR-4690-3p, miR-6789-3p, miR-6837-5p, miR-6861-5p, miR-4421, miR-6501-5p, and miR-6875-3p, all of which were upregulated. The KEGG signaling pathway enrichment analysis showed that the effective DEGs were significantly enriched in the calcium, AMPK, and phospholipase D signaling pathways. Our study identified several DEGs and DEMIs and potential miRNA-mRNA regulatory pathways in COCs and these may contribute to fertilization. This study may provide novel insights into potential biomarkers for fertilization failure.

Microfluidic chip as a promising evaluation method in assisted reproduction: A systematic review

The aim of assisted reproductive technology (ART) is to select the high-quality sperm, oocytes, and embryos, and finally achieve a successful pregnancy. However, functional evaluation is hindered by intra- and inter-operator variability. Microfluidic chips emerge as the one of the most powerful tools to analyze biological samples for reduced size, precise control, and flexible extension. Herein, a systematic search was conducted in PubMed, Scopus, Web of Science, ScienceDirect, and IEEE Xplore databases until March 2023. We displayed and prospected all detection strategies based on microfluidics in the ART field. After full-text screening, 71 studies were identified as eligible for inclusion. The percentages of human and mouse studies equaled with 31.5%. The prominent country in terms of publication number was the USA (n = 13). Polydimethylsiloxane (n = 49) and soft lithography (n = 28) were the most commonly used material and fabrication method, respectively. All articles were classified into three types: sperm (n = 38), oocytes (n = 20), and embryos (n = 13). The assessment contents included motility, counting, mechanics, permeability, impedance, secretion, oxygen consumption, and metabolism. Collectively, the microfluidic chip technology facilitates more efficient, accurate, and objective evaluation in ART. It can even be combined with artificial intelligence to assist the daily activities of embryologists. More well-designed clinical studies and affordable integrated microfluidic chips are needed to validate the safety, efficacy, and reproducibility. Trial registration: The protocol was registered in the Open Science Frame REGISTRIES (identification: osf.io/6rv4a).

Only the Best of the Bunch-Sperm Preparation Is Not Just about Numbers

In this Seminar, we present an overview of the current and emerging methods and technologies for optimizing the man and the sperm sample for fertility treatment. We argue that sperms are the secret to success, and that there are many avenues for improving both treatment and basic understanding of their role in outcomes. These outcomes encompass not just whether treatment is successful or not, but the wider intergenerational health of the offspring. We discuss outstanding challenges and opportunities of new technologies such as microfluidics and artificial intelligence, including potential pitfalls and advantages. This article aims to provide a comprehensive overview of the importance of sperm in fertility treatment and suggests future directions for research and innovation.

Exposure to Cumulus Cell Secretome Improves Sperm Function: New Perspectives for Sperm Selection In Vitro

In the literature, there is a well-known correlation between poor semen quality and DNA sperm integrity, which can turn into negative outcomes in terms of embryo development and clinical pregnancy. Sperm selection plays a pivotal role in clinical practice, and the most widely used methods are mainly based on sperm motility and morphology. The cumulus oophorus complex (COC) during natural fertilization represents a barrier that spermatozoa must overcome to reach the zona pellucida and fertilize the oocyte. Spermatozoa that can pass through the COC have better structural and metabolic characteristics as well as enhanced acrosome reaction (AR). The present study aimed to evaluate the exposure of sperm to cumulus cell secretome during swim-up treatment (SUC) compared with the routinely used swim-up method (SU). To determine the effectiveness of this method, biological factors critical for the ability of sperm to fertilize an oocyte, including capacitation, AR, tyrosine phosphorylation signature, DNA integrity, and mitochondrial functionality, were assessed. The SUC selection assures recovery of high-quality spermatozoa, with enhanced mitochondrial functionality and motility compared with both SU-selected and unselected (U) sperm. Furthermore, using this modified swim-up procedure, significantly reduced sperm DNA damage (p < 0.05) was detected. In conclusion, the SUC approach is a more physiological and integrated method for sperm selection that deserves further investigation for its translation into clinical practice.

