Possible applications of a non-contact 1.48 μm wavelength diode laser in assisted reproduction technologies

The effects of photobiomodulation on the improvement of sperm parameters: A review study

The prevalence of male infertility has become a significant clinical concern worldwide, with a noticeable upward trend in recent times. The rates of fertilization and subsequent development of embryos are dependent on many parameters associated with the quality and viability of sperm. Photobiomodulation (PBM) is a promising approach with a great potential for translational applications in the treatment of spermatozoa exhibiting low quality and motility. In this study, a comprehensive analysis of the existing literature, specifically examining the mechanisms of action of PBM has been presented. Our objective was to enhance knowledge in the field of laser light therapy in order to promote the usage of irradiation in clinical settings in a more effective way. Within the realm of reproductive science, the utilization of PBM has been employed to enhance the metabolic processes, motility, and viability of spermatozoa. This is attributed to its advantageous effects on mitochondria, resulting in the activation of the mitochondrial respiratory chain and subsequent synthesis of ATP. This therapeutic approach can be highly advantageous in circumventing the reliance on chemical substances within the culture medium for spermatozoa while also facilitating the viability and motility of spermatozoa, particularly in circumstances involving thawing or samples with significant immotility.

Applications of laser technology in the manipulation of human spermatozoa

The application of laser technology in the field of assisted reproductive technology (ART) has experienced rapid growth over the past decades owing to revolutionary techniques such as intracytoplasmic sperm injection (ICSI), preimplantation genetic testing (PGT), and in vitro manipulation of gametes and embryos. For male gametes, in vitro manipulation techniques include spermatozoa selection, sorting, immobilization, and quality assessment. A number of studies have been conducted to investigate the application of different laser technologies in the manipulation of human spermatozoa. However, there is a lack of a unified understanding of laser application in the in vitro manipulation of sperm and safety considerations in ART and, subsequently, the inability to make clear and accurate decisions on the clinical value of these laser technologies. This review summarizes the advancements and improvements of laser technologies in the manipulation of human spermatozoa, such as photobiomodulation therapy, laser trap systems for sperm analysis and sorting, laser-assisted selection of immotile sperm and laser-assisted immobilization of sperm prior to ICSI. The safety of those technologies used in ART is also discussed. This review will provide helpful and comprehensive insight into the applications of laser technology in the manipulation of human spermatozoa.

Sperm Selection for ICSI: Do We Have a Winner?

In assisted reproductive technology (ART), the aim of sperm cells’ preparation is to select competent spermatozoa with the highest fertilization potential and in this context, the intracytoplasmic sperm injection (ICSI) represents the most applied technique for fertilization. This makes the process of identifying the perfect spermatozoa extremely important. A number of methods have now been developed to mimic some of the natural selection processes that exist in the female reproductive tract. Although many studies have been conducted to identify the election technique, many doubts and disagreements still remain. In this review, we will discuss all the sperm cell selection techniques currently available for ICSI, starting from the most basic methodologies and continuing with those techniques suitable for sperm cells with reduced motility. Furthermore, different techniques that exploit some sperm membrane characteristics and the most advanced strategy for sperm selection based on microfluidics, will be examined. Finally, a new sperm selection method based on a micro swim-up directly on the ICSI dish will be analyzed. Eventually, advantages and disadvantages of each technique will be debated, trying to draw reasonable conclusions on their efficacy in order to establish the gold standard method.

The effect of chemical treatment of the sheep embryo zona pellucida on the ability of blastocysts to hatch after vitrification and warming

BACKGROUND

The embryo release from the zona pellucida is of prerequisites of successful implantation.

OBJECTIVES

Regarding the negative impact of embryo cryopreservation on the blastocysts hatchability, the aim of the present study was to investigate the effects of treating embryonic zona pellucida with pronase or acidic Tyrode's solution (ATS) before morula formation on the viability, freezability, and hatchability of vitrified-warmed resulted blastocysts.

METHODS

In the first experiment, the zona pellucida of 3- and 4-day-old embryos were treated with the above compounds for 30 or 45 s. Then, the competency of the treated embryos to reach to blastocyst stage and the hatchability of resulting blastocysts were investigated. In the second experiment, the cryo-survivability and hatching rate of blastocysts resulting from 3-day-old embryos treated with pronase and ATS for 30 s were tested.

RESULTS

In the first experiment and in contrast to the 45 s exposure, 30-s exposure of embryos to pronase or ATS did not have negative effect on the viability and development of embryos to blastocyst stage. In the second experiment, the freezability of blastocysts derived from 3-day-old embryos treated with pronase and ATS for 30 s was not different from that of the control group. However, the hatching rate of the pronase group was significantly higher than that of the control group.

