Effectiveness of human spermatozoa biomarkers as indicators of structural damage during cryopreservation

Effect of Conditioned Medium from Human Adipose-Derived Mesenchymal Stem Cells on Human Sperm Quality During Cryopreservation

The cryopreservation procedure decreases sperm quality, causing certain changes at structural and molecular levels affecting fertilizing ability. We aimed to investigate the impacts of human adipose-derived mesenchymal stem cells (HAd-MSCs) conditioned medium (CM) on the protection of human sperm from cryoinjury. Thirty normal semen specimens were evaluated in this study. Each specimen was separated into six groups and enhanced with varying concentrations of human Ad-MSCs-CM (0, 10, 30, 50, 70, and 100%). Sperm motility, viability, morphology, apoptosis, mitochondrial potential, and lipid peroxidation, and DNA fragmentation were evaluated before freezing and after thawing. The results showed that the total motility was preserved in 10% human Ad-MSCs-CM group. Also, DNA fragmentation was significantly lower in 10% compared to 0% human Ad-MSCs-CM (63.62 ± 17.72% vs.76.46 ± 4.87%, respectively, P < 0.004). Human Ad-MSCs-CM in groups of 10, 30, 50, and 70% reduced lipid peroxidation. The normal sperm morphology rate, mitochondrial membrane potential, and apoptosis showed no significant differences across various groups. It seems that human Ad-MSCs-CM can protect the sperm parameters during the cryopreservation by decreasing cryoinjury.

Effects of Slow Freezing and Vitrification of Human Semen on Post-Thaw Semen Quality and miRNA Expression

Semen cryopreservation has played an important role in medically assisted reproduction for decades. In addition to preserving male fertility, it is sometimes used for overcoming logistical issues. Despite its proven clinical usability and safety, there is a lack of knowledge of how it affects spermatozoa at the molecular level, especially in terms of non-coding RNAs. Therefore, we conducted this study, where we compared slow freezing and vitrification of good- and poor-quality human semen samples by analyzing conventional sperm quality parameters, performing functional tests and analyzing the expression of miRNAs. The results revealed that cryopreservation of normozoospermic samples does not alter the maturity of spermatozoa (protamine staining, hyaluronan binding), although cryopreservation can increase sperm DNA fragmentation and lower motility. On a molecular level, we revealed that in both types of cryopreservation, miRNAs from spermatozoa are significantly overexpressed compared to those in the native semen of normozoospermic patients, but in oligozoospermic samples, this effect is observed only after vitrification. Moreover, we show that expression of selected miRNAs is mostly overexpressed in native oligozoospermic samples compared to normozoospermic samples. Conversely, when vitrified normozoospermic and oligozoospermic samples were compared, we determined that only miR-99b-5p was significantly overexpressed in oligozoospermic sperm samples, and when comparing slow freezing, only miR-15b-5p and miR-34b-3p were significantly under-expressed in oligozoospermic sperm samples. Therefore, our results imply that cryopreservation of normozoospermic sperm samples can modulate miRNA expression profiles in spermatozoa to become comparable to those in oligozoospermic samples.

A Pilot Analysis of Whole Transcriptome of Human Cryopreserved Sperm

Sperm cryopreservation is a procedure widely used to store gametes for later use, to preserve fertility in patients prior to gonadotoxic treatments or surgery, and for sperm donation programs. The purpose of the study was to assess the impact of cryopreservation on human sperm transcriptome. Semen samples were collected from 13 normospermic men. Each sample was divided into two aliquots. The total RNA was immediately extracted from one aliquot. The second aliquot was frozen and total RNA was extracted after a week of storage in liquid nitrogen. The RNA samples were randomized in four pools, each of six donors, and analyzed by microarrays. The paired Significance Analysis of Microarray was performed. We found 219 lower abundant transcripts and 28 higher abundant transcripts in cryopreserved sperm than fresh sperm. The gene ontology analysis disclosed that cryopreservation alters transcripts of pathways important for fertility (i.e., spermatogenesis, sperm motility, mitochondria function, fertilization, calcium homeostasis, cell differentiation, and early embryo development), although the increase of some transcripts involved in immune response can compensate for the harmful effects of freezing.

Cryopreservation Induces Acetylation of Metabolism-Related Proteins in Boar Sperm

Cryodamage affects the normal physiological functions and survivability of boar sperm during cryopreservation. Lysine acetylation is thought to be an important regulatory mechanism in sperm functions. However, little is known about protein acetylation and its effects on cryotolerance or cryodamage in boar sperm. In this study, the characterization and protein acetylation dynamics of boar sperm during cryopreservation were determined using liquid chromatography-mass spectrometry (LC-MS). A total of 1440 proteins were identified out of 4705 modified proteins, and 2764 quantifiable sites were elucidated. Among the differentially modified sites, 1252 were found to be upregulated compared to 172 downregulated sites in fresh and frozen sperms. Gene ontology indicated that these differentially modified proteins are involved in metabolic processes and catalytic and antioxidant activities, which are involved in pyruvate metabolism, phosphorylation and lysine degradation. In addition, the present study demonstrated that the mRNA and protein expressions of SIRT5, IDH2, MDH2 and LDHC, associated with sperm quality parameters, are downregulated after cryopreservation. In conclusion, cryopreservation induces the acetylation and deacetylation of energy metabolism-related proteins, which may contribute to the post-thawed boar sperm quality parameters.

The impact of cryopreserved sperm on intrauterine insemination outcomes: is frozen as good as fresh?

Introduction

Frozen sperm utilization might negatively impact cycle outcomes in animals, implicating cryopreservation-induced sperm damage. However, in vitro fertilization and intrauterine insemination (IUI) in human studies are inconclusive.

Methods

This study is a retrospective review of 5,335 IUI [± ovarian stimulation (OS)] cycles from a large academic fertility center. Cycles were stratified based on the utilization of frozen (FROZEN, n = 1,871) instead of fresh ejaculated sperm (FRESH, n = 3,464). Main outcomes included human chorionic gonadotropin (HCG) positivity, clinical pregnancy (CP), and spontaneous abortion (SAB) rates. Secondary outcome was live birth (LB) rate. Odds ratios (OR) for all outcomes were calculated utilizing logistic regression and adjusted (adjOR) for maternal age, day-3 FSH, and OS regimen. Stratified analysis was performed based on OS subtype [gonadotropins; oral medications (OM): clomiphene citrate and letrozole; and unstimulated/natural]. Time to pregnancy and cumulative pregnancy rates were also calculated. Further subanalyses were performed limited to either the first cycle only or to the partner's sperm only, after excluding female factor infertility, and after stratification by female age (<30, 30-35, and >35 years old).