Clinical and neonatal outcomes of using a modified micro cryotube for cryopreservation of small numbers of spermatozoa for TESA-ICSI cycles

Cryopreservation of a small number of human spermatozoa is still a major challenge for embryologists. The aim of this study was to evaluate the clinical pregnancy and neonatal outcomes of intracytoplasmic sperm injection (ICSI) using a modified micro cryotube as freezing carrier for freezing small numbers of human spermatozoa collected by testicular sperm aspiration (TESA). We conducted a retrospective study to analyses the ICSI outcomes of using frozen-thawed few testicular spermatozoa in males with obstructive azoospermia (OA) from June 2017 to June 2021. Of 155 ICSI treatment cycles, 79 cycles were allocated to frozen sperm group and a modified micro cryotube was used for freezing testicular sperm, 76 cycles were allocated as fresh sperm group. No significant differences were observed in fertilization rate, good quality embryo rate, and blastocyst rate between the frozen sperm group and fresh sperm group (P > 0.05). Similarly, in the fresh embryo transfer cycles plus the first frozen-thawed embryo transfer cycles, the total clinical pregnancy rate (54.43% vs 57.89%), implantation rate (46.08% vs 49.47%), miscarriage rate (13.95% vs 13.64%) and live birth rate (45.57% vs 48.68%) were not statistically different between the frozen and fresh sperm groups (P > 0.05). In addition, there was no statistical differences in the mean gestational age (38.33weeks ± 1.74 vs 37.89weeks ± 1.87), preterm delivery rate (5.56% vs 10.81%), mean birth weight at delivery (3026.50 g ± 577.64 vs 2977.56 g ± 528.93), and low birth weight (12.50% vs 19.51%) between the two groups (P > 0.05 in all cases). Modified micro cryotube for cryopreservation of rare testicula rretrieved spermatozoa did not negatively affect the pregnancy and neonatal outcomes in TESA-ICSI cycles. The presented method may be a useful alternative for cryopreservation of small numbers of human spermatozoa in clinical setting.

Molecular Chaperone HSPA2 Distribution During Hyaluronic Acid Selection in Human Sperm

During fertilization, sperm hyaluronidase activity is essential for spermatozoa to successfully penetrate the hyaluronic acid-enriched extracellular matrix of the cumulus cells. Since molecular chaperones, as the heat shock protein A2, are typically involved in bringing hyaluronic acid receptors to the cell surface, here we evaluated the presence and spatial location of HSPA2 on human spermatozoa based on its hyaluronic acid binding capacity. This study included 16 normozoospermic sperm samples from volunteering donors. The location of HSPA2 was studied in cells before and after 1-h incubation under capacitating conditions, as well as in spermatozoa selected according to their ability of binding to hyaluronic acid. Our results showed no significant differences in HSPA2 immunofluorescent cells before and after 1 h of incubation in capacitating conditions. Nevertheless, after hyaluronic acid selection, the percentage of HSPA2-labelled cells increased significantly, indicating that the interaction with hyaluronic acid may induce the unmasking of HSPA2 epitopes. Furthermore, after swim-up and hyaluronic acid selection, spermatozoa presented a highly immunostained equatorial band with a homogeneous fluorescence throughout the acrosomal region. This distribution has been previously suggested to have important implications in male fertility. Noteworthy, a homogeneous fluorescence among the acrosomal region with a more intense labelling at the apical region was observed only in hyaluronic acid bound sperm cells, which may be associated with primary gamete recognition. Our findings suggest that the hyaluronic acid selection technique and HSPA2 biomarker should be considered candidates to complement the classic seminal analysis before recommending an appropriate assisted reproduction technique.

