Mitochondrial DNA deletions and nuclear DNA fragmentation in testicular and epididymal human sperm

Surgically retrieved spermatozoa for ICSI cycles in non-azoospermic males with high sperm DNA fragmentation in semen

Intracytoplasmic sperm injection (ICSI) using surgically retrieved spermatozoa outside the classic context of azoospermia has been increasingly used to overcome infertility. The primary indications include high levels of sperm DNA damage in ejaculated spermatozoa and severe oligozoospermia or cryptozoospermia, particularly in couples with ICSI failure for no apparent reason. Current evidence suggests that surgically retrieved spermatozoa for ICSI in the above context improves  outcomes, mainly concerning pregnancy and miscarriage rates. The reasons are not fully understood but may be related to the lower levels of DNA damage in spermatozoa retrieved from the testis compared with ejaculated counterparts. These findings are consistent with the notion that excessive sperm DNA damage  can be a limiting factor responsible for the failure to conceive. Using testicular in preference of low-quality ejaculated spermatozoa bypasses post-testicular sperm DNA damage caused primarily by oxidative stress, thus increasing the likelihood of oocyte fertilization by genomically intact spermatozoa. Despite the overall favorable results, data remain limited, and mainly concern males with confirmed sperm DNA damage in the ejaculate. Additionally, information regarding the health of ICSI offspring resulting from the use of surgically retrieved spermatoa of non-azoospermic males is still lacking. Efforts should be made to improve the male partner's reproductive health for safer ICSI utilization. A comprehensive andrological evaluation aiming to identify and treat the underlying male infertility factor contributing to sperm DNA damage is essential for achieving this goal.

Microscopic Epididymal Sperm Aspiration (MESA) Should be Employed Over Testicular Sperm Extraction (TESE) Sperm Retrieval Surgery for Obstructive Azoospermia (OA)

INTRODUCTION

 Testicular sperm extraction (TESE) has been widely used as a sperm extraction surgery for azoospermia even for obstructive azoospermia (OA) because it does not require surgical skill. However, there are postoperative pain issues, and subsequent testicular atrophy and decreased testosterone levels may occur with TESE. This study examines the usefulness of microscopic epididymal sperm aspiration (MESA) for OA.

METHODS

 We studied 108 patients diagnosed with OA and treated with MESA at our institute between April 2004 and December 2021. The MESA was performed using a micropipette with a micropuncture technique under an operative microscope. When no sperm were present or motility was not observed, additional punctures to the epididymal tubule were performed.

RESULTS

 Motile sperm were recovered in all cases (108 cases). Of these, intracytoplasmic sperm injection (ICSI) using frozen-thawed sperm was performed in 101 cases and the normal fertilization rate was 76.2%. A total of 436 embryo transfer (ET) cycles were performed. The implantation rate per transfer cycle was 47.9%, the clinical pregnancy rate was 41.0%, and the live birth rate was 23.7%. The per-case live birth rate was 84.8%.

CONCLUSIONS

 MESA-ICSI has a very good fertilization rate, clinical pregnancy rate, and delivery rate. Furthermore, the patient's postoperative pain is less, the number of sperm collected is larger, the burden on the embryologist who processes the collected sperm is less, and ICSI can be easily attempted after frozen-thawed sperm. MESA rather than TESE should be employed for the OA subjects.

Analysis of the Growth and Development of Children Born with ICSI of Epididymal and Testicular Spermatozoa: A Propensity Matching Study

OBJECTIVE

The study aimed to evaluate whether singleton live births (at 0, 1, 6, 12, and 24 months) following intracytoplasmic sperm injection (ICSI) using sperm of different origins (ejaculated or non-ejaculated sperm) are associated with the growth and development of children born.

METHODS

This was a retrospective cohort study conducted at a single center from January 2016 to December 2019. Follow-up data of the children were obtained from the Jiangsu Province Maternal and Child database. A total of 350 singleton live births after fresh embryo transfer (ET) with ICSI were included. Based on the origin of the sperm, the patients were divided into two groups: the ejaculated group (n = 310) and the non-ejaculated group (n = 40). Propensity score matching was used to control for multiple baseline covariates, resulting in 80 singleton live births (ejaculated sperm) matched to 40 singleton live births (non-ejaculated). The non-ejaculated group was further divided into two subgroups: the PESA group (n = 23) and the TESA group (n = 17). The primary outcome of the study was the growth and development of children. Secondary outcomes included the 2PN rate, high-cleavage embryo rate, blastocyst formation rate, and others.

RESULTS

After matching parental age, BMI, occupation, and maternal serum AMH level, there was no significant difference found in the growth and development of children between the non-ejaculated and ejaculated group or the PESA group and TESA group, respectively. However, the 2PN rate and the blastocyst formation rate were higher in the ejaculated group compared to the non-ejaculated group (91.02 and 85.45, P = 0.002) and (67.37 and 56.06, P = 0.019), respectively. The high-quality cleavage embryo rate was also higher in the TESA group compared to the PESA group (85.06 and 65.63, P = 0.001).

CONCLUSION

This study suggests that there are no significant differences in the growth and development of children born following ICSI using sperm of different origins (ejaculated or non-ejaculated). For nonobstructive azoospermia (OA) patients, sperm derived from the testis may be more effective than derived from the epididymis. However, due to the limited sample size of the non-ejaculated group in this study, further investigations with larger sample sizes are needed to validate these findings.