CONCLUSION

The results of the present study showed that reducing the thickness of zona pellucida of sheep embryos with pronase had no negative effect on the developmental competency and freezability of the treated embryos and improved the hatchability of vitrified-warmed blastocysts.

Laser-assisted cell removing (LACR) technology contributes to the purification process of the undifferentiated cell fraction during pluripotent stem cell culture

Purification of undifferentiated cells by removing differentiated parts is an essential step in pluripotent stem cell culture. This process has been traditionally performed manually using a fine glass capillary or plastic tip under a microscope, or by culturing in a selective medium supplemented with anti-differentiation inhibitors. However, there are several inevitable problems associated with these methods, such as contamination or biological side-effects. Here, we developed a laser-assisted cell removing (LACR) technology that enables precise, fast, and contact-less cell removal. Using LACR combined with computational image recognition/identification-discriminating technology, we achieved automatic cell purification (A-LACR). Practicability of A-LACR was evaluated by two demonstrations: selective removal of trophoblast stem (TS) cells from human iPS and TS cell co-cultures, and purification of undifferentiated iPS cells by targeting differentiated cells that spontaneously developed. Our results suggested that LACR technology is a novel approach for stem cell processing in regenerative medicine.

Morphokinetics of vitrified and warmed blastocysts predicts implantation potential

PURPOSE

It was studied whether morphokinetics of blastocoele re-expansion and hatching in vitrified-warmed blastocysts is predictive of implantation, clinical pregnancy, and live birth.

METHODS

In 144 patients aiming for single warmed blastocyst transfer, blastocysts were cultured in a new time-lapse system (Miri® TL) immediately after warming. Video sequences with an image interval of 5 min were annotated and the corresponding morphokinetic variables were correlated with pregnancy outcome. In detail, tRE (start of re-expansion), tCRE (completion of re-expansion), tAH (hatching from the manipulated zona pellucida), and presence of collapses were recorded.

RESULTS

In the pregnant group, tRE and tCRE were significantly lower (0.69 ± 0.45 h and 2.16 ± 0.94 h) as compared to the non-pregnant group (1.23 ± 1.08 h and 2.70 ± 1.20 h). Both variables and the duration of re-expansion (tCRE-tRE) allowed for distinction between "non-pregnant," "loss of pregnancy," and live birth/ongoing pregnancy. Presence and number of collapses showed no correlation with outcome.

CONCLUSIONS

Time-lapse imaging of vitrified-warmed blastocysts offers additional selection criteria allowing for prediction of implantation potential. As a consequence, cumulative pregnancy rate could be increased and time-to-pregnancy reduced.

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.

The impact of laser-assisted hatching on the outcome of frozen human embryo transfer cycles

Biochemical modifications of zona pellucida (ZP) result in zona hardening. Zona hardening (ZH) is induced by several factors such as advancing maternal age, in vitro culture conditions and cryopreservation and adversely effects implantation. The objective of the clinical study was to determine whether or not laser-assisted hatching (LAH) applied on day 3 frozen embryos improves the outcome of frozen embryo transfer (FET) cycles in patients with recurrent implantation failure and/or advanced female age. In total, 413 patients of different ages with recurrent implantation failure (maximum three cycles) were involved into the study. Patients were allocated randomly into LAH and control groups. On the day of FET, after thawing and just before FET, the ZP was thinned using a laser system. In the control group no treatment was applied on frozen embryo before transfer. The main outcome measures were clinical pregnancy rate. Overall, the results indicate a tendency that LAH increased (P = 0.08) clinical pregnancy. However, for patients older than 37 years, LAH increased pregnancy rates significantly (P = 0.03). In the LAH and control groups, the age of patients and the number of transferred embryos influenced pregnancy rates (P = 0.01). For patients older than 37 years, no effect of number of transferred embryos was detected (P = 0.14). The incidence of multiple pregnancies also increased in the LAH group (P = 0.01). In conclusion, in older woman, to overcome the negative effect of zona hardening, LAH could be performed on frozen embryos as a routine strategy before FET in frozen cycles in order to increase the possibility of pregnancy formation.

Chromosomal Aneuploidies and Early Embryonic Developmental Arrest

BACKGROUND

Selecting the best embryo for transfer, with the highest chance of achieving a vital pregnancy, is a major goal in current in vitro fertilization (IVF) technology. The high rate of embryonic developmental arrest during IVF treatment is one of the limitations in achieving this goal. Chromosomal abnormalities are possibly linked with chromosomal arrest and selection against abnormal fertilization products. The objective of this study was to evaluate the frequency and type of chromosomal abnormalities in preimplantation embryos with developmental arrest.