Results

Overall, HCG positivity and CP were lower in the FROZEN compared to the FRESH group (12.2% vs. 15.6%, p < 0.001; 9.4% vs. 13.0%, p < 0.001, respectively), which persisted only among OM cycles after stratification (9.9% vs. 14.2% HCG positivity, p = 0.030; 8.1% vs. 11.8% CP, p = 0.041). Among all cycles, adjOR (95% CI) for HCG positivity and CP were 0.75 (0.56-1.02) and 0.77 (0.57-1.03), respectively, ref: FRESH. In OM cycles, adjOR (95% CI) for HCG positivity [0.55 (0.30-0.99)] and CP [0.49 (0.25-0.95), ref.: FRESH] favored the FRESH group but showed no differences among gonadotropin and natural cycles. SAB odds did not differ between groups among OM and natural cycles but were lower in the FROZEN group among gonadotropin cycles [adjOR (95% CI): 0.13 (0.02-0.98), ref.: FRESH]. There were no differences in CP and SAB in the performed subanalyses (limited to first cycles or partner's sperm only, after excluding female factors, or after stratification according to female age). Nevertheless, time to conception was slightly longer in the FROZEN compared to the FRESH group (3.84 vs. 2.58 cycles, p < 0.001). No significant differences were present in LB and cumulative pregnancy results, other than in the subgroup of natural cycles, where higher LB odds [adjOR (95% CI): 1.08 (1.05-1.12)] and higher cumulative pregnancy rate (34% vs. 15%, p = 0.002) were noted in the FROZEN compared to the FRESH group.

Conclusion

Overall, clinical outcomes did not differ significantly between frozen and fresh sperm IUI cycles, although specific subgroups might benefit from fresh sperm utilization.

Sperm Cryopreservation Today: Approaches, Efficiency, and Pitfalls

The cryopreservation of human spermatozoa has been an option for patients undergoing chemo or radiotherapies since the late 1950s. Presently, there are different techniques for the cryopreservation of spermatozoa. The most commonly used techniques are programmable slow freezing and freezing on liquid nitrogen vapors, while the use of vitrification is still not accepted as clinically relevant. Although there have been many improvements, the ideal technique for achieving better post-thaw sperm quality continues to be a mystery. A major obstacle during cryopreservation is the formation of intracellular ice crystals. Cryodamage generated by cryopreservation causes structural and molecular alterations in spermatozoa. Injuries can happen because of oxidative stress, temperature stress, and osmotic stress, which then result in changes in the plasma membrane fluidity, motility, viability, and DNA integrity of the spermatozoa. To prevent cryodamage as much as possible, cryoprotectants are added, and in some clinical trial cases, even antioxidants that may improve post-thaw sperm quality are added. This review discusses cryopreservation techniques, cryodamage on molecular and structural levels, and cryoprotectants. It provides a comparison of cryopreservation techniques and describes recent advances in those techniques.

Density Gradient Centrifugation Alone or the Combination of DGC with Annexin V Magnetic-Activated Cell Sorting Prior to Cryopreservation Enhances the Postthaw Quality of Sperm from Infertile Male Patients with Poor Sperm Quality

Objective. To examine whether density gradient centrifugation (DGC) alone or its combination with annexin V magnetic-activated cell sorting (DGC-MACS) can be used to process semen samples from infertile male patients with poor sperm quality prior to subjecting these to freeze/thaw process in order to optimize the outcomes of sperm freezing. Methods. This study enrolled sixteen patients with sperm $\text{concentration}\ge 20\times {10}^6/\text{mL}$ , sperm $\text{motility}<30$ %, and/or <4% normal sperm morphology. Sperms were processed by DGC or DGC-MACS prior to the freeze/thaw process. Sperm motility, hyperosmotic swelling test (HOS), TUNEL test, and morphological analysis were performed before and after the freeze/thaw process. Results. The freeze/thaw process had a detrimental effect on sperm motility, viability, morphology, and DNA integrity in all three groups (RAW, DGC, and DGC + MACS groups). The DGC and DGC + MACS groups showed increased sperm motility, viability, and normal morphology following freeze/thaw than untreated frozen controls. The motility and viability were not significantly different between DGC-MACS-CPT (cryopreservation-thawing) and DGC-CPT groups. Moreover, almost no grade A or grade B sperm was observed in the DGC-MACS-CPT groups. The sperm selected by DGC or DGC + MACS showed decreased levels of sperm DNA fragmentation than RAW samples following freeze/thaw. Moreover, the sperm DNA fragmentation following freeze/thaw in the DGC-MACS-CPT group was significantly lower than that in the DGC-CPT group. Conclusions. Sperm preparation by DGC before cryopreservation improved the quality of sperm postthaw in infertile males with poor sperm quality. If the sperm quality following freeze/thaw is foreseen to be insufficient for artificial insemination with husband’s sperm or in vitro fertilization, or if there is high DNA fragmentation in RAW sperm, DGC + MACS should be used prior to cryopreservation to reduce sperm DNA fragmentation and improve the quality of sperm available for intracytoplasmic sperm injection.

Cryopreservation of Human Spermatozoa: Functional, Molecular and Clinical Aspects

Cryopreservation is an expanding strategy to allow not only fertility preservation for individuals who need such procedures because of gonadotoxic treatments, active duty in dangerous occupations or social reasons and gamete donation for couples where conception is denied, but also for animal breeding and preservation of endangered animal species. Despite the improvement in semen cryopreservation techniques and the worldwide expansion of semen banks, damage to spermatozoa and the consequent impairment of its functions still remain unsolved problems, conditioning the choice of the technique in assisted reproduction procedures. Although many studies have attempted to find solutions to limit sperm damage following cryopreservation and identify possible markers of damage susceptibility, active research in this field is still required in order to optimize the process. Here, we review the available evidence regarding structural, molecular and functional damage occurring in cryopreserved human spermatozoa and the possible strategies to prevent it and optimize the procedures. Finally, we review the results on assisted reproduction technique (ARTs) outcomes following the use of cryopreserved spermatozoa.