Genetic Association in the Maintenance of the Mitochondrial Microenvironment and Sperm Capacity

Sperm motility is one of the major determinants of male fertility. Since sperm need a great deal of energy to support their fast movement by active metabolism, they are thus extremely vulnerable to oxidative damage by the reactive oxygen species (ROS) and other free radicals generated as byproducts in the electron transport chain. The present study is aimed at understanding the impact of a mitochondrial oxidizing/reducing microenvironment in the etiopathology of male infertility. We detected the mitochondrial DNA (mtDNA) 4,977 bp deletion in human sperm. We examined the gene mutation of ATP synthase 6 (ATPase6 m.T8993G) in ATP generation, the gene polymorphisms of uncoupling protein 2 (UCP2, G-866A) in the uncoupling of oxidative phosphorylation, the role of genes such as manganese superoxide dismutase (MnSOD, C47T) and catalase (CAT, C-262T) in the scavenging system in neutralizing reactive oxygen species, and the role of human 8-oxoguanine DNA glycosylase (hOGG1, C1245G) in 8-hydroxy-2′-deoxyguanosine (8-OHdG) repair. We found that the sperm with higher motility were found to have a higher mitochondrial membrane potential and mitochondrial bioenergetics. The genotype frequencies of UCP2 G-866A, MnSOD C47T, and CAT C-262T were found to be significantly different among the fertile subjects, the infertile subjects with more than 50% motility, and the infertile subjects with less than 50% motility. A higher prevalence of the mtDNA 4,977 bp deletion was found in the subjects with impaired sperm motility and fertility. Furthermore, we found that there were significant differences between the occurrences of the mtDNA 4,977 bp deletion and MnSOD (C47T) and hOGG1 (C1245G). In conclusion, the maintenance of the mitochondrial redox microenvironment and genome integrity is an important issue in sperm motility and fertility.

Testicular sperm extraction vs. ejaculated sperm use for nonazoospermic male factor infertility

OBJECTIVE

To study the potential benefit of testicular sperm compared with ejaculated sperm for men with oligospermia.

DESIGN

After exemption from institutional review board approval, we performed a retrospective cohort study using the Mayo Clinic Assisted Reproductive Technology database.

SETTING

Single academic center.

PATIENT(S)

Couples with nonazoospermic male factor infertility (total motile sperm <25 million per ejaculate) undergoing intracytoplasmic sperm injection with sperm obtained by testicular sperm extraction (TESE) or ejaculated sperm between 2016 and 2019.

INTERVENTION(S)

In vitro fertilization, Intracytoplasmic sperm injection, TESE.

MAIN OUTCOME MEASURE(S)

The primary outcome was live birth rate. The secondary outcomes were fertilization rate, blastulation rate, pregnancy rate, and miscarriage rate.

RESULT(S)

Subjects in the two groups were similar in age, body mass index, and ovarian reserve. Baseline sperm parameters were similar in the two groups: total motile sperm (5.4 in the ejaculate sperm group vs. 3.6 million motile per ejaculate), except that baseline motility was higher in the group that used ejaculated sperm (40% vs. 29%). The total number of mature oocytes retrieved was similar in the two groups, but the use of TESE was associated with a 20% decrease in fertilization (60.0% vs. 80.6%) and half the number of blastocyst embryos (two vs. four) compared with ejaculated sperm. Compared with ejaculated sperm, use of TESE did not improve the miscarriage rate (11% vs. 9%) or the live birth rate (50.0% vs. 31.3%).

CONCLUSION(S)

Patients with male factor infertility and oligozoospermia did not have improved ICSI outcomes with the use of TESE samples compared with ejaculated sperm.

TESE-ICSI outcomes per couple in vasectomized males are negatively affected by time since the intervention, but not other comorbidities

RESEARCH QUESTION

Does time since vasectomy (as obstructive interval) and the presence of different male comorbidities adversely affect the likelihood of achieving a newborn for vasectomized males undergoing testicular sperm extraction (TESE) and intracytoplasmic sperm injection (ICSI)?

DESIGN

This retrospective study included 364 couples with vasectomized males undergoing TESE-ICSI cycles with autologous oocytes at IVI Valencia. The main outcome was live birth rate (LBR). Subjects were divided according to the male risk factor evaluated into quartiles (obstructive interval, body mass index [BMI]) or groups (hypertension, diabetes mellitus, dyslipidaemia). The reproductive outcomes were calculated per embryo transfer, per ovarian stimulation completed, and per couple.

RESULTS

The average obstructive interval was 11.3 years. The LBR was 34.4% (95% CI 30.1-38.6) per embryo transfer, 27.8% (95% CI 24.1-31.5) per ovarian stimulation and 46.2% (95% CI 41.8-51.3) per couple. When considering obstructive interval, a significantly lower LBR per couple (P = 0.04) was found in the group with the longest obstruction time: Q1 42.1% (95% CI 33.5-50.7), Q2 49.1% (95% CI 36.1-62.1), Q3 56.3% (95% CI 46.7-65.9) and Q4 37.2% (95% CI 26.5-47.9) but the cumulative live birth rate (CLBR) was not affected (P = 0.63). LBR per ovarian stimulation of males with hypertension was significantly lower (P = 0.04) than healthy males: 13.5% (95% CI 2.5-24.5) and 28.6% (95% CI 24.7-32.5), respectively. The group of diabetic vasectomized males had a significantly higher CLBR (P = 0.02). The remaining risk factors assessed (smoking, dyslipidaemia and a high BMI) did not affect LBR compared with their healthy counterparts.

CONCLUSION

Time since vasectomy appears to negatively influence the LBR when assessed per couple. The CLBR was not affected by the obstructive interval or the presence of other male comorbidities apart from diabetes, which had a significant effect.