Comparative study between SpermSlow™ hyaluronan and traditional sperm selection in ICSI outcome

The role of hyaluronic acid (HA) as a 'physiologic selector' is also well recognized in vitro: it has been demonstrated that spermatozoa that bind to immobilized HA in vitro are those having completed their plasma membrane remodelling, and cytoplasmic and meiotic maturation. Sperm selection using HA has been expected to increase the implantation rate in intracytoplasmic sperm injection (ICSI) cycles. This work was designed to evaluate an alternative product for slowing sperm motility that contains HA and measures its outcomes: fertilization rate, embryo quality, and implantation and pregnancy rates. The present study found a positive drift in embryo quality that was statistically significant in the study group (SpermSlow™-ICSI) with teratozoospermia compared with PVP-ICSI in the same group. There were differences in the pregnancy rate (statistically insignificant in normozoospermia, asthenozoospermia, oligozoospermia, and teratozoospermia) in the SpermSlow-ICSI group compared with PVP-ICSI. The HA-ICSI technique in assisted reproduction technology (ART) is an important way to improve fertilization rate, embryo quality, and pregnancy rate.

Microfluidic devices employing chemo- and thermotaxis for sperm selection can improve sperm parameters and function in patients with high DNA fragmentation

Conventional sperm processing uses centrifugation has a negative effect on sperm parameters and DNA integrity. We designed and fabricated a novel microfluid device based on chemotaxis and thermotaxis, and compared it with the swim-up method. Twenty normal samples with high DNA fragmentation were included. Each sample was divided into four groups: Group 1, control, Group 2: sperm selection by thermotaxis, Group 3: sperm selection by chemotaxis, and Group 4: sperm selection with thermotaxis and chemotaxis. We used cumulus cells in a microfluid device to create chemotaxis, and, two warm stages to form a temperature gradient for thermotaxis. The spermatozoa were assessed based on the concentration, motility, and fine morphology using Motile Sperm Organelle Morphology Examination, mitochondrial membrane potential (MMP), acrosome reaction (AR), and sperm DNA fragmentation. Concentration (22.40 ± 5.39 vs. 66.50 ± 19.21; p < 0.001) and DNA fragmentation (12.30 ± 3.96% vs. 17.95 ± 2.89%; p < 0.001) after selection in the chemotaxis and thermotaxis microfluid device were significantly lower than control group. The progressive motility (93.75 ± 4.39% vs. 75.55 ± 5.86%, p < 0.001), normal morphology (15.45 ± 2.50% vs. 10.35 ± 3.36, p < 0.001), MMP (97.65 ± 1.81% vs. 94 ± 3.89%, p = 0.02), and AR status (79.20 ± 5.28% vs. 31.20 ± 5.24%, p < 0.001) in the chemotaxis and thermotaxis microfluid device were significantly increased compared to control group. According to these findings, spermatozoa that have penetrated the cumulus oophorus have better morphology and motility, as well as acrosome reactivity and DNA integrity.

Sperm Adhesion Molecule 1 (SPAM1) Distribution in Selected Human Sperm by Hyaluronic Acid Test

The failures of binding to the oocyte zona pellucida are commonly attributed to defects in the sperm recognition, adhesion, and fusion molecules. SPAM1 (sperm adhesion molecule 1) is a hyaluronidase implicated in the dispersion of the cumulus-oocyte matrix. Therefore, the aim of this study was to characterize the SPAM1 distribution in the different physiological conditions of human sperm. Specifically, we evaluated the location of the SPAM1 protein in human sperm before capacitation, at one and four hours of capacitation and after hyaluronic acid (HA) selection test by fluorescence microscopy. Sperm bound to HA were considered mature and those that crossed it immature. Our results detected three SPAM1 fluorescent patterns: label throughout the head (P1), equatorial segment with acrosomal faith label (P2), and postacrosomal label (P3). The data obtained after recovering the mature sperm by the HA selection significantly (p < 0.05) highlighted the P1 in both capacitation times, being 79.74 and 81.48% after one hour and four hours, respectively. Thus, the HA test identified that human sperm require the presence of SPAM1 throughout the sperm head (P1) to properly contact the cumulus-oocyte matrix. Overall, our results provide novel insights into the physiological basis of sperm capacitation and could contribute to the improvement of selection techniques.