Quercetin: Putative effects on the function of cryopreserved sperms in domestic animals

Quercetin is one of the most used antioxidant flavonoids and largely exists in many fruits and vegetables because of its capability to scavenge the free reactive oxygen species (ROSs) by repressing lipid peroxy radical fusion, metal ion chelating through enzyme inhibition, and adopting the repair mechanisms. It also exhibits various biological actions, including antioxidative, anti-inflammatory and antimicrobial activities. Furthermore, it contributes well to sustaining the endogenous cellular antioxidant defence system. The process of cryopreservation is associated with increased oxidative stress, and some steps are potential sources of ROSs, including the method of semen collection, handling, cryopreservation culture media, and thawing, which result in impaired sperm function. Several antioxidants have been proposed to counteract the harmful impact of ROS during semen cryopreservation. The antioxidant capability of quercetin has been verified in different animal species for providing valuable defence to sperm during the cryopreservation process. The beneficial properties of quercetin on various parameters of fresh and post-thaw sperm in different species are clarified in this review. More in-depth investigations are required to clarify quercetin's mechanism of action in different animal species.

Effect of platelet-rich plasma (PRP) on post-thaw quality, kinematics and in vivo fertility of fertile and subfertile buffalo (Bubalus bubalis) spermatozoa

This study investigated the effect of adding platelet-rich plasma (PRP) in semen extender prior cryopreservation on post-thaw quality, kinematics, and in vivo fertility of fertile and subfertile buffalo spermatozoa. Eleven buffalo bulls were classified based on their conception rate (CR) into fertile (n = 8, CR > 55%) and subfertile (n = 3, CR < 35%) groups. Ejaculates were collected with artificial vagina, pooled, and dispensed into 6 aliquots, diluted with Tris-egg yolk-glycerol extender supplemented with different proportions of PRP [0% (control), 5%, 10%, 15%, 20%, and 25%] followed by cryopreservation using standard procedures. Post-thaw sperm quality, kinematics, antioxidant activity, cryosurvival rate, and in vivo fertility were compared between fertile and subfertile groups and among proportions of PRP within each group. The results showed that 15% PRP greatly (P < 0.001) improved sperm characteristics, average path velocity, and curvilinear velocity of the subfertile group. Interestingly, 5%, 10%, and 15% PRP greatly (P < 0.001) reduced malondialdehyde content and improved enzymatic (glutathione peroxidase and superoxide dismutase) and total antioxidant capacity in fertile and subfertile groups. However, these three proportions of PRP significantly (P < 0.001) improved the cryosurvival rate of the subfertile group; only 15% PRP greatly improved CR of subfertile (60.83% vs. 34.17%) animals to be comparable with that of fertile ones treated with 5 (59.17%) and 10% (60.83%) PRP. In conclusion, adding 15% PRP to semen extender before cryopreservation is recommended to improve post-thaw quality, antioxidant activity, and in vivo fertility of buffalo semen particularly of the subfertile animals.

A Simple and Efficient Method to Cryopreserve Human Ejaculated and Testicular Spermatozoa in −80°C Freezer

Human autologous sperm freezing involves ejaculated sperm, and testicular or epididymal puncture sperm freezing, and autologous sperm freezing is widely used in assisted reproductive technology. In previous studies, researchers have tried to cryopreserve sperm from mammals (rats, dogs, etc.) using a −80°C freezer and have achieved success. It is common to use liquid nitrogen vapor rapid freezing to cryopreserve human autologous sperm. However, the operation of this cooling method is complicated, and the temperature drop is unstable. In this study, we compared the quality of human ejaculation and testicular sperm after liquid nitrogen vapor rapid freezing and −80°C freezing for the first time. By analyzing sperm quality parameters of 93 ejaculated sperm and 10 testicular sperm after liquid nitrogen vapor rapid freezing and −80°C freezing, we found reactive oxygen species (ROS) of sperm of the −80°C freezer was significantly lower than liquid nitrogen vapor rapid freezing. Regression analysis showed that progressive motility, ROS, and DNA fragmentation index (DFI) in post-thaw spermatozoa were correlated with sperm progressive motility, ROS, and DFI before freezing. For the freezing method, the −80°C freezer was positively correlated with the sperm progressive motility. Among the factors of freezing time, long-term freezing was negatively correlated with sperm progressive motility and ROS. Although freezing directly at −80°C freezer had a slower temperature drop than liquid nitrogen vapor rapid freezing over the same period, the curves of the temperature drop were similar, and slight differences in the freezing point were observed. Furthermore, there were no statistically significant differences between the two methods for freezing testicular sperm. The method of direct −80°C freezing could be considered a simplified alternative to vapor freezing for short-term human sperm storage. It could be used for cryopreservation of autologous sperm (especially testicular sperm) by in vitro fertilization centers.

Clinical Trial Registration: (website), identifier (ChiCTR2100050190).

Beneficial effects of hypotaurine supplementation in preparation and freezing media on human sperm cryo-capacitation and DNA quality

BACKGROUND

Although widely used, slow freezing considerably modifies the functions of human spermatozoa. Cryopreservation induces nuclear sperm alterations and cryo-capacitation, reducing the chances of pregnancy. Hypotaurine is naturally present in the male and female genital tracts and has capacitating, osmolytic and anti-oxidant properties. The analysis were performed on surplus semen of men with normal (n = 19) or abnormal (n = 14) sperm parameters. Spermatozoa were selected by density gradient centrifugation before slow freezing. For each sample, these steps were performed in parallel with ("H+" arm) or without ("H-" arm) hypotaurine supplementation. After thawing, we measured total and progressive mobility, vitality, acrosome integrity, markers of capacitation signaling pathway and nuclear quality. For the latter, we focused on sperm chromatin packaging, DNA fragmentation and the presence of vacuoles in the sperm nucleus.

RESULTS

Post-thaw spermatozoa selected and frozen in the presence of hypotaurine had a higher vitality (+ 16.7%, p < 0.001), progressive and total motility (+ 39.9% and +  21.6% respectively, p < 0.005) than spermatozoa from the control "H-" arm. Hypotaurine also reduced the non-specific phosphorylation of the capacitation protein markers P110 and P80 (p < 0.01), indicating a decrease in cryo-capacitation. Hypotaurine supplementation reduced chromatin decondensation, measured by chromomycin A3 (- 16.1%, p < 0.05), DNA fragmentation (- 18.7%, p < 0.05) and nuclear vacuolization (- 20.8%, p < 0.05).

