Traditional intracytoplasmic sperm injection provides equivalent outcomes compared with human zona pellucida-bound selected sperm injection

Sperm Selection Using Zona Pellucida-Binding Enhanced Embryo Morphokinetic and Clinical Outcomes in ICSI: A Sibling Oocytes Study

The objective was to investigate the embryo morphokinitics using a time-lapse monitoring (TLM) system and assessment of clinical outcomes following intracytoplasmic sperm injection (ICSI) with zona pellucida (ZP)-bound sperm selection and conventional methods. A total of 371 metaphase II (MII) oocytes from 50 ICSI cycles were studied. Sibling oocytes were randomly divided into control (n = 199) and ZP-bound group (n = 172). All resulting zygotes were cultured and monitored in the TLM system up to Day 3 after ICSI. Fertilization rate, early embryo development, and clinical outcomes were evaluated. No significant differences were found in fertilization rate, time-lapse qualitative and quantitative measures, pronuclear fading time (PNF) t2, t3, t4, t5, t6, and t7 (times of cleavage to 2, 3, 4, 5, 6, and 7 cells), respectively. However, the t8 (time of cleavage to eight cells) and cc3 (duration of third cell cycle) revealed a significant difference between control and ZP-bound groups (p < .05). A significant difference between the two groups (p < .05) in the rates of Grade A embryos (according to Basile algorithm), chemical pregnancy, clinical pregnancy, and implantation was observed. Sperm selection using biological materials, such as ZP, improved both embryo quality and pregnancy outcomes, despite not affecting the early embryo development and morphokinetic parameters up to t8. This prospective randomized sibling oocyte trial was registered in October 2020 to January 2022 (IRCT20200705048021N1).

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.

Use of zona pellucida-bound spermatozoa as a natural selection in improvement of ICSI outcomes: A systematic review and meta-analysis

Zona pellucida (ZP)-bound spermatozoa have normal morphology and motility and can enhance the ICSI outcomes. Selection of zona pellucida-bound spermatozoa is recently considered to find functional spermatozoa for ICSI. This study reviewed the efficacy of ZP-bound sperm selection on the ICSI outcomes includes fertilisation rate, embryo quality, embryo transfer rate and clinical pregnancy rate. The databases searched include PubMed, Scopus and Cochrane databases up to January 2019. All research reports with full text and in English language that addressing the relation between ZP-sperm selection and ICSI outcomes were included. Fifty studies were suitable after screening of the 845 identified articles. After exclusions, five of these studies were included. Meta-analytic pooling of data indicated no association between the ICSI outcomes and ZP-bound sperm selection except a marginal effect on implantation rate. Eliminating one study indicated that ZP-bound sperm selection technique improves embryo quality, implantation rate and clinical pregnancy rate. This study revealed that ZP-bound sperm selection produces only a slight improvement in implantation rate. However, further studies with a large number of couples must be done to clarify the potential beneficial effect of ZP-bound spermatozoa on ICSI outcomes.

Advanced sperm selection techniques for assisted reproduction

BACKGROUND

Assisted reproductive technologies (ART) including in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI), combine gametes to enhance the probability of fertilisation and pregnancy. Advanced sperm selection techniques are increasingly employed in ART, most commonly in cycles utilising ICSI. Advanced sperm selection techniques are proposed to improve the chance that structurally intact and mature sperm with high DNA integrity are selected for fertilisation. Strategies include selection according to surface charge; sperm apoptosis; sperm birefringence; ability to bind to hyaluronic acid; and sperm morphology under ultra-high magnification. These techniques are intended to improve ART outcomes.

OBJECTIVES

To evaluate the effectiveness and safety of advanced sperm selection techniques on ART outcomes.

SEARCH METHODS

We conducted a systematic search of electronic databases (Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL via the Cochrane Register of Studies Online, MEDLINE, Embase, PsycINFO, Cumulative Index to Nursing and Allied Health Literature (CINAHL); trials registers (ClinicalTrials.gov, Current Controlled Trials, and the World Health Organization International Clinical Trials Registry Platform); conference abstracts (Web of Knowledge); and grey literature (OpenGrey) for relevant randomised controlled trials (RCTs). We handsearched the reference lists of included studies and similar reviews. The search was conducted in June 2018.