MATERIALS AND METHODS

This cohort study included blastomeres of embryos with early developmental arrest that were biopsied and analyzed by fluorescence in-situ hybridization (FISH) with probes for chromosomes 13, 16, 18, 21 and 22. Forty-five couples undergoing IVF treatment were included, and 119 arrested embryos were biopsied. All probes were obtained from the Kinderwunsch Zentrum, Linz, Austria, between August 2009 and August 2011.

RESULTS

Of these embryos, 31.6% were normal for all chromosomes tested, and 68.4% were abnormal. Eleven embryos were uniformly aneuploid, 20 were polyploid, 3 were haploid, 11 displayed mosaicism and 22 embryos exhibited chaotic chromosomal complement.

CONCLUSION

Nearly 70% of arrested embryos exhibit chromosomal errors, making chromosomal abnormalities a major cause of embryonic arrest and may be a further explanation for the high developmental failure rates during culture of the embryos in the IVF setting.

Equine Embryo Sexing and Ultrasonographic Foetal Sexing - Interests and Applicability

The ability to choose the sex of the offspring is of upmost economic importance for horse breeders. Unlike other species, horses present several reproductive peculiarities that interfere with assisted reproductive technologies used in other large animals (such as bovine) and make them difficult to apply. Thus, there is a great interest to determine the sex of the offspring as soon as possible. This has led to the development of several technologies to serve this purpose, which can be classified into two categories. One is equine embryo sexing by either non-invasive biotechnological methods, such as monitoring of X-linked enzymes before X chromosome inactivation and detection of sex-specific antigen, or by invasive biotechnological methods, such as cytogenetic analysis and polymerase chain reaction (PCR). The other one is equine foetus sexing using ultrasound scanning in different stages of its development (early, mid or late), by different approaches (transrectally or transabdominally). This can be performed with classic B-mode ultrasound machines or using 3D-mode and Doppler-mode scanners. This review article offers a comprehensive overview of the current status of these procedures as well as an assessment of their interests and applicability.

Risk of major congenital anomalies after assisted hatching: analysis of three-year data from the national assisted reproduction registry in Japan

OBJECTIVE

To assess perinatal risk of major congenital anomalies in children born after embryo transfer with assisted hatching (AH).

DESIGN

Retrospective cohort study.

SETTING

Not applicable.

PATIENT(S)

Cycles registered from 2010 to 2012 and conceived via single-embryo transfer were included for the analysis. Live births, still births after 22 weeks of gestation, and selectively terminated cases because of congenital anomalies were included.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Major congenital anomaly.

RESULT(S)

AH was performed in 35,488 cycles among 72,125 included cycles (49.2%). A total of 1,046 major congenital anomalies (1.4%) were identified (1.36% in AH group vs. 1.50% in non-AH group). Overall risks for major congenital anomalies were not significantly different between AH and non-AH groups adjusting for maternal age, calendar year, fetal sex, embryo stage at transfer, and status of cryopreservation. There were 1,009 cases of twins (1.5%) and 10 cases of triplets (0.015%) among all included cycles. No specific organ system demonstrated significant association between AH and non-AH groups. Subgroup analysis demonstrated no significant association between AH and non-AH groups in intracytoplasmic sperm injection cycles or in vitro fertilization in fresh cycles. Similar nonsignificant association was observed between early-cleavage or blastocyst stage at transfer in frozen-thawed cycles.

CONCLUSION(S)

Our results suggest that AH alone does not increase the risk of major congenital anomaly.

Preimplantation genetic diagnosis for beta-thalassemia using single-cell DNA analysis for codons 17 and 26 of beta-globin gene

BACKGROUND

Preimplantation genetic diagnosis (PGD) of monogenic autosomal hereditary disorders following assisted conception usually involves the removal of one or two blastomeres from preimplantation embryos. However, the amount of DNA from a single blastomere is insufficient to amplify the region of interest. Hence, the whole genome amplification (WGA) method is performed prior to amplifying the genes of interest before analysis of DNA material through polymerase chain reaction (PCR).

METHODS

In the present study we report that WGA from a single blastomere extracted from unwanted preimplantation human embryos (obtained from 10 infertile couples) could positively yield microgram quantities of amplified DNA allowing PCR analysis for codons 17 and 26 of the beta-globin gene that cause the beta-thalassemia disorder. We developed a rapid and highly specific technique of single-cell PCR to amplify a specific region on the beta-globin gene for codon 17 (AAG-->TAG) and codon 26 (GAG-->AAG) by using single-cell PCR.

RESULTS

About 249 bp of amplicon for codon 17 and about 200 bp of amplicon for codon 26 were successfully amplified. No mutations were observed. Analyzed embryos were not transferred back to patients because the embryos used as samples were wasted embryos.

