Comet assay of cumulus cells and spermatozoa DNA status, and the relationship to oocyte fertilization and embryo quality following ICSI

The association between age-related infertility and deoxyribonucleic acid (DNA) integrity parameters of granulosa cells and lymphocytes

This study aimed to investigate the association between deoxyribonucleic acid (DNA) integrity parameters and advanced maternal age (AMA)-related infertility. The granulosa cells and the lymphocytes obtained from 119 infertile women were recruited. Patients were divided into two groups: the AMA group (≥35 years, n = 26) and the non-AMA group (<35 years, n = 93). The tail length, tail moment and tail DNA percentage were evaluated as the DNA integrity parameters using comet assay. Infertility duration (p=.001), luteinising hormone (p=.01) and progesterone levels (p<.0001) were higher and smoking was more prevalent in the AMA group (p=.001). AMA group was stimulated with higher gonadotropin doses (p=.04) and had decreased anti-mullerian hormone levels (p<.0001). All of DNA integrity parameters were distributed homogenously between the groups; however, the tail length of lymphocytes was higher (p=.02) in the AMA group. Fertilisation was lower (p=.02), oocyte quality was tended to be poor (p=.03) and blastocyst transfer was lower in the AMA group (p=.03). Embryo quality was distributed homogenously between the groups. Implantation, clinical pregnancy and live birth rates were similar between the groups. Impact StatementWhat is already known on this subject? Advanced maternal age (AMA)-related infertility is associated with diminished ovarian reserve and alteration in follicular environment resulting in poor oocyte quality; however, the exact pathophysiologic mechanism is not clear.What do the results of this study add? Tail length, tail deoxyribonucleic acid (DNA) percentage, tail moment of granulosa cells were nonsignificantly higher in the AMA group compared to younger patients. All of the DNA integrity parameters of lymphocytes were nonsignificantly higher; however, only tail length of lymphocytes was statistically higher in the AMA group than the non-AMA group. A positive correlation was observed between DNA integrity parameters of lymphocytes and body mass index. There were no correlations between DNA integrity parameters of granulosa cells and lymphocyte and infertility duration, gonadotropin dose, duration of ovarian stimulation, oocyte score, embryo score, basal hormone levels and anti-mullerian hormone levels.What are the implications of these findings for clinical practice and/or further research? Our findings offer new insight for further understanding the role of granulosa cells in mediating the poor reproductive outcome of ageing patients. Understanding the mechanisms of ovarian ageing and poor oocyte quality in women with AMA may help to identify specific targets for improving oocyte quality with ageing.

Effect of DNA damage of cumulus oophorus cells and lymphocytes analyzed by alkaline comet assay on oocyte quality and intracytoplasmic sperm injection success among patients with polycystic ovary syndrome

AIM

Cumulus oophorus cells (COC) exhibit a close relationship with the oocytes. We aimed to determine the role of the DNA integrity of COC and lymphocytes on the oocyte and embryo quality and intracytoplasmic sperm injection (ICSI) success.

METHODS

The COC obtained with the mechanical denudation of each oocyte and the lymphocytes obtained on oocyte retrieval day from 69 infertile polycystic ovary syndrome (PCOS) patients were used. The tail length, tail moment and tail DNA percentage were evaluated using an alkaline comet assay. The oocytes and embryos were graded. Clinical pregnancy was defined as the presence of a gestational sac with a beating heart.

RESULTS

All of the DNA integrity parameters of the COC and lymphocytes were similar between the good and poor quality oocytes and between the good and poor quality embryos. There was no relationship between the DNA damage parameters and the fertilization and clinical pregnancy. The day 2 hormone levels, body mass index and age were negatively correlated with the DNA integrity parameters. No links were found between the embryo and oocyte scores and the DNA damage parameters.

CONCLUSION

The DNA integrity of the COC and lymphocytes did not seem to be related to the oocyte and embryo quality and ICSI success.

Varicocele repair in patients prepared for intracytoplasmic sperm injection: To do or not to do?

PURPOSE

This study sought to evaluate the impact of varicocele repair on intracytoplasmic sperm injection outcomes.