A comparison of the relative efficiency of ICSI and extended culture with epididymal sperm versus testicular sperm in patients with obstructive azoospermia

This is a retrospective cohort study comparing blastocyst transfer outcomes following intracytoplasmic sperm injection utilizing epididymal versus testicular sperm for men with obstructive azoospermia. All cases at a single center between 2012 and 2016 were included. Operative approach was selected at the surgeon's discretion and included microepididymal sperm aspiration or testicular sperm extraction. Blastocyst culture was exclusively utilized prior to transfer. The primary outcome was live birth rate. Secondary outcomes included fertilization rate, blastulation rate, euploidy rate, and implantation rate. A mixed effects model was performed. Seventy-six microepididymal sperm aspiration cases and 93 testicular sperm extraction cases were analyzed. The live birth rate was equivalent (48.6% vs 50.5%, P = 0.77). However, on mixed effects model, epididymal sperm resulted in a greater likelihood of fertilization (adjusted OR: 1.37, 95% CI: 1.05–1.81, P = 0.02) and produced a higher blastulation rate (adjusted OR: 1.41, 95% CI: 1.1–1.85, P = 0.01). As a result, the epididymal sperm group had more supernumerary blastocysts available (4.3 vs 3, P < 0.05). The euploidy rate was no different. Pregnancy rates were no different through the first transfer cycle. However, intracytoplasmic sperm injection following microepididymal sperm aspiration resulted in a greater number of usable blastocysts per patient. Thus, the true benefit of epididymal sperm may only be demonstrated via a comparison of cumulative pregnancy rates after multiple transfers from one cohort.

Sperm DNA fragmentation testing: Summary evidence and clinical practice recommendations

We herein summarise the evidence concerning the impact of sperm DNA fragmentation in various clinical infertility scenarios and the advances on sperm DNA fragmentation tests. The collected evidence was used to formulate 41 recommendations. Of these, 13 recommendations concern technical aspects of sperm DNA fragmentation testing, including pre‐analytical information, clinical thresholds and interpretation of results. The remaining 28 recommendations relate to indications for sperm DNA fragmentation testing and clinical management. Clinical scenarios like varicocele, unexplained infertility, idiopathic infertility, recurrent pregnancy loss, intrauterine insemination, in vitro fertilisation/intracytoplasmic sperm injection, fertility counselling for men with infertility risk factors and sperm cryopreservation have been contemplated. The bulk evidence supporting the recommendations has increased in recent years, but it is still of moderate to low quality. This guideline provides clinicians with advice on best practices in sperm DNA fragmentation testing. Also, recommendations are provided on possible management strategies to overcome infertility related to sperm DNA fragmentation, based on the best available evidence. Lastly, we identified gaps in knowledge and opportunities for research and elaborated a list of recommendations to stimulate further investigation.

Extended indications for sperm retrieval: summary of current literature

Sperm retrieval combined with intracytoplasmic sperm injection (ICSI) is the treatment of choice for couples with untreatable azoospermia-related infertility. However, an increasing body of evidence has been mounting, suggesting that ICSI with testicular sperm instead of ejaculated sperm (when both are available) increases pregnancy outcomes in some specific scenarios. This has led to the exploration of extended indications for sperm retrieval. This review summarizes the current literature concerning sperm retrieval and ICSI for non-azoospermic men with elevated sperm DNA fragmentation, oligozoospermia, and cryptozoospermia.

Testicular versus percutaneous epididymal sperm aspiration for patients with obstructive azoospermia: a systematic review and meta-analysis

Background

Intracytoplasmic sperm injection (ICSI) is a popular treatment for male infertility due to obstructive azoospermia (OA). Testicular sperm aspiration (TESA) and percutaneous epididymal sperm aspiration (PESA) are two common sperm retrieval approaches for ICSI among men with OA. However, the comparative efficacies of TESA and PESA have been debated for more than a decade and there has been no synthesis of the available evidence. This meta-analysis compared fertility outcomes between TESA and PESA among men with OA undergoing ICSI.

Methods

We searched Embase, PubMed, ScienceDirect, and Web of Science to identify studies comparing the effectiveness of TESA and PESA for ICSI. Study quality was assessed using the Newcastle-Ottawa scale. Data were pooled using a random-effects model. Outcomes were fertilization rate, implantation rate, pregnancy rate, and miscarriage rate. Results are expressed as odds ratio (OR) with 95% confidence intervals (CIs). Study heterogeneity was evaluated by the I-square (I²) statistic.

Results

Of 2,965 references retrieved, eight studies met eligibility criteria. These studies included 2,020 men receiving 2,060 ICSI cycles. The pooled results showed no significant differences in pregnancy and miscarriage rates between TESA and PESA groups, but TESA yielded a significantly higher implantation rate than PESA (OR =1.58, P=0.02, I²=24%).

Conclusions

TESA and PESA yielded similar pregnancy and miscarriage rates for couples receiving ICSI because of OA, but each demonstrated unique advantages and disadvantages. Further studies are required to evaluate safety outcomes and efficacy for specific clinical groups.

Interventions to Prevent Sperm DNA Damage Effects on Reproduction

Excessive oxidation and antioxidant imbalance resulting from several conditions may cause sperm DNA damage, which, in turn, affect male fertility, both natural and assisted. Sperm DNA damage transferred to the embryo might also affect the health of offspring. Several conditions associated with excessive oxidative stress are modifiable by the use of specific treatments, lifestyle changes, and averting exposure to environmental/occupational toxicants. Here, we discuss the strategies to reduce sperm DNA damage with a focus on clinical and surgical interventions.

Comparison of large-scale deletions of the sperm mitochondrial DNA in normozoospermic and asthenoteratozoospermic men

BACKGROUND AND OBJECTIVE

Mitochondria play a crucial role in energy metabolism for the survival and motility of sperm during fertilization. The aim of this study was to determine the association of large-scale mitochondrial DNA deletions with abnormal sperm motility and morphology in asthenoteratozoospermic patients.