SELECTION CRITERIA

We included RCTs comparing advanced sperm selection techniques versus standard IVF, ICSI, or another technique. We excluded studies of intracytoplasmic morphologically selected sperm injection (IMSI), as they are subject to a separate Cochrane Review. Primary outcomes measured were live birth and miscarriage per woman randomly assigned. Secondary outcome measures included clinical pregnancy per woman randomly assigned. Secondary adverse events measured included miscarriage per clinical pregnancy and foetal abnormality.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility and risk of bias and extracted data. Any disagreements were resolved by consultation with a third review author. We consulted study investigators to resolve queries. Risk ratios (RRs) were calculated with 95% confidence intervals (CIs). We combined studies using a fixed-effect model. We evaluated the quality of the evidence using GRADE methods.

MAIN RESULTS

We included eight RCTs (4147 women). The quality of evidence ranged from very low to low. The main limitations were imprecision, performance bias, and attrition bias.Hyaluronic acid selected sperm-intracytoplasmic sperm injection (HA-ICSI) compared to ICSITwo RCTs compared the effects of HA-ICSI versus ICSI on live birth. The quality of the evidence was low. There may be little or no difference between groups: 25% chance of live birth with ICSI versus 24.5% to 31% with HA-ICSI (RR 1.09, 95% CI 0.97 to 1.23, 2903 women, I2 = 0%, low-quality evidence). Three RCTs reported on miscarriage. HA-ICSI may decrease miscarriage per woman randomly assigned: 7% chance of miscarriage with ICSI versus 3% to 6% chance with HA-ICSI (RR 0.61, 95% CI 0.45 to 0.83, 3005 women, I2 = 0%, low-quality evidence) and per clinical pregnancy: 20% chance of miscarriage with ICSI compared to 9% to 16% chance with HA-ICSI (RR 0.62, 95% CI 0.46 to 0.82, 1065 women, I2 = 0%, low-quality evidence). Four RCTs reported on clinical pregnancy. There may be little or no difference between groups: 37% chance of pregnancy with ICSI versus 34% to 40% chance with HA-ICSI (RR 1.00, 95% CI 0.92 to 1.09, 3492 women, I2 = 0%, low-quality evidence).HA-ICSI compared to SpermSlowOne RCT compared HA-ICSI to SpermSlow. The quality of the evidence was very low. We are uncertain whether HA-ICSI improves live birth compared to SpermSlow (RR 1.13, 95% CI 0.64 to 2.01, 100 women) or clinical pregnancy (RR 1.05, 95% CI 0.66 to 1.68, 100 women). We are uncertain whether HA-ICSI reduces miscarriage per woman (RR 0.80, 95% CI 0.23 to 2.81, 100 women) or per clinical pregnancy (RR 0.76, 95% CI 0.24 to 2.44, 41 women).Magnetic-activated cell sorting (MACS) compared to ICSIOne RCT compared MACS to ICSI for live birth; three reported clinical pregnancy; and two reported miscarriage. The quality of the evidence was very low. We are uncertain whether MACS improves live birth (RR 1.95, 95% CI 0.89 to 4.29, 62 women) or clinical pregnancy (RR 1.05, 95% CI 0.84 to 1.31, 413 women, I2 = 81%). We are also uncertain if MACS reduces miscarriage per woman (RR 0.95, 95% CI 0.16 to 5.63, 150 women, I2 = 0%) or per clinical pregnancy (RR 0.51, 95%CI 0.09 to 2.82, 53 women, I2=0)Zeta sperm selection compared to ICSIOne RCT evaluated Zeta sperm selection. The quality of the evidence was very low. We are uncertain of the effect of Zeta sperm selection on live birth (RR 2.48, 95% CI 1.34 to 4.56, 203 women) or clinical pregnancy (RR 1.82, 95% CI 1.20 to 2.75, 203 women). We are also uncertain if Zeta sperm selection reduces miscarriage per woman (RR 0.73, 95% CI 0.16 to 3.37, 203 women) or per clinical pregnancy (RR 0.41, 95% CI 0.10 to 1.68, 1 RCT, 62 women).MACS compared to HA-ICSIOne RCT compared MACS to HA-ICSI. This study did not report on live birth. The quality of the evidence was very low. We are uncertain of the effect on miscarriage per woman (RR 1.52, 95% CI 0.10 to 23.35, 78 women) or per clinical pregnancy (RR 1.06, 95% CI 0.07 to 15.64, 37 women). We are also uncertain of the effect on clinical pregnancy (RR 1.44, 95% CI 0.91 to 2.27, 78 women).