CONCLUSION

Our study is the first to demonstrate beneficial effects of hypotaurine supplementation in preparation and freezing procedures on human spermatozoa sperm fertilization capacity and nucleus quality. Hypotaurine supplementation limited cryo-capacitation, increased the proportion of live and progressively motile spermatozoa and reduces the percentage of spermatozoa showing chromatin decondensation, DNA fragmentation and nuclear vacuolation.

TRIAL REGISTRATION

Clinical Trial, NCT04011813 . Registered 19 May 2019 - Retrospectively registered.

Fresh vs frozen testicular sperm for assisted reproductive technology in patients with non-obstructive azoospermia: A systematic review

Objective

: To review the debate about the routine use of cryopreserved testicular sperm for intracytoplasmic sperm injection (ICSI) from patients with non-obstructive azoospermia (NOA), as some authors suggest repeating sperm retrieval in such cases due to poorer ICSI results when frozen–thawed testicular sperm is used compared with fresh sperm.

Methods

: A systematic literature review was performed in August 2020 using the Medical Literature Analysis and Retrieval System Online (MEDLINE), Web of Science databases and the Excerpta Medica dataBASE (EMBASE), and we included 26 studies that were considered eligible for this systematic review.

Results

: In all, 1189 publications were screened and 26 articles were included in the systematic review. Three meta-analysis reviews were included and they all concluded that the use of fresh and frozen sperms for ICSI from patients with NOA showed comparable fertilisation and pregnancy rates.

Conclusion

: The use of frozen testicular sperm from men with NOA results in fertilisation and clinical pregnancy rates similar to those of fresh sperm. This may encourage fertility centres to use frozen testicular sperm samples, as this policy has certain advantages that would help with organising their workflow.

Abbreviations: CPR: clinical pregnancy rate; 2PN%: two pronuclei % fertilisation rate; ICSI: intracytoplasmic sperm injection; NOA: non-obstructive azoospermia; OA, obstructive azoospermia; SCO: Sertoli cell-only syndrome; (micro-)TESE: (microsurgical) testicular sperm extraction

Fertility and flow cytometry evaluations of ram frozen semen in plant-based extender supplemented with Mito-TEMPO

Semen cryopreservation is an effective strategy for distributing spermatozoa for artificial insemination, but this process reduces the fertility potential of post-thawed spermatozoa. The current study was conducted to assess effects of the novel mitochondria-targeted antioxidant "Mito-TEMPO" on ram sperm quality and fertility potential during the freeze-thawing process in a plant-based extender. Semen samples were diluted in extenders supplemented with 0, 0.5, 5, 50 and 500 µM Mito-TEMPO and then frozen using a standard protocol. Motility, abnormal morphology, acrosome integrity, membrane integrity, mitochondria membrane potential, viability, apoptotic-like changes, lipid peroxidation, DNA fragmentation, H2O2 concentration and fertility potential were assessed after thawing. Results indicated that with the 5 and 50 μM Mito-TEMPO there was a greater (P ≤ 0.05) percentage of sperm total motility, progressive motility, acrosome integrity and viability as well as less (P ≤ 0.05) lipid peroxidation and late apoptotic-like changes. Membrane integrity and mitochondria membrane potential were greater (P ≤ 0.05) with the 50 μM Mito-TEMPO extender supplementation. Furthermore, with 0.5, 5 and 50 μM Mito-TEMPO supplementations there was a greater (P ≤ 0.05) average path velocity and lesser (P ≤ 0.05) percentages of spermatozoa with DNA fragmentation and relatively greater H2O2 concentration. Results from the fertility experiment indicated the 5 and 50 μM Mito-TEMPO treatments resulted in greater pregnancy, parturition and lambing rates. It, therefore, is concluded that Mito-TEMPO may enhance quality and fertility potential of post-thawed semen of rams.

Sperm Response to in vitro Stress Conditions in Wild and Domestic Species Measured by Functional Variables and ROS Production

The domestication process has resulted in profound changes in the reproductive physiology of the animals that might have affected the sperm characteristics and thus their sensitivity to handling and cryopreservation procedures. This work assesses the response of the sperm of domestic and wild ungulates to a cooling storage at 15°C for 20 h followed by incubation at 38.5°C, 5% CO₂, for 2 h. In addition, this paper examines the most representative sperm traits to assess their responsiveness to these stress conditions. Sperm samples were collected from domestic and their wild ancestor species: ram, mouflon, buck, Iberian ibex, domestic boar, and wild boar. Sperm motility, viability, mitochondrial membrane status, DNA fragmentation, and reactive oxygen species production were evaluated at the beginning of the experiment, after 20 h of refrigeration at 15°C, and, finally, at 2 h of incubation at 38.5°C. Sperm from all domestic species (ram, buck, and domestic boar) suffered more stress than their wild relatives (mouflon, Iberian Ibex, and wild boar). In pigs, the percentage of intact mitochondria was lower in the domestic species compared to wild boar. In sheep, we found a higher reactive oxygen species production in rams, while in goats, the curvilinear velocity was lower in the domestic species. The PCA (principal components analysis) showed that the motility and their kinetic variables were the most represented variables in the principal components of all species, indicating that they are essential biomarkers for evaluating the stress response. Sperm viability was highlighted as a representative variable for evaluating the stress response in domestic boar, mouflon, ram, and ibex.

The impact of fresh and frozen testicular tissue quality on embryological and clinical outcomes

Our ability to predict the potential of testicular spermatozoa to support embryonic development is still limited. Although motility of testicular spermatozoa is associated with embryo development, the impact of morphology and the presence of spermatozoa in the testicular sample has not been previously researched. Moreover, while the majority of data indicate no effect of cryopreservation, there are studies reporting impaired clinical outcomes due to testicular cryopreservation. In a retrospective study, 118 ICSI-TESE cycles were analysed to study the impact of (a) total quality of testicular tissue, (b) testicular tissue cryopreservation and (c) presence/motility/morphology of testicular spermatozoa in fertilisation rate, embryonic development, clinical pregnancy (CPR), ongoing pregnancy (OPR) and live birth rate (LBR). Results showed that fertilisation rate was significantly affected by both total quality of testicular tissue (p < .05) and rare presence of spermatozoa (p < .01). Moreover, total tissue quality (p < .01), cryopreservation of low-quality samples (p < .01), absence of motile testicular spermatozoa (p < .01) and poor spermatozoa morphology (p < .05) had a negative impact on the number of good quality day 3 embryos. CPR, OPR or LBR was not affected by any parameters examined. Our data suggest that the quality of testicular tissue influences both fertilisation rate and embryo development. Moreover, cryopreservation of low-quality testicular samples has a negative impact on the number of available embryos for transfer.