CONCLUSIONS

Compared to other approaches for prenatal diagnosis, PGD is rapid and suitable as a noninvasive clinical tool for identifying genetic disorders for the purpose of reducing selective miscarriages and moral dilemmas. We opine that DNA extraction and amplification can be successfully performed by using single-cell PCR to diagnose genetic diseases before pregnancy.

Pregnancy after laser-assisted selection of viable spermatozoa before intracytoplasmatic sperm injection in a couple with male primary cilia dyskinesia

OBJECTIVE

To report an intracytoplasmatic sperm injection (ICSI) pregnancy achieved in a couple with male primary cilia dyskinesia (PCD) with viable sperm that were detected using a 1.48 microm wavelength diode laser.

DESIGN

Case report.

SETTING

University hospital.

PATIENT(S)

A 37-year-old man with infertility due to primary cilia dyskinesia; semen analysis revealed a severe oligoasthenoteratozoospermia with absence of motile spermatozoa. A 34-year-old healthy woman with a 10-year history of primary infertility.

INTERVENTION(S)

Selection of viable spermatozoa using the hypo-osmotic swelling (HOS) test or a 1.48 microm wavelength diode laser and subsequent ICSI.

MAIN OUTCOME MEASURE(S)

Sperm analysis. Fertilization and cleavage rates and pregnancy.

RESULT(S)

Semen samples showed no motile spermatozoa and high percentages of spermatozoa with curled flagella resembling HOS-reactive spermatozoa. To identify viable spermatozoa we used the HOS test or a 1.48 microm diode laser. The ICSI using HOS-selected spermatozoa resulted in two fertilized out of four oocytes (50%), and injection of laser-selected spermatozoa resulted in four fertilized out of seven oocytes (57%). The transfer of two frozen/thawed oocytes of the laser group led to a singleton pregnancy.

CONCLUSION(S)

Use of a noncontact diode laser for sperm viability assessment may be a useful alternative, especially in cases where the HOS test is not informative.

Assisted hatching is more effective when embryo quality was optimal in previous failed IVF/ICSI cycles

Assisted hatching (AH) was developed as a possible solution to repeated implantation failure. The aim of this analysis was to examine the relationship between the morphology of embryos in a previous cycle on outcome in a subsequent cycle with AH. A total of 175 AH cycles performed after previous failed ART without hatching were divided into group A with optimal and group B with suboptimal embryos transferred previously. The groups were similar in terms of demographic and cycle characteristics. In group A, there was a significant improvement (p<0.001) in implantation (28.8 vs 5.1%), clinical pregnancy (41.9 vs 12.1%) and live birth rate (38.5 vs 8.6%) compared with group B. The data suggest that the prognosis for treatment is better if AH is performed after failure despite optimal embryos compared with failure associated with suboptimal embryos and embryo quality is the most significant factor affecting outcome.

Exploring mechanochemical processes in the cell with optical tweezers

Force and torque, stress and strain or work are examples of mechanical and elastic actions which are intimately linked to chemical reactions in the cell. Optical tweezers are a light-based method which allows the real-time manipulation of single molecules and cells to measure their interactions. We describe the technique, briefly reviewing the operating principles and the potential capabilities to the study of biological processes. Additional emphasis is given to the importance of fluctuations in biology and how single-molecule techniques allow access to them. We illustrate the applications by addressing experimental configurations and recent progresses in molecular and cell biology.

Artificial shrinkage of blastocoeles using either a micro-needle or a laser pulse prior to the cooling steps of vitrification improves survival rate and pregnancy outcome of vitrified human blastocysts

BACKGROUND

Since we reported the first successful birth from a blastocyst vitrified using a cryoloop technique, our results showed that the survival rate of vitrified blastocysts was negatively correlated with the expansion of the blastocoele. We speculated that a large blastocoele may disturb the efficacy of vitrification. Therefore, we evaluated the effectiveness of artificial shrinkage (AS) of blastocoeles before vitrification, on increasing the survival rate of vitrified blastocysts.

METHODS

Supernumerary expanded blastocysts on day 5 were vitrified after AS, which was performed by puncturing the blastocoele with a micro-needle, or by making a hole in the blastocoele with a laser pulse. After warming, viable blastocysts (confirmed by re-expansion of the blastocoele) were transferred to patients with hormone replacement cycle. We compared these data with those of our previous report where AS was not carried out.

RESULTS

The survival rate was significantly higher (97.2%, 488/502) in this study than that of the previous report (86%). After 266 transferable cycles, 160 patients became pregnant (60.2%), which was significantly higher than our previous results (34.1%, 29/85). The implantation rate was 46.7% (209/448).

CONCLUSIONS

Our results revealed that the survival rate and the pregnancy rate of vitrified expanded and hatching blastocysts can be improved by using AS to collapse the blastocele before vitrification.