PATIENTS AND METHODS

A prospective comparative study was conducted at the Assisted Reproduction Unit, International Islamic Center for Population Studies and Researches, Al-Azhar University. This study included 100 non-azoospermic infertile men with a history of varicocele who were scheduled for intracytoplasmic sperm injection, half of them had already undergone prior subinguinal varicocelectomy at least 12 months prior to ICSI without clinically evident recurrence (treated group 1), and the other half has any grade of an unrepaired clinical varicocele (untreated group 2) at sperm injection. All cases were clinically evaluated and eligible for analysis by using inclusion and exclusion criteria. ICSI outcomes compared between the two groups, including fertilisation rate, embryo development rate and pregnancy outcome.

RESULTS

Our study did not show any significant difference between treated and untreated groups regarding the mean values of fertilisation (0.7759 ± 0.2708 vs. 0.7119 ± 0.3057, p = 0.2708), embryo development (0.7759 ± 0.2708 vs. 0.6991 ± 0.3211, p = 0.1990) or different embryo grades. There was no statistically significant difference between groups regarding pregnancy occurrence rates (p = 0.0928).

CONCLUSION

Infertile men scheduled for ICSI do not seem to benefit from varicocele repair as regard to the outcomes of ICSI.

Evaluation of DNA Damage of Mare Granulosa Cells Before and After Cryopreservation Using a Chromatin Dispersion Test

DNA fragmentation of granulosa cells might be related to developmental competence of the equine oocyte. Granulosa cells are commonly stored before DNA fragmentation assessment, but the effect of preservation methods on this parameter remains unexplored. The aim of this study was to evaluate whether or not cryopreservation of granulosa cells affects the DNA damage. Equine oocytes were recovered from postmortem ovaries of five mares. Granulosa cells were washed by centrifugation and then analyzed (control) or stored in cryovials following four different protocols: P1 = directly plunged in liquid nitrogen (LN₂) and then stored at -80°C; P2 = LN₂/-80°C adding cryoprotectants (7.5% ethylene glycol + 7.5% dimethyl sulfoxide); P3 = -80°C; P4 = -80°C + cryoprotectants. Granulosa cell samples were processed with the prototype D3-Ovoselect, Halotech DNA, Spain), and DNA was visualized under fluorescence microscopy. High, low, and total DNA fragmentation percentages were compared among treatments by analysis of variance. Results were expressed as mean ± standard error. No significant differences (P > .05) were found among treatments and the control group. Therefore, the four conservation protocols could be considered equally efficient for DNA preservation of granulosa cells from mare oocytes. In conclusion, cryopreservation of granulosa cells in any of the four protocols used adequately preserved the DNA for further analysis.

A systematic review and meta-analysis to determine the effect of sperm DNA damage on in vitro fertilization and intracytoplasmic sperm injection outcome

Sperm DNA damage is prevalent among infertile men and is known to influence natural reproduction. However, the impact of sperm DNA damage on assisted reproduction outcomes remains controversial. Here, we conducted a meta-analysis of studies on sperm DNA damage (assessed by SCSA, TUNEL, SCD, or Comet assay) and clinical pregnancy after IVF and/or ICSI treatment from MEDLINE, EMBASE, and PUBMED database searches for this analysis. We identified 41 articles (with a total of 56 studies) including 16 IVF studies, 24 ICSI studies, and 16 mixed (IVF + ICSI) studies. These studies measured DNA damage (by one of four assays: 23 SCSA, 18 TUNEL, 8 SCD, and 7 Comet) and included a total of 8068 treatment cycles (3734 IVF, 2282 ICSI, and 2052 mixed IVF + ICSI). The combined OR of 1.68 (95% CI: 1.49–1.89; P < 0.0001) indicates that sperm DNA damage affects clinical pregnancy following IVF and/or ICSI treatment. In addition, the combined OR estimates of IVF (16 estimates, OR = 1.65; 95% CI: 1.34–2.04; P < 0.0001), ICSI (24 estimates, OR = 1.31; 95% CI: 1.08–1.59; P = 0.0068), and mixed IVF + ICSI studies (16 estimates, OR = 2.37; 95% CI: 1.89–2.97; P < 0.0001) were also statistically significant. There is sufficient evidence in the existing literature suggesting that sperm DNA damage has a negative effect on clinical pregnancy following IVF and/or ICSI treatment.