Effect of autologous platelet-rich plasma on human sperm quality during cryopreservation

As a source of growth factors, platelet-rich plasma (PRP) has been widely used in the repair of various injuries due to its cytoprotective properties in regenerative medicine. The objective of the present study was to investigate the effect of autologous PRP supplementation on the quality of frozen-thawed human sperm. Twelve normozoospermic semen samples were collected, and each sample was divided into 4 aliquots and added with different proportions of PRP (0%, 2%, 5%, and 10%) separately, followed by cryopreservation. Sperm motility, viability, membrane integrity, DNA fragmentation index (DFI), reactive oxygen species (ROS) levels and mitochondrial membrane potential were measured and analyzed. The results showed that the addition of 5% PRP improved sperm progressive motility (30.3 ± 2.7 VS. 28.1 ± 2.6), viability (65.5 ± 4.2 VS. 59.6 ± 3.9), and membrane integrity (52.4 ± 3.6 VS. 49.2 ± 3.4) after cryopreservation (P < 0.05). Slight attenuation of ROS generation, restoration of mitochondrial membrane potential and reduction of DNA fragments were also observed in post-thawed sperm supplemented with PRP, but there was no significant (P > 0.05). In conclusion, autologous PRP has a partial protective effect on cryopreservation of human spermatozoa, and the combined application with other high-efficiency cryoprotectant is worthy of further study.

Improving native human sperm freezing protection by using a modified vitrification method

Slow freezing is the most commonly used technique for the cryopreservation of spermatozoa in clinical practice. However, it has been shown to have a negative impact on sperm function and structure. Vitrification as a successful alternative method has been proved to have better protective effects on human embryos, but vitrification of spermatozoa is still subject to low recovery rates. In this study, a modified vitrification method for native spermatozoa was developed. A total of 28 semen samples were included; each sample was divided into three equal parts and assigned to fresh, slow freezing, and vitrification groups. Sperm vitality, motility, morphology, DNA integrity, and acrosome reaction were assessed for each of the groups. The results showed that vitrification achieves better results for several sperm protection parameters than slow freezing; vitrification achieves a higher recovery rate (P < 0.05), motility (P < 0.05), morphology (P < 0.05), and curve line velocity (P < 0.05) than slow freezing. Furthermore, DNA fragmentation was decreased (P < 0.05) and better acrosome protection (P < 0.05) was exhibited in the spermatozoa after vitrification. Principal component analysis of all sperm parameters revealed that the vitrification cluster was closer to the fresh cluster, indicating that spermatozoa are better preserved through vitrification. In conclusion, while both slow freezing and vitrification have negative effects on sperm function and structure, the vitrification protocol described here had a relatively better recovery rate (65.8%) and showed improved preservation of several sperm quality parameters compared with slow freezing.

Phosphatidylcholine and L-acetyl-carnitine-based freezing medium can replace egg yolk and preserves human sperm function

Background

Conventional cryopreservation methods induce chemical and mechanical damage to the sperm membranes. The cryoprotectant potential of phospholipids of vegetal origin as soybean lecithin has been investigated as a substitute for egg yolk in diluents used for the cryopreservation of human spermatozoa. Therefore, the objective of this study was comparing the efficacy of a synthetic cryoprotectant supplemented with L-α-phosphatidylcholine (PC) and L-acetyl-carnitine (ANTIOX-PC) and the standard egg-based TEST-yolk buffer (TYB) in preserving sperm motility and chromatin quality in cryopreserved semen samples.

Methods

Prospective experimental study in which semen samples from 63 men with normal sperm motility and 58 men with low sperm motility were included and analyzed both before and after cryopreservation using ANTIOX-PC or TYB freezing media. Sperm quality was evaluated by routine semen analysis and DNA fragmentation index using the Terminal deoxynucleotidyl transferase dUTP nick end labeling assay.

Results

Differences in the post-thaw progressive motility and DNA fragmentation index were not detected between TYB and ANTIOX-PC cryoprotectants in both normal and low sperm motility groups (P>0.05). However, ANTIOX-PC medium retained higher non-progressive motility and lower percentage of immotile sperm when compared to TYB medium, resulting in a greater total motile sperm count (P<0.05), regardless baseline values of motility characteristic of the normospermic or asthenozoospermic samples.

Conclusions

ANTIOX-PC medium was effective to protect human sperm during a freeze-thaw cycle compared to the TYB medium. A clinically relevant advantage in better preserving kinetic parameters as higher total motility and lower immotile post-thawed sperm from ANTIOX-PC, in normal and low motility semen samples, demonstrated the positive impact of phospholipid and antioxidant treatment on sperm cryotolerance with high potential for egg yolk lipids replacement and biosafety.

Effects of freezing extender supplementation with mitochondria-targeted antioxidant Mito-TEMPO on frozen-thawed rooster semen quality and reproductive performance

Rooster semen cryopreservation is a useful method to utilize semen samples for artificial insemination in commercial flocks, but with use of the freezing-thawing process there is a reduction in the quality and fertilization capacity of rooster spermatozoa post-thawing. The aim of the current study was to investigate the efficacy of the mitochondria-targeted antioxidant Mito-TEMPO on rooster sperm quality and fertilization capacity after conducting the freezing-thawing processes. Semen samples were diluted and there were five equal aliquots supplemented with 0, 0.5, 5, 50 and 500 μM Mito-TEMPO. Semen samples were subsequently cryopreserved in liquid nitrogen. After thawing, sperm motility, lipid peroxidation, membrane functionality, normal morphology, mitochondria active potential, acrosome integrity, viability, apoptotic-like changes, DNA fragmentation, hydrogen peroxide concentration and fertilizing capacity were evaluated. Supplementation of Lake medium with 5 and 50 μM Mito-TEMPO resulted in greater (P ≤ 0.05) total sperm motility, progressive motility, average path velocity, membrane functionality, mitochondria active potential, acrosome integrity and viability compared with semen of the other groups. Lipid peroxidation, late apoptotic-like changes, DNA fragmentation and hydrogen peroxide content, however, were less (P ≤0.05) in semen samples supplemented with 5 and 50 μM Mito-TEMPO compared to other groups. Furthermore, fertility percentages were greater when there was supplementation with 5 and 50 μM Mito-TEMPO compared to the control group. Mitochondria-targeted antioxidant Mito-TEMPO could be included in semen extender before cryopreservation to improve quality and fertilization capacity of rooster semen after thawing of cryopreserved samples.