MATERIALS AND METHODS

In this case-control study, 41 semen samples were collected from 18 normozoospermic healthy men and 23 asthenoteratozoospermic patients, according to the WHO guidelines. The swim-up technique was used for separation of spermatozoa on the basis of their motility. Long-range polymerase chain reaction (PCR) was used for screening of mitochondrial DNA (mtDNA) large-scale deletions, and primer shift PCR was used for confirmation of deletions.

RESULTS

The mean sperm motility, normal morphology, and progressive motility in asthenoteratozoospermic patients were significantly lower than in the normozoospermic group (P < 0.0001). There was a positive significant correlation between motility and normal sperm morphology ( P < 0.0001, r = 0.741). The results of long-range PCR revealed the existence of 4866-bp deletion along with the two common 4977-bp and 7436-bp deleted mtDNA in both groups. However, the frequency of multiple mtDNA deletions in the asthenoteratozoospermic group (15/23, 65.22%) was significantly higher than that in the normozoospermic group (7/18, 38.89%). Direct sequencing of the 534-bp PCR product revealed that it was amplified from the mtDNA with a 4866-bp deletion flanked by a seven-nucleotide direct repeat (5'-ACCCCCT-3').

CONCLUSIONS

Our findings suggested that these large-scale deletions of mtDNA may be genetic risk factors for poor sperm quality in asthenoteratozoospermia-induced male infertility. Thus, it is necessary to understand the mechanisms behind the generation of these deletions.

Testicular spermatozoon is superior to ejaculated spermatozoon for intracytoplasmic sperm injection to achieve pregnancy in infertile males with high sperm DNA damage

The purpose of this study was to compare the clinical outcome of testicular spermatozoon versus ejaculated spermatozoon in the treatment of infertile males with high sperm DNA damage, referred as sperm DNA fragmentation index (DFI), that attending intracytoplasmic sperm injection (ICSI) programme in terms of clinical pregnancy, births delivered as the primary and pregnancy loss and embryo fertilisation as the secondary outcome. A total of 102 males fulfilling the inclusion criteria were enrolled in the present study. Of the 102 males, 61 infertile males underwent testicular spermatozoon combined with ICSI while the remaining 41 males applied ejaculated spermatozoa in their first ICSI cycles, and the data of them were collected and analysed. In a 18-month follow-up, testicular spermatozoon achieved higher pregnancy rate and deliver rate than those in ejaculated sperm group (pregnancy rate, 36% vs. 14.6%, p = 0.017; deliver rate, 38.5% vs. 9.8%, p = 0.001). Nevertheless, there were no significant differences in the number of oocytes aspirated and number of embryos transferred between the two groups. Additionally, the fertilisation rate in the testicular sperm study cohort (70.4%) was also similar to that in the ejaculated sperm group (75.0%). Based on the current data, we conclude that testicular spermatozoon is the prior option in the treatment of infertile males with high sperm DFI in ICSI programme. More high-quality studies with larger samples size are needed in the future due to the relative small size and the nonrandomized design of the present study.

Human mitochondrial DNA haplogroup M8a influences the penetrance of m.8684C>T in Han Chinese men with non-obstructive azoospermia

RESEARCH QUESTION

What is the role of mitochondrial DNA (mtDNA) in the pathogenesis of non-obstructive azoospermia (NOA)?

DESIGN

mtDNA genome sequencing followed by an independent population validation were performed in 628 NOA cases and 584 healthy controls. Antioxidant capacity of serum was evaluated in 54 randomly selected cases out of 536 and 49 out of 489 controls.

RESULTS

In the screening stage, 13 mtDNA haplogroups (hg) were ascertained, and 10 susceptible variants were observed. In the validation stage, hg M8* in individuals was found to be associated with increased risk of NOA [odds ratio (OR) 2.61, 95% confidence interval (CI) 1.47-4.61] (P=0.001). Unexpectedly, the frequency of m.8684C>T, the defining marker for hg M8a, was also higher in NOA (OR 4.14, 95% CI 1.56-11.03) (P=0.002). Subsequently, the frequency distributions were compared among the sub-hg of hg M8* (including hg M8a, C and Z) and, intriguingly, no significance was found in hg C and Z. Additionally, the level of total antioxidant capacity was significantly decreased (P<0.05) compared with the control group.

CONCLUSIONS

hg M8a background in general played an active role in the penetrance of 8684C>T in NOA, and mtDNA genetic variants (causing low antioxidant levels) might increase mtDNA damage and impair normal spermatogenesis.

Superior clinical pregnancy rates after microsurgical epididymal sperm aspiration

Purpose

To assess normal fertilization, clinical pregnancy, and live birth rates after the use of microscopic epididymal sperm aspiration (MESA).

Methods

One-hundred-and-sixty azoospermic participants who underwent MESA were evaluated. The MESA was performed by using a micropuncture method with a micropipette. In cases in which motile sperm were not obtained after the MESA, conventional or micro-testicular sperm extraction (TESE) was completed.

Results

Adequate motile sperm were retrieved in 71 participants by using MESA and in 59 out of 89 participants by using TESE. Of the total number of patients, 123 underwent intracytoplasmic sperm injection. After MESA, the normal fertilization rate was 73.5% and the clinical pregnancy rate per case was 95.7%. Healthy deliveries resulted after MESA in 65 (92.9%) cases and after TESE in 38 (71.7%) cases.

Conclusion

The MESA specimen collection does not have any special requirements, such as mincing tissue disposition. The MESA also can reduce the amount of laboratory work that is needed for cryopreservation. In the authors' experience, MESA is a beneficial procedure and should be given priority over TESE.

Reproductive outcomes of testicular versus ejaculated sperm for intracytoplasmic sperm injection among men with high levels of DNA fragmentation in semen: systematic review and meta-analysis

OBJECTIVE

To compare sperm DNA fragmentation (SDF) levels between testicular and ejaculated sperm and to evaluate outcomes of intracytoplasmic sperm injection (ICSI) with the use of testicular (Testi-ICSI) versus ejaculated (Ejac-ICSI) sperm in nonazoospermic men with high SDF.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Normo- and oligozoospermic men with high levels of SDF in semen subjected to Testi-ICSI or Ejac-ICSI.