Measuring Sperm DNA Fragmentation and Clinical Outcomes of Medically Assisted Reproduction: A Systematic Review and Meta-Analysis

Sperm DNA fragmentation has been associated with reduced fertilization rates, embryo quality, pregnancy rates and increased miscarriage rates. Various methods exist to test sperm DNA fragmentation such as the sperm chromatin structure assay (SCSA), the sperm chromatin dispersion (SCD) test, the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labelling (TUNEL) assay and the single cell gel electrophoresis (Comet) assay. We performed a systematic review and meta-analysis to assess the value of measuring sperm DNA fragmentation in predicting chance of ongoing pregnancy with IVF or ICSI. Out of 658 unique studies, 30 had extractable data and were thus included in the meta-analysis. Overall, the sperm DNA fragmentation tests had a reasonable to good sensitivity. A wide variety of other factors may also affect the IVF/ICSI outcome, reflected by limited to very low specificity. The constructed hierarchical summary receiver operating characteristic (HSROC) curve indicated a fair discriminatory capacity of the TUNEL assay (area under the curve (AUC) of 0.71; 95% CI 0.66 to 0.74) and Comet assay (AUC of 0.73; 95% CI 0.19 to 0.97). The SCSA and the SCD test had poor predictive capacity. Importantly, for the TUNEL assay, SCD test and Comet assay, meta-regression showed no differences in predictive value between IVF and ICSI. For the SCSA meta-regression indicated the predictive values for IVF and ICSI were different. The present review suggests that current sperm DNA fragmentation tests have limited capacity to predict the chance of pregnancy in the context of MAR. Furthermore, sperm DNA fragmentation tests have little or no difference in predictive value between IVF and ICSI. At this moment, there is insufficient evidence to recommend the routine use of sperm DNA fragmentation tests in couples undergoing MAR both for the prediction of pregnancy and for the choice of treatment. Given the significant limitations of the evidence and the methodological weakness and design of the included studies, we do urge for further research on the predictive value of sperm DNA fragmentation for the chance of pregnancy after MAR, also in comparison with other predictors of pregnancy after MAR.

Follicular steroid hormones as markers of oocyte quality and oocyte development potential

CONTEXT:

Various components of follicular fluid are suggested as biochemical predictors of oocyte quality. Previous studies of follicular steroid hormone levels have shown disparate results when related with fertilization outcomes.

AIM:

The objective of the study was to relate the levels of steroid hormones of each individual follicle with oocyte maturation, fertilization results, embryo quality, and pregnancy rates.

SETTINGS AND DESIGN:

Prospective cohort study in a university hospital.

METHODS:

In 31 patients, who underwent intracytoplasmic sperm injection, it was performed an ultrasound guided aspiration of follicular fluid of the first two mature follicles from each ovary. Follicular levels of estradiol, progesterone, testosterone, and dehydroepiandrosterone sulfate were measured by chemiluminescent immunoassay.

STATISTICAL ANALYSIS:

Generalized estimating equation model.

RESULTS:

In follicular fluids with mature oocyte presence, in normal as well as in failed fertilization, there was a positive correlation between follicular testosterone and progesterone (r = 0.794, P = 0.0001 and r = 0.829, P = 0.0001). Progesterone levels were higher in cases of normal fertilization compared to failed fertilization (P = 0.003). B quality embryos came from oocytes immersed in follicular fluids with higher estradiol values and higher estradiol/progesterone and estradiol/testosterone ratios than those of C quality (P = 0.01; P = 0.0009; P = 0.001). Estradiol levels were higher in patients who achieved pregnancy (P = 0.02).

CONCLUSION:

The analysis of follicular hormone composition could be considered as an additional tool in oocyte selection.