Application of ultrasound markers measured at different time points of COH cycle in the prediction of ovarian response for individualised ovulation induction

The purpose of this study was to evaluate the predictive value of ultrasound markers measured at different time points of the controlled ovarian hyperstimulation (COH) cycle on ovarian response and outcome indicators in the IVF-ET cycle. According to the oestrogen level and the number of retrieved oocytes, patients who planned for COH treatment were separated into low-response group, normal and high-response group. The ovarian stromal artery flow parameters on the day of pituitary down-regulation, day 1, day 7, day 10, and the day of hCG injection were collected prospectively. We also have collected the data of cumulus oophorus count on the day of hCG injection by transvaginal sonography. Compared with the low-response group, on the first day of the COH cycle PI, RI, and S/D were lower in the high-response group than they were in the low-response group (p < .05). PSV and EDV were significantly higher in the high-response group than they were in the low-response group (p < .01), and the PSV on the first day of the COH cycle have statistical significance in predicting the number of high-quality embryos. The number of cumulus oophorus on the day of hCG injection has statistical significance in predicting the number of oocytes retrieved and fertilised oocytes. We conclude that the ovarian stromal artery flow parameters on the first day of the COH cycle and cumulus oophorus count on hCG injection day can serve as efficient indicators for an early assessment of ovarian response and individualised ovulation induction.IMPACT STATEMENTWhat is already known on this subject? AMH, AFC, and the age of the patient are well-known effective parameters for the evaluation of ovarian response, but these are insufficient and full of individual differences. Some researchers have investigated the value of colour Doppler ultrasound and cumulus oophorus in assessing ovarian response, but no definitive conclusion has been reached.What do the results of this study add? The hemodynamic parameters of ovarian stromal artery on the first day of the COH cycle and the number of cumulus oophorus on the day of hCG injection detected by Transvaginal Colour Doppler Sonography (TV-CDS) could be used to predict the ovarian response.What are the implications of these findings for clinical practice and/or further research? Ovarian stromal artery flow parameters and cumulus oophorus detected by TV-CDS can potentially be offered as a complementary parameter for ovarian reserve.

Controlled spermatozoa-oocyte interaction improves embryo quality in sheep

The current protocols of in vitro fertilization and culture in sheep rely on paradigms established more than 25 years ago, where Metaphase II oocytes are co-incubated with capacitated spermatozoa overnight. While this approach maximizes the number of fertilized oocytes, on the other side it exposes them to high concentration of reactive oxygen species (ROS) generated by active and degenerating spermatozoa, and positively correlates with polyspermy. Here we set up to precisely define the time frame during which spermatozoa effectively penetrates and fertilizes the oocyte, in order to drastically reduce spermatozoa-oocyte interaction. To do that, in vitro matured sheep oocytes co-incubated with spermatozoa in IVF medium were sampled every 30 min (start of incubation time 0) to verify the presence of a fertilizing spermatozoon. Having defined the fertilization time frame (4 h, data from 105 oocytes), we next compared the standard IVF procedures overnight (about 16 h spermatozoa/oocyte exposure, group o/nIVF) with a short one (4 h, group shIVF). A lower polyspermic fertilization (> 2PN) was detected in shIVF (6.5%) compared to o/nIVF (17.8%), P < 0.05. The o/nIVF group resulted in a significantly lower 2-cell stage embryos, than shIVF [34.6% (81/234) vs 50.6% (122/241) respectively, P < 0.001]. Likewise, the development to blastocyst stage confirmed a better quality [29% (70/241) vs 23.5% (55/234), shIVF vs o/nIVF respectively] and an increased Total Cell Number (TCN) in shIVF embryos, compared with o/n ones. The data on ROS have confirmed that its generation is IVF time-dependent, with high levels in the o/nIVF group. Overall, the data suggest that a shorter oocyte-spermatozoa incubation results in an improved embryo production and a better embryo quality, very likely as a consequence of a shorter exposure to the free oxygen radicals and the ensuing oxidative stress imposed by overnight culture.