INTERVENTION(S)

Summary mean difference (MD) and odds ratio (OR) were calculated with the use of an inverse variance model and fixed- or random-effects models, respectively.

MAIN OUTCOME MEASURE(S)

Primary outcomes were SDF levels, clinical pregnancy rates (CPRs), and live birth rates (LBRs). Secondary outcomes were fertilization and miscarriage rates.

RESULT(S)

Five studies involving 143 patients provided paired SDF rates for testicular and ejaculated sperm, revealing lower SDF in testicular sperm (MD -24.58%). Four studies involving 507 cycles and 3,840 oocytes reported clinical outcomes of Testi-ICSI and Ejac-ICSI. Fertilization rates were not different between sperm sources, but a trend to lower rates was observed with Testi-ICSI. CPRs were higher for Testi-ICSI than for Ejac-ICSI, as were LBRs, whereas miscarriage rates were reduced with Testi-ICSI.

CONCLUSION(S)

Testicular sperm have lower levels of SDF than ejaculated sperm, with Testi-ICSI for high post-testicular SDF men improving reproductive outcomes compared with Ejac-ICSI. Infertile couples may benefit from Testi-ICSI if male partners have confirmed high SDF in the ejaculate.

Comparison of the Clinical Outcomes of Intracytoplasmic Sperm Injection Between Spermatozoa Retrieved From Testicular Biopsy and From Ejaculate in Cryptozoospermia Patients

OBJECTIVE

To compare the clinical outcomes of intracytoplasmic sperm injection (ICSI) between spermatozoa retrieved from testicular biopsy and from ejaculate in cryptozoospermia patients.

MATERIALS AND METHODS

The clinical data of 285 cryptozoospermia patients who underwent ICSI treatment in our center during the period from March 2009 to November 2013 were retrospectively analyzed. Within them, ejaculated sperms were used in 214 cases (group 1), and testicular sperms extracted by testicular sperm aspiration or conventional testis dissection sperm extraction were used in 71 cases (group 2). Good-quality embryo, fertilization, embryo implantation, pregnancy, and birth rates after ICSI were compared between the 2 groups.

RESULTS

Comparing the ejaculated sperm group with the testicular sperm group, fertilization rates were 59.6% and 60.6%, good-quality embryo rates were 36.8% and 46.1%, embryo implantation rates were 30.7% and 52.1%, pregnancy rates were 33.3% and 53.6%, and birth rates were 27.1% and 44.6%, respectively.

CONCLUSION

Using testicular sperms can achieve higher rates of embryo implantation, pregnancy, and birth compared with those using ejaculated sperms for ICSI treatment in cryptozoospermia patients.

Genetics and male infertility

The goal of this review is to explain the requirement for understanding the genetic structure of infertility arising from male factor and to discuss the essentials of these genetic elements (2). The majority of the population is affected by this disorder caused by male factor infertility (1); but the etiologies are still unknown. After the primary genetic structure in infertile phenotypes is searched, an evaluation can be made. Thus the reasons causing infertility can be discovered and patients can benefit from effective therapies (1). Publications about male infertility within the recent 10 years in the Pubmed database were discussed (1). There are some approachments for describing the function of specific genes, but no adequate study is present to be useful for diagnosing and treating male infertility (1). Male fertility and fertility in offspring of males are considerably affected by the exact transition of epigenetic information (1). When the genetic factors playing a role in male infertility were analysed, significant steps will be taken for treating patients and determining the reasons of idiopathic infertility (1). Developments in technology associated with the impact of genetics may enable to specify the etiology of male infertility by determining specific infertile phenotype marks (1).

A novel m.6307A>G mutation in the mitochondrial COXI gene in asthenozoospermic infertile men

Infertility affects 10-15% of the population, of which approximately 40% is due to male etiology and consists primarily of low sperm count (oligozoospermia) and/or abnormal sperm motility (asthenozoospermia). Recently, it has been demonstrated that mtDNA substitutions can influence semen quality. In this study, we performed a sequence analysis of the mitochondrial cytochrome oxidase I (COXI) gene in 31 infertile men suffering from asthenozoospermia in comparison to 33 normozoospermic infertile men and 100 fertile men from the Tunisian population. A novel m.6307A>G mutation was found in sperm mitochondrial DNA (mtDNA). This mutation was found in six asthenozoospermic patients, and was absent in normozoospermic and fertile men. We also detected 21 known substitutions previously reported in the Human Mitochondrial Database. The m.6307A>G mutation substitutes a highly conserved asparagine at position 135 to serine. In addition, PolyPhen-2 analysis predicted that this variant is "probably damaging.

Predictive factors for sperm retrieval and sperm injection outcomes in obstructive azoospermia: do etiology, retrieval techniques and gamete source play a role?

Obstructive azoospermia is a relatively common male infertility condition. The main etiologies of obstructive azoospermia include congenital, surgical-derived, traumatic and post-infectious cases. Although seminal tract reconstruction is a cost-effective treatment in most cases, this approach may not be feasible or desired in some cases. In such cases, assisted reproduction techniques offer a method for achieving pregnancy, notably via sperm retrieval and intracytoplasmic sperm injection. This process requires several considerations and decisions to be made, including the cause and duration of obstruction, which sperm retrieval technique to use, and whether to use fresh or frozen-thawed sperm. We present a review of obstructive azoospermia and assisted reproduction techniques, highlighting the most relevant aspects of the decision-making process for use in clinical practice.