Proper cytoskeleton α-tubulin distribution is concomitant to tyrosine phosphorylation during in vitro capacitation and acrosomal reaction in human spermatozoa

Spermatozoa motility is a key parameter during the fertilization process. In this context, spermatozoa tyrosine protein phosphorylation and an appropriate cytoskeleton α-tubulin distribution are some of the most important physiological events involved in motility. However, the relationship between these two biomarkers remains poorly defined. Here, we characterized simultaneously by immunocytochemistry the α-tubulin (TUBA4A) distribution and the tyrosine phosphorylation at flagellum before capacitation, during different capacitation times (1 and 4 hr), and after acrosome reaction induction in human spermatozoa. We found that the absence of spermatozoa phosphorylation in tyrosine residues positively and significantly correlated (p < 0.05) with the terminal piece α-tubulin flagellar distribution in all physiological conditions. Conversely, we observed a positive significant correlation (p < 0.01) between phosphorylated spermatozoa and continuous α-tubulin distribution in spermatozoa flagellum, independently of the physiological condition. Similarly, the subpopulation of spermatozoa with tyrosine phosphorylated and continuous α-tubulin increases with longer capacitation times and after the acrosome reaction induction. Overall, these findings provide novel insights into the post-transcriptional physiological events associated to α-tubulin and the tyrosine phosphorylation during fertilization, which present potential implications for the improvement of spermatozoa selection methods.

Quantitative proteomic characterization of human sperm cryopreservation: using data-independent acquisition mass spectrometry

Background

Human sperm cryopreservation is a simple and effective approach for male fertility preservation.

Methods

To identify potential proteomic changes in this process, data-independent acquisition (DIA), a technology with high quantitative accuracy and highly reproducible proteomics, was used to quantitatively characterize the proteomics of human sperm cryopreservation.

Results

A total of 174 significantly differential proteins were identified between fresh and cryoperservated sperm: 98 proteins decreased and 76 proteins increased in the cryopreservation group. Bioinformatic analysis revealed that metabolic pathways play an important role in cryopreservation, including: propanoate metabolism, glyoxylate and dicarboxylate metabolism, glycolysis/gluconeogenesis, and pyruvate metabolism. Four different proteins involved in glycolysis were identified by Western blotting: GPI, LDHB, ADH5, and PGAM1.

Conclusions

Our work will provide valuable information for future investigations and pathological studies involving sperm cryopreservation.

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.

The anti-oxidant roles of Taurine and Hypotaurine on acrosome integrity, HBA and HSPA2 of the human sperm during vitrification and post warming in two different temperature

Despite advances in vitrification techniques for sperm cryopreservation, cryo-damages of sperm caused by generation of reactive oxygen species (ROS) continue to impede implementation of this technique. This study analyses the effects of taurine and hypotaurine as anti-oxidants during vitrification of human sperms. The study was performed in two steps. In the first step, 20 normospermic semen samples were vitrified in the presence of varying concentrations of taurine and hypotaurine, and their effects as anti-oxidant agents on classical sperm parameters, hyaluronan-binding assay (HBA), lipid peroxidation (LPO) and acrosome reaction (AR) were studied. Statistical analyses showed that the sperm parameters in all vitrified groups decreased significantly (P < 0.05) compared to the fresh group. However, HBA and acrosome integrity in vitrified groups containing taurine and 50 mM of hypotaurine were better than in the control group (P < 0.05). The morphology of the vitrified group was good only in the group that contained 50 mM of hypotaurine (P < 0.05). Based on the results from the first step, 50 mM of hypotaurine was considered the ideal anti-oxidant formulation and further tests were carried out on 10 normospermic semen samples with this protecting agent. In addition to the mentioned parameters, the expression of heat shock proteinA2 (HSPA2) was studied in the vitrified group with 50 mM hypotaurine, warmed under two different warming temperatures 37 and 42 °C. 50 mM Hypotaurine was found to equally improve motility, morphology, HBA, and AR after warming at 37 °C and 42 °C (P < 0.05). However, at both warming temperatures, the expression of HSPA2 was reduced in all vitrified groups comparing to the fresh group (P < 0.05). In conclusion, taurine and hypotaurine antioxidants, especially 50 mM hypotaurine, are able to reduce deleterious cryo-injuries on morphology, acrosome and HBA and improve sperm recovery at both warming temperatures (37 and 42 °C). However, they do not have any protective action on expression of HSPA2.

The Application of Ultrasonic Vibration in Human Sperm Cryopreservation as a Novel Method for the Modification of Physicochemical Characteristics of Freezing Media

The application of ultrasonic vibration was performed to modify the water molecules as the main compositions of the freezing medium used for human sperm cryopreservation. Different time periods of ultrasonic vibration (ULV) at the frequency of 28 kHz were applied for the evaluation of physicochemical properties of the water molecules. The most significant bubble size, zeta potential, and pH were obtained for the water molecules exposed to ultrasonic vibrations for 18 minutes and this time period was selected for further experiments due to the optimum results. In the next stage, semen samples were diluted with freezing medium containing ULV-exposed water and then cryopreserved. All the semen parameters were significantly reduced in cryopreserved groups as compared with the fresh control group. The highest percentage of total and progressive motility, viability, membrane and DNA integrity, and mitochondrial membrane potential were observed in frozen ULV compared with the frozen control. The rate of apoptosis in frozen ULV was significantly lower than that of in the frozen control. Furthermore, the gene expression ratios of α- and β-tubulins were significantly increased during cryopreservation, while the expression ratio of the tubulin polymerization promoting protein (TPPP) gene was decreased. Similar results were also observed when the protein levels of the genes mentioned earlier were evaluated by the ELISA method. Therefore, the changes in physicochemical properties of the freezing medium of human sperm cryopreservation using ULV can improve the quality of frozen products.