Simulating nature in sperm selection for assisted reproduction

Sperm selection in the female reproductive tract (FRT) is sophisticated. Only about 1,000 sperm out of millions in an ejaculate reach the fallopian tube and thus have a chance of fertilizing an oocyte. In assisted reproduction techniques, sperm are usually selected using their density or motility, characteristics that do not reflect their fertilization competence and, therefore, might result in failure to fertilize the oocyte. Although sperm processing in in vitro fertilization (IVF) and intrauterine insemination (IUI) bypasses many of the selection processes in the FRT, selection by the cumulus mass and the zona pellucida remain intact. By contrast, the direct injection of a sperm into an oocyte in intracytoplasmic sperm injection (ICSI) bypasses all natural selection barriers and, therefore, increases the risk of transferring paternal defects such as fragmented DNA and genomic abnormalities in sperm to the resulting child. Research into surrogate markers of fertilization potential and into simulating the natural sperm selection processes has progressed. However, methods of sperm isolation - such as hyaluronic acid-based selection and microfluidic isolation based on sperm tactic responses - use only one or two parameters and are not comparable with the multistep sperm selection processes naturally occurring within the FRT. Fertilization-competent sperm require a panel of molecules, including zona pellucida-binding proteins and ion channel proteins, that enable them to progress through the FRT to achieve fertilization. The optimal artificial sperm selection method will, therefore, probably need to use a multiparameter tool that incorporates the molecular signature of sperm with high fertilization potential, and their responses to external cues, within a microfluidic system that can replicate the physiological processes of the FRT in vitro.

Laser-assisted selection of immotile spermatozoa has no effect on obstetric and neonatal outcomes of TESA-ICSI pregnancies

BACKGROUND

Azoospermic patients have benefited from both epididymal and testicular spermatozoa intracytoplasmic sperm injection (ICSI) treatment and lasers have been used to identify viable, immotile spermatozoa before the procedure. There are limited studies on the safety of laser-assisted selection of immotile spermatozoa. The aim of this study was to investigate the impact of laser-assisted selection of immotile spermatozoa on the obstetric and neonatal outcomes after ICSI.

METHODS

A retrospective comparative study was conducted on outcomes of ICSI cycles with testicular spermatozoa from June 2014 to June 2018. Of 132 cycles, 33 were allocated to the test group and oocytes were injected with immotile spermatozoa selected by laser, 99 cycles were allocated as control group.

RESULTS

Compared with the control group, no significant differences were found in the pregnancy, implantation, miscarriage and live birth rates in the test group in either fresh or frozen transfer cycles. The cumulative live birth rate in the test group was 69.70%, which was slightly higher than in the control group (60.61%), but this was not statistically different. There were no differences in the average gestational age, premature birth rate, neonatal birth weight, and the malformation rate between the test and control groups (P > 0.05). In addition, the obstetric outcome between the two groups were not different (P > 0.05).

CONCLUSIONS

No negative effect on perinatal and neonatal outcomes was seen by using laser-assisted selection of immotile spermatozoa for TESA-ICSI. This study endorses the use of laser-assisted selection of viable spermatozoa for ICSI cycles.

Single-blind clinical trial: Sperm selection based on capacity to pass through cumulus oophorous column improves ICSI outcomes

BACKGROUND

Sperm selection procedures for future strategies that aim to select normal spermatozoa with intact DNA to improve intracytoplasmic sperm injection (ICSI) outcomes are in early developing stage.

OBJECTIVES

The objective is to find out whether the sperm selection procedure based on the ability of spermatozoa to traverse the cumulus cells could improve clinical outcomes of ICSI technique in infertile couples with male factor etiology.

MATERIALS AND METHODS

For this single-blind clinical trial, mature metaphase II oocytes were retrieved from 150 couples with male factor infertility, male age lower than 45 years and female age under 38 years. These couples were divided into two groups. In control group (n = 75), spermatozoa processed by density gradient centrifugation (DGC) were used to inject the oocytes. In the study group (n = 75), the oocytes were divided into sibling groups. In one sibling group (DGC), the oocytes were inseminated with DGC-processed spermatozoa while in the other group (DGC-CC), they were inseminated with DGC-processed spermatozoa that passed cumulus oophorous column.