Use of diagnostic testing to detect infertility

The evaluation of the infertile male continues to be a clinical challenge of increasing significance with considerable emotional and financial burdens. Many physiological, environmental and genetic factors are implicated; however, the etiology of suboptimal semen quality is poorly understood. This review focuses on the diagnostic testing currently available, as well as future directions that will be helpful for the practicing urologist and other clinicians to fully evaluate the infertile male.

Spermatogenesis affects the outcome of ICSI for azoospermic patients rather than sperm retrieval method

The study investigated the clinical outcome of intracytoplasmic sperm injection (ICSI) with epididymal and testicular sperm of azoospermic patients exhibiting various disturbances in spermatogenesis, in order to understand the possible factors that might affect ICSI outcome. Of the 134 patients, 92 were diagnosed as being obstructive azoospermic (OA group) with normal spermatogenesis and the remaining 42 patients were diagnosed as being non-obstructive azoospermic (NOA group) with hypospermatogenesis. The 92 OA patients underwent 112 ICSI cycles, which were divided into two subgroups according to their sperm retrieval methods: 1) OA-PESA group (n=51) with sperm obtained by percutaneous sperm aspiration (PESA) cycles and 2) OA-TEFNA group (n=61) with sperm obtained by testicular fine needle sperm aspiration (TEFNA) cycles. The NOA patients diagnosed with hypospermatogenesis according to histopathological analysis and hormone analysis, underwent 42 ICSI cycles with TEFNA. The results showed that the fertilization, cleavage, and clinical pregnancy rates portrayed a significant difference (44.9% vs. 64.1%, P<0.001, 79.8% vs. 89.0%, P<0.001, and 21.4% vs. 40.2%, P=0.047, respectively) between NOA and OA groups. Moreover, the miscarriage rate in the NOA group was visibly higher even though it did not reach a statistical difference (33.3% vs. 15.6%, P=0.433) compared with the miscarriage rate of the OA group. The same statistical differences were observed between the subgroup OA-TEFNA and the NOA group. No statistical difference was observed between OA-PESA and OA-TEFNA groups for the fertilization, cleavage, clinical pregnancy, and miscarriage rates. This study indicates that defective spermatogenesis affects the ICSI clinical outcome of azoospermic patients rather than the sperm retrieval methods.

Cannabinoid receptor 1 influences chromatin remodeling in mouse spermatids by affecting content of transition protein 2 mRNA and histone displacement

Marijuana smokers and animals treated with Δ9-tetrahydrocannabinol, the principal component of marijuana, show alterations of sperm morphology suggesting a role for cannabinoids in sperm differentiation and/or maturation. Because the cannabinoid receptor 1 (CNR1) activation appears to play a pivotal role in spermiogenesis, the developmental stage where DNA is remodeled, we hypothesized that CNR1 receptors might also influence chromatin quality in sperm. We used Cnr1 null mutant (Cnr1-/-) mice to study the possible role of endocannabinoids on sperm chromatin during spermiogenesis. We demonstrated that CNR1 activation regulated chromatin remodeling of spermatids by either increasing Tnp2 levels or enhancing histone displacement. Comparative analysis of wild-type, Cnr1+/-, and Cnr1-/- animals suggested the possible occurrence of haploinsufficiency for Tnp2 turnover control by CNR1, whereas histone displacement was disrupted to a lesser extent. Furthermore, flow cytometry analysis demonstrated that the genetic loss of Cnr1 decreased sperm chromatin quality and was associated with sperm DNA fragmentation. This damage increased during epididymal transit, from caput to cauda. Collectively, our results show that the expression/activity of CNR1 controls the physiological alterations of DNA packaging during spermiogenesis and epididymal transit. Given the deleterious effects of sperm DNA damage on male fertility, we suggest that the reproductive function of marijuana users may also be impaired by deregulation of the endogenous endocannabinoid system.

Assisted reproductive technology outcomes in azoospermic men: 10 years of experience with surgical sperm retrieval

An azoospermic man suffers from an absence of sperm in the ejaculate and this condition is present in about 10% of infertile men. Obstructive azoospermia (OA) is characterized by an occlusion or partial absence of the reproductive tract with the presence of normal spermatogenesis. On the other hand, non-obstructive azoospermia (NOA) is characterized by impaired spermatogenesis. In these cases, spermatozoa can be obtained by percutaneous epididymal or testicular sperm aspiration (PESA and TESA, respectively) and used for intracytoplasmic injection (ICSI). To compare ICSI outcomes using spermatozoa that were surgically retrieved by PESA and TESA, azoospermic patients were divided into the following categories: (i) TESA-NOA (n = 102), (ii) TESA-OA (n = 103), and (iii) PESA-OA (n = 171). Fertilization, pregnancy, and implantation rates were compared between the groups. We noted a lower normal fertilization rate (p = 0.0017) and a higher abortion rate (p = 0.0387) among men in the TESA group who had OA when compared with men in the PESA group who had OA. On the other hand, a lower normal fertilization rate (p = 0.05) and a lower rate of non-cleaved embryos (p = 0.034) was found in the TESA group of NOA patients as compared to the TESA group of OA patients. No statistically significant differences were detected between the TESA and PESA groups and the OA and NOA groups, respectively. The clinical outcomes of embryos arising from ICSI cycles using spermatozoa harvested via PESA and TESA were similar, regardless of whether the patient had obstructive or non-obstructive azoospermia.