Cryopreservation of human spermatozoa by vitrification versus conventional rapid freezing: Effects on motility, viability, morphology and cellular defects

OBJECTIVES

Sperm cryopreservation has great potential for male infertility treatment as used in assisted reproduction technology (ART). There are a variety of cryopreservation methods in order to preserve sperm in a long term. Although conventional freezing and vitrification now are used widely, they have damage on sperm parameters as well as sperm DNA integrity. It is necessary to answer which method is better and appropriate for sperm cryopreservation. The aim of this study was to compare the effect of conventional freezing and vitrification regarding to motility, vitality and morphology of sperm found in washed and unwashed samples.

STUDY DESIGN

One hundred and five human fresh semen samples were divided into washed and unwashed halves using density-gradient centrifugation. Each group then was split into two aliquots: one cryopreserved by conventional freezing and the other by vitrification, using SpermFreeze Solution™ (Vitrolife, Västra Frölunda, Sweden) containing glycerol as a cryoprotectant. The sperm parameters were analyzed and compared between six groups: washed fresh (FW), unwashed fresh (FU), washed conventional freezing (CfW), unwashed conventional freezing (CfU), washed vitrification (VitW) and unwashed vitrification (VitU) samples.

RESULTS

Sperm progressive motility, vitality and normal morphology significantly decreased, together with an appreciable increase in sperm head, midpiece and tail defects when comparing to the fresh sperm parameters after thawing in all groups. In conventional freezing method groups, progressive motility and vitality were substantially higher than that in vitrification method groups. However, vitrification gave better results in normal morphology rates. Additionally, sperm head, midpiece and tail defects were significant lower in two vitrification groups in comparison with conventional freezing groups. Interestingly, washed groups had better sperm parameters than unwashed groups so that washing process before frozen seemed to improve sperm parameters.

CONCLUSION

Conventional freezing method resulted in better motility, viability in both washed/unwashed groups. On the contrary, spermatozoa undergoing vitrification were healthier regarding morphology with less defects than conventional freezing. Sperm washing before frozen was a beneficial preparation to sperm cryopreservation.

Human sperm acrosome function assays are predictive of fertilization rate in vitro: a retrospective cohort study and meta-analysis

OBJECTIVE

To determine whether acrosome function scoring-including acrosomal enzyme (AE) levels and acrosome reaction (AR) results-can predict fertilization rate in vitro.

METHODS

We examined the predictive value of acrosomal enzymes (AE) determined by spectrophotometry/N-α-benzoyl-DL-arginine-p-nitroanilide for fertilization rate (FR) in vitro in a retrospective cohort study of 737 infertile couples undergoing IVF therapy. Additionally, a meta-analysis was done for prospective cohort or case-control studies; the following summary measures were reported to expand upon the findings: pooled spearman correlation coefficient (Rs), standardized mean difference (SMD), sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic score (DS), diagnostic odds ratio (DOR), and area under the summary receiver operating characteristic curve (AUC).

RESULTS

Lower AE levels determined by spectrophotometry with a cut-off value of <25μIU/10⁶ spermatozoa were predictive of total fertilization failure (TFF) with moderate SEN (88.23%) and low SPE (16.50%). On meta-analysis, a total of 44 unique articles were selected, but given the multiple techniques described there was a total of 67 total datasets extracted from these 44 articles, comprising 5356 infertile couples undergoing IVF therapy. The AE levels or induced AR% was positively correlated with FR (Rs = 0.38, SMD = 0.79; Rs = 0.40, SMD = 0.86, respectively). Lower AE levels or induced AR% was predictive of lower fertilization rate with moderate accuracy (AUC = 0.78, AUC = 0.84, respectively); this was accompanied by low SEN/moderate SPE (0.57/0.85), moderate SEN/moderate SPE (0.79/0.87), respectively. For AE assay, the diagnostic performance in Asia (Rs = 0.24, SMD = 0.50) was inferior to that in North America (Rs = 0.54, SMD = 0.81) and Europe (Rs = 0.46, SMD = 0.92). Cryopreserved spermatozoa (SMD = 0.20, P = 0.204) were inferior to fresh spermatozoa (SMD = 0.89, P <  0.001). Sperm preparation yielded inferior results as compared to no preparation; spermatozoa after swim up were weak relevant (Rs = 0.27, P = 0.044); and there was no correlation for spermatozoa after a discontinuous gradient (SMD = 1.07, P >  0.05). Lower AE levels determined by fluorometry or substrate assay were used for predicting lower FR with low sensitivity and high specificity; the spectrophotometry assay had an uncertain predictive value. For induced AR assay, the diagnostic performance in the other areas was inferior to that in Africa (Rs = 0.65, SMD = 1.86). No preparation or double preparation yielded inferior results as compared to one preparation (Rs = 0.41); discontinuous gradient (Rs = 0.17, SMD = 0.47) was inferior to swim up (Rs =0.65, SMD = 1.51). Nonphysiological triggers (SMD = 0.81) did not differ from physiological triggers (SMD = 0.95) in general; ZP (Rs = 0.63) or mannose (Rs = 0.59) was superior to other physiological or nonphysiological triggers; and there was no correlation for human follicle fluid, progesterone, cyclic adenosine 3'-5'-phosphate analogue and phorbol ester-BSA-GlcNAc Neoglycoproteins with N-acetylglucosamine residues. Lower induced AR% determined by indirect immunofluorescence, direct immunofluorescence with lection, or triple stain was used for predicting lower FR, with moderate sensitivity/high specificity, moderate sensitivity/high specificity, or high sensitivity/low specificity.

CONCLUSIONS

Although the correlation between acrosome function scoring and FR was significant, the assays were neither highly sensitive nor specific. Additionally, the diagnostic performance showed regional effects as well as an effect of the sperm preparation or assay method. More studies of multicenter, large-scale, careful design and synthesizing multiple sperm functional assays and oocyte quality assays are still needed in clinical settings to better predict fertilization outcome in IVF.

iTRAQ-based analysis of sperm proteome from normozoospermic men achieving the rescue-ICSI pregnancy after the IVF failure

Background

In the assisted reproduction, the infertile molecules of spermatozoa from normozoospermic men who underwent the unexplained failure of in vitro fertilization (IVF) due to the lack of sperm binding to the normal zona pellucida, and then achieved pregnancy with the rescue intracytoplasmic sperm injection (R-ICSI) remain unclear. More works are still necessary to explore this male infertile mechanism.

Methods

Normozoospermicmen with the IVF pregnancy and normozoospermic men with the R-ICSI pregnancy after the conventional IVF failure were collected. iTRAQ-based proteomic approach were performed to reveal the new infertile causes between the IVF pregnancy men and the R-ICSI pregnancy men. To validate the confidence of proteome data, the individual samples were analyzed by western blot and immunofluorescence. Further, the spontaneous acrosome reactions were measured to evaluate the sperm quality.