Sperm DNA fragmentation measured by Halosperm does not impact on embryo quality and ongoing pregnancy rates in IVF/ICSI treatments

Sperm DNA fragmentation (SDF) has been proposed to be one of the main markers regarding male infertility. A prospective study was performed to assess primarily whether sperm DNA damage has any impact on embryological data and secondarily on pregnancy rates. This prospective study evaluated the sperm DNA damage in fresh ejaculated sperm samples from couples undergoing IVF/ICSI treatments, using the improved SCD method, known as Halosperm(®) . The results were evaluated by performing statistical analysis with the statistical package of SPSS v17. A total of 156 fresh semen samples derived from 156 couples undergoing 156 IVF/ICSI cycles. From the 156 couples, 139 finally reached the embryo transfer (ET) procedure. Overall, SDF did not correlate with embryological data, while ongoing pregnancy rate/ET was 21.6%. SDF only correlated with sperm characteristics. After the categorisation of SDF (≤35% and >35%), according to the specific references of the method used, embryological data were comparable as also ongoing pregnancy rates. Using the SCD method, sperm DNA damage is associated neither with embryological data nor to pregnancy rates. However, we should not rule out the fact that extremely high DNA damages are associated with total pregnancy failure.

Multifactorial analysis of the follicular environment is predictive of oocyte morphology in cattle

Numerous attempts have been recently made in the search for a reliable, fast and noninvasive assay for selection of oocytes suitable for in vitro embryo production. Potential markers have been described in the follicle such as follicular fluid (FF) or cumulus cells (CCs). However, the reported findings are contradictory, which may reflect the complexity of metabolism of the ovarian follicle. In the present experiment, a data set from individual follicles of known diameter was obtained: cumulus-oocyte complex (COC) morphology, fatty acid composition and glucose concentration in FF as well as apoptotic index in CCs. The obtained data was statistically analyzed either separately (univariate analysis) or simultaneously (multivariate analysis) to examine its predictive value in morphology assessment of bovine COCs. Although the univariate analysis yielded a complex relation system of the selected parameters, no clear outcome could be established. In multivariate analysis, the concentration of the four fatty acids (C16:0, C16:1, C18:1cis9, C22:5n3) and Δ⁹-desaturase (16) as well as elongase activities were selected as covariates. This allowed prediction of the morphology of a COC with an accuracy of 72%, which is the most interesting finding of the experiment. The present study indicates that the multifactorial model comprising of selected parameters related to the follicle appeared more effective in predicting the morphology of a bovine COC, which may improve the effectiveness of in vitro production systems.

Integrity of human sperm DNA assessed by the neutral comet assay and its relationship to semen parameters and clinical outcomes for the IVF-ET program

Objective

To explore potential relationships between sperm DNA integrity and both semen parameters and clinical outcomes.

Methods

Semen analysis of 498 samples was performed according to the 2010 criteria of the World Health Organization. The sperm DNA fragmentation Index (DFI) of the semen samples was assessed using a neutral comet assay.

Results

Sperm DFI showed a significant correlation with semen parameters, including the patient's age, sperm viability, motility, morphology, and number of leukocytes (p<0.05). The sperm DFI values for asthenozoospermic (15.2%), oligoteratozoospermic (18.3%), asthenoteratozoospermic (17.5%), and oligoasthenoteratozoospermic semen samples (21.3%) were significantly higher than that observed in normozoospermic semen samples (10.5%, p<0.05). A sperm DFI value of 14% was used as a threshold of sperm DFI in assessing whether DNA was highly damaged. In 114 IVF-ET cycles, the fertilization rate of the sperm DFI <14% group (70 cycles, 61.7%) was significantly higher than that observed for the ≥14% group (44 cycles, 55.3%), but there was no difference in the other clinical outcomes between the two groups. In the ≥14% group, the pregnancy rates of the ICSI cycles (40.0%) and half-ICSI (44.0%) were higher than conventional IVF cycles (30.7%), but the difference was not statistically significant.

Conclusion

Along with the conventional semen analysis, the sperm DFI assessed using the comet assay was shown to improve the quality of the semen evaluation. To evaluate the precise effect of ICSI on pregnancy rates in the patients who demonstrate high sperm DFI values, further study is necessary.

The levels of steroid hormones and cytokines in individual follicles are not associated with the fertilization outcome after intracytoplasmic sperm injection

OBJECTIVE

To investigate the association between the levels of two steroid hormones and eight cytokines in fluids from individual follicles and the fertilization outcome of the oocytes derived from the same follicles.

DESIGN

Prospective study.

SETTING

University hospital.

PATIENT(S)

Forty-three women participating in intracytoplasmic sperm injection (ICSI)/ET cycles.