Oxidative stress and male infertility--a clinical perspective

Oxidative stress occurs when the production of potentially destructive reactive oxygen species (ROS) exceeds the bodies own natural antioxidant defenses, resulting in cellular damage. Oxidative stress is a common pathology seen in approximately half of all infertile men. ROS, defined as including oxygen ions, free radicals and peroxides are generated by sperm and seminal leukocytes within semen and produce infertility by two key mechanisms. First, they damage the sperm membrane, decreasing sperm motility and its ability to fuse with the oocyte. Second, ROS can alter the sperm DNA, resulting in the passage of defective paternal DNA on to the conceptus. This review will provide an overview of oxidative biochemistry related to sperm health and will identify which men are most at risk of oxidative infertility. Finally, the review will outline methods available for diagnosing oxidative stress and the various treatments available.

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.

Distribution of the receptor for advanced glycation end products in the human male reproductive tract: prevalence in men with diabetes mellitus

BACKGROUND

Diabetics have a significantly higher percentage of sperm with nuclear DNA (nDNA) fragmentation and increased levels of advanced glycation end products (AGEs), in their testis, epididymis and sperm. As the receptor for AGEs (RAGE) is important to oxidative stress and cell dysfunction, we hypothesise, that it may be involved in sperm nDNA damage.

METHODS

Immunohistochemistry was performed to determine the presence of RAGE in the human testis and epididymis. A comparison of the receptor's incidence and localization on sperm from 10 diabetic and 11 non-diabetic men was conducted by blind semi-quantitative assessment of the immunostaining. Enzyme-linked immunosorbent assay analysis ascertained RAGE levels in seminal plasma and sperm from 21 diabetic and 31 non-diabetic subjects. Dual labelling immunolocalization was employed to evaluate RAGE's precise location on the sperm head.

RESULTS

RAGE was found throughout the testis, caput epididymis, particularly the principle cells apical region, and on sperm acrosomes. The number of sperm displaying RAGE and the overall protein amount found in sperm and seminal plasma were significantly higher in samples from diabetic men (P < 0.01, P < 0.0001 and P < 0.0001, respectively).

CONCLUSIONS

The presence of RAGE implies that it may play a central role in sperm nDNA damage particularly in diabetic men where the levels are elevated.

Sperm retrieval for obstructive azoospermia

Advances in the treatment of male infertility now routinely allow men with obstructive azoospermia to have fertility treatment without microsurgical reconstruction. A variety of methods for retrieving sperm from men with obstructive azoospermia have been described. The goals of sperm retrieval are to obtain the best quality sperm possible, to retrieve adequate numbers of sperm for immediate use and for cryopreservation, and to minimize damage to the reproductive tract.

Active digestion of sperm mitochondrial DNA in single living sperm revealed by optical tweezers

In almost all eukaryotes, mitochondrial (mt) genes are transmitted to progeny mainly from the maternal parent. The most popular explanation for this phenomenon is simple dilution of paternal mtDNA, because the paternal gametes (sperm) are much smaller than maternal gametes (egg) and contribute a limited amount of mitochondria to the progeny. Recently, this simple explanation has been challenged in several reports that describe the active digestion of sperm mtDNA, down-regulation of mtDNA replication in sperm, and proteolysis of mitochondria triggered by ubiquitination. In this investigation, we visualized mt nucleoids in living sperm by using highly sensitive SYBR green I vital staining. The ability to visualize mt nucleoids allowed us to clarify that the elimination of sperm mtDNA upon fertilization is achieved through two steps: (i) gradual decrease of mt nucleoid numbers during spermatogenesis and (ii) rapid digestion of sperm mtDNA just after fertilization. One notable point is that the digestion of mtDNA is achieved before the complete destruction of mitochondrial structures, which may be necessary to avoid the diffusion and transmission of potentially deleterious sperm mtDNA to the progeny.

Increase of ICSI efficiency with hyaluronic acid binding sperm for low aneuploidy frequency in pig

The present study was designed to evaluate the ability of hyaluronic acid binding sperm (HABS) in increasing the efficiency of intracytoplasmic sperm injection (ICSI) in terms of the production of chromosomally normal porcine embryos. Porcine embryos were produced by in vitro fertilization (IVF), ICSI and ICSI using hyaluronic acid binding sperm (ICSI-HABS). Chromosome aneuploidy in sperm and embryos was evaluated using chromosome 1 submetacentric probe for fluorescence in situ hybridization (FISH) analysis. No significant differences were observed in the blastocysts rates (18.6, 23.6 and 23.8%) and cell numbers (61.8+/-12.5, 55.5+/-7.3 and 59.3+/-9.6) among embryos derived from IVF, ICSI, and ICSI-HABS. However, the frequency of normal diploidy in ICSI-HABS (75.5%) was significantly higher (P<0.05) than that in IVF (57.0%) and ICSI (68.2%). Embryos from ICSI-HABS showed significantly lower chromosome abnormality rate (P<0.05). Both ICSI and IVF embryos showed higher rates of polyploidy, and hence chromosomally abnormal embryos, in comparison to ICSI-HABS embryos. In addition, we investigated the chromosomal complement of porcine spermatozoa by FISH. The rate of chromosome number abnormality in porcine sperm was found to be 6.25% (70/1120). Thus, we conclude that the use of hyaluronic acid binding sperm is superior to morphological sperm selection for ICSI in producing chromosomally normal embryos and increasing the ICSI efficiency by lowering the aneuploidy frequency. Our results indicate that the selection of normal sperm with hyaluronic acid binding assay might help to reduce the early embryonic mortality due to chromosomal aneuploidy thereby increasing the success rate of embryo transfer technology in pigs.

The impact of mitochondrial genetics on male infertility

Summary Human mitochondrial DNA (mtDNA) encodes 13 of the polypeptides associated with the process of oxidative phosphorylation (OXPHOS), the cells most important ATP generating pathway. Until recently, the effects of mtDNA rearrangements on male fertility have been largely ignored. However, it is becoming increasingly evident that both point mutations and large-scale deletions may have an impact on sperm motility and morphology. We discuss the implications of these rearrangements in the context of the clinical setting. We further discuss the possible consequences resulting from the transmission of sperm mtDNA deletions to the offspring. The role of nucleo-cytoplasmic interaction is investigated in the context of nuclear transcription and replication factors that regulate mtDNA transcription and replication.