RESULTS

Mean fertilization and embryo quality were significantly higher in DGC-CC group compared to DGC and control group. In addition, mean of chemical pregnancy (52.27% vs. 34.14%; p = 0.05), clinical pregnancy based on sac (52.27% vs. 32.92%; p = 0.03), clinical pregnancy with heart beat (52.27% vs. 25.60%; p = 0.003) and ongoing pregnancy (43.18% vs. 21.95%; p = 0.02) rates were significantly higher in DGC-CC group compared to control group.

CONCLUSION

Sperm selection based on integrated systems such as DGC and ability to pass through cumulus oophorous column could improve clinical outcomes of ICSI in couples with male factor infertility.

Microfluidic Systems for Assisted Reproductive Technologies: Advantages and Potential Applications

Microfluidic technologies have emerged as a powerful tool that can closely replicate the in-vivo physiological conditions of organ systems. Assisted reproductive technology (ART), while being able to achieve successful outcomes, still faces challenges related to technical error, efficiency, cost, and monitoring/assessment. In this review, we provide a brief overview of the uses of microfluidic devices in the culture, maintenance and study of ovarian follicle development for experimental and therapeutic applications. We discuss existing microfluidic platforms for oocyte and sperm selection and maintenance, facilitation of fertilization by in-vitro fertilization/intracytoplastimc sperm injection, and monitoring, selection and maintenance of resulting embryos. Furthermore, we discuss the possibility of future integration of these technologies onto a single platform and the limitations facing the development of these systems. In spite of these challenges, we envision that microfluidic systems will likely evolve and inevitably revolutionize both fundamental, reproductive physiology/toxicology research as well as clinically applicable ART.

Sperm morphology: What implications on the assisted reproductive outcomes?

OBJECTIVE

To evaluate the impact of sperm morphology (SM) on laboratory and pregnancy outcomes in conventional intracytoplasmic sperm injection (c-ICSI) cycles, using the egg donation model to minimize female confounding variables.

MATERIALS AND METHODS

We retrospectively collected data of oocyte donation cycles from October 2016 to February 2020. Median seminal parameters, total (1-2-3PN) fertilization rate (FR), 2PN FR, cleavage rate (CR), implantation rate (IR), pregnancy rate (PR), miscarriage rate (MR), and live birth rate (LBR) were collected. The study population was divided into three groups: Group 1 with SM < 4%, Group 2 with SM between 4% and 6%, and Group 3 with SM > 6%.

RESULTS

Of 741 fresh ICSI cycles and 4507 warmed oocytes were included. Male age was 46.0 (31.0-72.0) years, and recipients' age was 44.0 (29.0-54.0) years. Normal SM was 5.0% (1.0%-15.0%). Male age was negatively correlated with normal SM (P = .002; Rho -0.113). Oocyte survival rate was 83.3% (16.7%-100.0%). Total FR was 75.0% (11.1%-100.0%), 2PN FR was 66.7% (11.1%-100.0%) %, and CR was 100% (0.0%-100%). Comparing samples with SM > 6% and those with SM < 4%, 2PN FR was significantly higher in the first group (P = .04). No significant associations were found among groups in terms of CR. IR was 27.7%, resulting significantly higher when normal SM was > 6% (P < .01). Clinical PR was 36.0%, MR was 23.9%, and LBR was 25.9%. PR and LBR were significantly higher in samples with normal SM > 6%, compared to other groups (P = .02 and P < .01, respectively).

CONCLUSIONS

Although c-ICSI technique allows the embryologist to select the best quality spermatozoa, male factor plays a key role in achieving successful assisted reproductive outcomes. Normal SM has been shown to have implications not only for laboratory outcomes, in terms of fertilization, but also for clinical findings, as regards implantation, pregnancy, and live birth.