AUTHORS' CONCLUSIONS

The evidence suggests that sperm selected by hyaluronic acid binding may have little or no effect on live birth or clinical pregnancy but may reduce miscarriage. We are uncertain of the effect of Zeta sperm selection on live birth, clinical pregnancy, and miscarriage due principally to the very low quality of the evidence for this intervention. We are uncertain of the effect of the other selection techniques on live birth, miscarriage, or pregnancy.Further high-quality studies, including the awaited data from the identified ongoing studies, are required to evaluate whether any of these advanced sperm selection techniques can be recommended for use in routine practice.

Improving ICSI: A review from the spermatozoon perspective

Intracytoplasmic sperm injection (ICSI) is the most frequently applied method for fertilization making the process of identifying the perfect spermatozoon fundamental. Herein we offer a critical and thorough presentation on the techniques reported regarding (i) handling and preparing semen samples, (ii) identifying and 'fishing' spermatozoa, and (iii) improving key factors, such as motility for a successful ICSI practice. These approaches are suggested to make the process easier and more effective especially in atypical and challenging circumstances. Furthermore, we present an epigrammatic opinion-where appropriate-based upon our collective experience. Techniques such as intracytoplasmic morphologically selected sperm injection, hyaluronic binding, polarized light microscopy, and annexin V agent identification for comparing sperm cells and their chromatin integrity are analyzed. Moreover, for the demanding cases of total sperm immotility the use of the hypoosmotic swelling test, methylxanthines, as well as the option of laser assisted immotile sperm selection are discussed. Finally, we refer to the employment of myoinositol as a way to bioreactively improve ICSI outcome for oligoasthenoteratozoospermic men. The diversity and the constant development of novel promising techniques to improve ICSI from the spermatozoon perspective, is certainly worth pursuing. The majority of the techniques discussed are still a long way from being established in routine practices of the standard IVF laboratory. In most cases an experienced embryologist could yield the same results. Although some of the techniques show great benefits, there is a need for large scale multicenter randomized control studies to be conducted in order to specify their importance before suggesting horizontal application. Taking into consideration the a priori invasive nature of ICSI, when clinical application becomes a possibility we need to proceed with caution and ensure that in the pursuit for innovation we are not sacrificing safety and the balance of the physiological and biological pathways of the spermatozoon's dynamic.

ABBREVIATIONS

ICSI: intracytoplasmic sperm injection; IVF: in vitro fertilization; PGD: reimplantation genetic diagnosis; IVM: in vitro maturation; HCV/HIV: hepatitis C virus/human immunodeficiency virus; IMSI: intracytoplasmic morphologically selected sperm injection; DGC: density gradient centrifugations; S-U: swim-up; ART: assisted reproduction technology; IUI: intrauterine insemination; PVP: polyvinylpyrrolidone; HA: hyaluronic acid; MSOME: motile sperm organelle morphology examination; ZP: zona pellucida; MACS: magnetic activation cell sorting; HOST: hypo-osmotic swelling test; TESE: testicular sperm extraction; MMP: mitochondrial membrane potential; OAT: oligoasthenoteratozoospermic.

Outcomes of intracytoplasmic sperm injection using the zona pellucida-bound sperm or manually selected sperm

PURPOSE

Zona pellucida (ZP)-bound sperm used for intracytoplasmic sperm injection (ICSI) enhances embryo quality, implantation, and clinical pregnancy rates. This study aimed to assess the pregnancy outcomes and clinical significance of ICSI with ZP-bound sperm.

METHOD

A total of 84 infertile couples who underwent cycles of ICSI following failed in vitro fertilization between June 2012 and February 2014 were enrolled and randomized (1:1): in the treatment group, ICSI was performed using ZP-bound sperm; in the control group, ICSI was performed in a standard manner. Rates of fertilization, cleavage, high-quality embryos, and clinical pregnancy were compared between the two groups.

RESULTS

There were no significant differences in age, infertile period, gonadotrophin dose, number of metaphase II oocytes, and number of embryo transfers between the two groups (P > 0.05). The clinical pregnancy rate was higher in the treatment group than in the control group, but without statistical significance (60.5 vs. 47.6 %, P > 0.05). No significant differences in the rates of fertilization and cleavage were observed (83.0 vs. 81.6 %, and 96.3 vs. 96.5 %, both P > 0.05), but higher rates of high-quality embryos and useable embryos were observed with ZP-bound sperm compared with controls (66.1 vs. 50.8 % and 76.0 vs. 66.3 %, both P < 0.05).

CONCLUSIONS

ICSI using ZP-bound sperm might increase the embryo quality and number of useable embryos, possibly improving the clinical pregnancy outcome of ICSI.