A comparative study of oxidative DNA damage in mammalian spermatozoa

Alkaline gel electrophoresis, pulsed field gel electrophoresis, and quantitative PCR analyses (QPCR) of the nuclear (nDNA) and mitochondrial (mtDNA) genomes were used to assess DNA integrity in the spermatozoa of three species exposed to oxidative stress. In human and murine spermatozoa, the mtDNA was significantly more susceptible to H2O2-mediated damage than nDNA. In both eutherian species, exposure to 250 microM H2O2 induced around 0.6 lesions/10 kb of mtDNA. The mtDNA of human spermatozoa was particularly vulnerable to oxidative stress; 0.25, 1, and 5 mM H2O2 inducing DNA damage equivalent to 0.62, 1.34, and 1.42 lesions/10 kb, respectively. Such results emphasize the diagnostic significance of mtDNA as a biomarker of oxidative stress in the male germ line. In contrast, no damage could be detected by QPCR in the nDNA of either eutherian species, on exposure to H2O2 at doses as high as 5 mM. However, electrophoretic analysis indicated that severe oxidative stress could induce detectable nDNA fragmentation in human, but not murine spermatozoa. The mtDNA of tammar wallaby spermatozoa was relatively resistant to oxidative stress, only exhibiting damage (0.6 lesions/10 kb DNA) on exposure to 5 mM H2O2. By contrast, the nDNA of wallaby spermatozoa was significantly more susceptible to this oxidant than the other species. Such vulnerability is consistent with the lack of disulfide cross-linking in marsupial sperm chromatin and suggests that chromatin condensation during epididymal maturation may be important in establishing the resistance of these cells to the genotoxic effects of reactive oxygen species.

Sperm mitochondrial DNA depletion in men with asthenospermia

OBJECTIVE

To determine the content of sperm mitochondrial DNA (mtDNA) in patients with asthenospermia or with poor sperm motility.

DESIGN

Analysis of the content of mtDNA as the ratio between the amount of mtDNA and nuclear DNA by using a new concurrent polymerase chain reaction.

SETTING

University hospital infertility center.

PATIENT(S)

Eighty-six men who sought infertility therapy.

INTERVENTION(S)

Moving characteristics of sperm were examined with a computer-assisted semen analyzer.

MAIN OUTCOME MEASURE(S)

Sperm samples were classified into two groups, one with asthenospermia and the other with normal moving characteristics. The content of mtDNA in sperm was determined by polymerase chain reaction. We analyzed the mitochondrial mass by MitoTracker Green staining and analyzed DNA content with propidium iodide staining by flow cytometry.

RESULT(S)

A decrease in sperm mtDNA content was detected in patients with asthenospermia or with poor sperm motility (<20% motility). The relative mtDNA contents in the asthenospermia and normal groups were 7.2 +/- 1.3 (mean +/- SD, n = 23) and 74.1 +/- 2.0 (n = 29), respectively. Lower intensities of propidium iodide staining were detected in patients with asthenospermia or poor motility, but there was no significant difference in MitoTracker Green staining between the sperm with different motility.

CONCLUSION(S)

We suggest that mtDNA content may serve as a useful indicator of sperm quality and that mtDNA depletion may play an important role in the pathophysiology of some male infertility.

Differences in mitochondrial and nuclear DNA status of high-density and low-density sperm fractions after density centrifugation preparation

OBJECTIVE

To determine the mitochondrial DNA and nuclear DNA fragmentation of sperm populations separated by using discontinuous density gradient.

DESIGN

Analysis of mitochondrial and nuclear DNA status of sperm from high and low density layers.

SETTING

Regional fertility center.

PATIENT(S)

Twenty-eight men who presented for an initial infertility investigation.

MAIN OUTCOME MEASURE(S)

Semen was prepared by using discontinuous density gradient (90.0%:45.0%) and subjected to a modified long polymerase chain reaction to assess mitochondrial DNA deletions and to a modified single-cell alkaline gel electrophoresis assay to determine nuclear DNA fragmentation.

RESULT(S)

The high-density fraction displayed significantly more wild-type mitochondrial DNA (75% of samples) than did the low-density fraction (25% of samples). In the high-density fraction, the incidence of single deletions was higher than that of double or multiple deletions, and the deletions were predominantly small. A strong correlation was observed between nuclear DNA fragmentation and the number and size of mitochondrial DNA deletions.

CONCLUSION(S)

Density centrifugation isolates a population of sperm with high-quality mitochondrial DNA and nuclear DNA.

Importance of mitochondrial and nuclear sperm DNA in sperm quality assessment and assisted reproduction outcome

Intracytoplasmic sperm injection (ICSI) has made irrelevant the conventional criteria of concentration, motility and morphology for assessment of sperm quality and so we urgently need new assays by which to gauge sperm 'health'. ICSI may be facilitating the transfer of genetic disorders to future generations by bypassing all the natural hurdles for sperm selection without imposing more pertinent criteria of selection. Sperm DNA quality is vital to the future offspring irrespective of whether the child is conceived naturally, by in vitro fertilization (IVF) or by ICSI. The DNA integrity of sperm can be determined quickly and accurately using a range of techniques that also have strong prognostic power in predicting successful IVF and ICSI outcomes with ejaculated sperm. Moreover, there is a close correlation between testicular nuclear DNA integrity and pregnancy rates in ICSI. Mitochondrial DNA can be measured using long PCR in ejaculated and testicular sperm and is also useful for predicting success in assisted conception. This review discusses how the integrity of both nuclear and mitochondrial affect the choice of sperm for assisted conception.