Results

Compared with IVF pregnancy group, 56 sperm proteins were differentially expressed in the R-ICSI pregnancy group. Bioinformatic analyses (PANTHER, DAVID, PubMed and STRING) indicated these altered sperm proteins were involved in various molecular functions: reproduction, chromosome organization, and sperm-oocyte interaction. Moreover, the confidence of proteome data was confirmed by western blot and immunofluorescence using the individual samples, which were consistent with our proteomic data. Additionally, an increased rate of the spontaneous acrosome reaction rate was found in the R-ICSI pregnancy group.

Conclusions

The sealtered sperm proteins and the increased spontaneous acrosome reaction rate might account for this unexplained male infertility in the R-ICSI pregnancy patients. The present proteomic results will throw light on the better understanding of the unexplained infertile mechanisms underlying these normozoospermic man who achieved R-ICSI pregnancy after IVF failure.

Electronic supplementary material

The online version of this article (10.1186/s12014-018-9203-3) contains supplementary material, which is available to authorized users.

Cryopreservation media differentially affect sperm motility, morphology and DNA integrity

INTRODUCTION

Human sperm freezing is very widely used for male fertility preservation. This procedure consists in adding cryoprotectants to the spermatozoa followed by cooling and storing the spermatozoa at a subzero temperature. Many standardized cryopreservation media are available on the market. However, these media differ in their chemical composition and there are no sufficient data to optimize their classification. Therefore, the aim of this study was to compare five commercially available sperm cryopreservation media, which have not been compared together, in terms of motility, morphology and DNA integrity.

MATERIALS AND METHODS

One-hundred semen samples were obtained from 10 fertile participants and 90 infertile men. Each sample was evaluated before freezing for motility, morphology and DNA fragmentation index (DFI). Then, it was equally divided into five aliquots. Each aliquot was cryopreserved using one of the five media (A, B, C, D, and E). The same parameters were re-evaluated after the addition of the cryopreservation media in the fertile group, and after sperm thawing in fertile and infertile groups.

RESULTS

The results showed that the five selected cryopreservation media had negative effects on sperm motility and morphology per se. In the infertile group, the cryosurvival factor was significantly lower in cryomedium A when compared to the four other media (p < 0.001). In addition, a significantly higher percentage of sperm with coiled tail was detected in cryomedium E compared to cryomedium A (p < 0.05) and to cryomedium B (p < 0.001) after thawing, in the infertile group. Furthermore, the sperm DFI was significantly higher in cryomedia A (p < 0.001), B (p < 0.001), C (p < 0.01), D (p < 0.01) and E (p < 0.05) compared to that of the fresh semen derived from infertile participants.

CONCLUSION

This study indicates that the recovery rate of competent spermatozoa, after cryopreservation, is still critical in infertile men. Therefore, frozen semen sample should be used only when necessary.

Proteomic analysis and microtubule dynamicity of human sperm in electromagnetic cryopreservation

The proteomic changes, microtubule dynamicity, and quality parameters of human sperm were investigated during cryopreservation in an extremely low electromagnetic field (ELEF) condition. Semen samples were obtained from 210 healthy individuals with normospermia and then were divided into three experimental groups: fresh control, frozen control, and frozen ELEF group. Shotgun proteomics was performed to assess the identification of microtubule proteins of the sperm in experimental groups. Microtubule dynamicity, secondary, and tertiary structure modifications of tubulins, characteristics of transmission electron microscopy of sperm as well as sperm quality parameters were evaluated. The expression ratios of α- and β-tubulins were significantly increased after cryopreservation compared with fresh control while this ratio was not significantly different in frozen ELEF group. The expression ratio of tubulin polymerization-promoting protein was significantly decreased after cryopreservation compared with fresh control. The length, width, and the activity of microtubule, secondary, and tertiary structures of tubulins, motility, and the viability of the sperm were decreased in frozen control as compared with fresh control. The microtubule activity, secondary, and tertiary structures of sperm tubulin in frozen ELEF group were higher than frozen control. Transmission electron microscopy of microtubules showed that the size of the width and length of the microtubules in frozen ELEF group were greater than frozen control. Motility, viability, and reactive oxygen species levels were improved in frozen ELEF group when compared with frozen control. While the microtubule dynamicity of the sperm was affected by the cryopreservation, this trait was improved during the electromagnetic cryopreservation resulted in better motility and viability.

Comparison of intracytoplasmic sperm injection outcome with fresh versus frozen-thawed testicular sperm in men with nonobstructive azoospermia: a systematic review and meta-analysis

PURPOSE

The purpose of the study is to explore testicular sperm cryopreservation in patients with nonobstructive azoospermia (NOA) whether affect the outcome of subsequent intracytoplasmic sperm injection (ICSI).

METHODS

A systematic review and meta-analysis was conducted by searching the MEDLINE and EMBASE databases for relevant published studies in English language (1997-2017). Studies were eligible if they included the comparison of using fresh and frozen-thawed testicular sperm followed by ICSI. Two reviewers independently performed data extraction, quality assessment and assessed the risk of bias. The overall summary risk estimated the number of events. A meta-analysis was conducted using a random effects or fixed effects model analysis according to the test of heterogeneity.

RESULTS

A total of 17 studies with 1,261 ICSI cycles were identified. Analysis of the present data showed no difference in the fertilization outcome when comparing fresh versus frozen-thawed spermatozoa (RR = 1.02, 95% CI 0.86-1.09). Similarly, no difference in CR (RR = 1.01, 95% CI 0.96-1.05), good embryo rate (RR = 1.01, 95% CI 0.95-1.09), and IR (RR = 0.93, 95% CI 0.66-1.30) was observed if the spermatozoa was fresh or frozen-thawed. Finally, no difference in CPR or LBR was noted when using fresh or frozen-thawed cycles were analyzed separately (RR = 1.03, 95% CI 0.86-1.24; RR 1.11, 95% CI 0.88-1.41, respectively).

CONCLUSIONS

In men with NOA, the ICSI outcome is not affected by whether the retrieved testicular sperm is fresh or frozen. Sperm cryopreservation ought to be considered in every surgical sperm retrieval case, which remain feasible even in patients with few testicular sperm retrieved.