INTERVENTION(S)

The ovarian stimulation followed the multidose GnRH antagonist protocol. ICSI was performed in mature oocytes. The concentrations of estradiol, progesterone, tumor necrosis factor-alpha, interleukin (IL) -1beta, IL-6, vascular endothelial growth factor, leptin, basic fibroblast growth factor, epidermal growth factor, and insulin-like growth factor-I were measured by immunoassay methods in the follicles from which the mature oocytes were derived.

MAIN OUTCOME MEASURE(S)

The concentrations of the above hormones and cytokines in individual follicles and the fertilization outcome of the oocytes derived from the same follicles.

RESULT(S)

The intrafollicular concentrations of the above factors were not significantly associated with the fertilization outcome. These factors were not correlated with embryo quality, with the exception of leptin, which was weakly associated with embryo score (R = 0.276).

CONCLUSION(S)

The intrafollicular concentrations of the above factors cannot predict the fertilization outcome after ICSI.

The comet assay in male reproductive toxicology

Due to our lifestyle and the environment we live in, we are constantly confronted with genotoxic or potentially genotoxic compounds. These toxins can cause DNA damage to our cells, leading to an increase in mutations. Sometimes such mutations could give rise to cancer in somatic cells. However, when germ cells are affected, then the damage could also have an effect on the next and successive generations. A rapid, sensitive and reliable method to detect DNA damage and assess the integrity of the genome within single cells is that of the comet or single-cell gel electrophoresis assay. The present communication gives an overview of the use of the comet assay utilising sperm or testicular cells in reproductive toxicology. This includes consideration of damage assessed by protocol modification, cryopreservation vs the use of fresh sperm, viability and statistics. It further focuses on in vivo and in vitro comet assay studies with sperm and a comparison of this assay with other assays measuring germ cell genotoxicity. As most of the de novo structural aberrations occur in sperm and spermatogenesis is functional from puberty to old age, whereas female germ cells are more complicated to obtain, the examination of male germ cells seems to be an easier and logical choice for research and testing in reproductive toxicology. In addition, the importance of such an assay for the paternal impact of genetic damage in offspring is undisputed. As there is a growing interest in the evaluation of genotoxins in male germ cells, the comet assay allows in vitro and in vivo assessments of various environmental and lifestyle genotoxins to be reliably determined.

DNA damage of human spermatozoa in assisted reproduction: origins, diagnosis, impacts and safety

Sperm DNA contributes half the offspring's genomic material and abnormal DNA can lead to derangements in the reproductive process. Normal sperm genetic material is required for successful fertilization, as well as for further embryo and fetal development that will result in a healthy child. Thus, the damage to sperm DNA is critical in assisted reproductive techniques which are increasingly used to treat infertile couples. There has been improving data about the effects of human sperm DNA damage or fragmentation. As well, increasing knowledge concerning the effects of DNA damage on embryo and fetal development has been attained. This review aims to summarize the present knowledge on the impact of human sperm cell DNA damage on male infertility and outcome in the context of safety.

Sibling oocyte submission to IVF and ICSI in unexplained infertility patients: a potential assay for gamete quality

In order to reduce total fertilization failure in unexplained infertility, sibling oocytes were submitted to both conventional IVF and intracytoplasmic sperm injection (ICSI). Two groups of ICSI embryos were compared in unexplained infertility patients: those derived from ICSI when IVF had failed to fertilize, and those derived from ICSI while their sibling oocytes were fertilized by IVF. The outcome of oocytes fertilized exclusively by ICSI (essential ICSI, n = 749) was compared with those fertilized both by IVF and ICSI (non-essential ICSI, n = 957) in all IVF patients treated for unexplained infertility at the Hadassah Hospital (1999-2002). The latter group was further subdivided into ICSI and IVF embryos. Total fertilization rate was 54%. Fertilization rates by ICSI were lower in the essential ICSI compared with the non-essential ICSI group, at 65 and 73% (P < 0.025). Pregnancy rates per embryo transfer in the essential ICSI group (49%), ICSI derived embryos group (55%) and IVF derived embryos (44%) from the non-essential ICSI group, were similar. Implantation rates were lower in the essential ICSI group as compared with the non-essential ICSI group (21 versus 32% respectively; P < 0.05) and 26% for IVF embryos. In conclusion, essential ICSI was associated with lower fertilization and implantation rates.