Implication of apoptosis in sperm cryoinjury

From TCM "Shen-nourishing" and "Yang-strengthening" theory to Blood-Testis Barrier Reorganization,GuiLuBuShen Attenuates Age-Related Male Reproductive Dysfunction

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese Medicine (TCM) provides a theoretical foundation for treating reproductive dysfunction via "Shen" system regulation. The classical formulation GuiLuBuShen pill (GLBS), recognized as a principal TCM therapy for male urogenital disorders, clinically enhances "Shen-Yang" nourishment in middle-aged and elderly males with genitourinary degeneration.

AIM OF THE STUDY

This study aims to elucidate the therapeutic efficacy and molecular mechanisms underlying GLBS in mitigating age-associated male genitourinary dysfunction, with particular focus on its regulatory effects on "Shen" deficiency-related pathophysiology during reproductive system senescence.

MATERIALS AND METHODS

In this study, 14-month-old Wistar rats were used to model natural male aging (vs. 6-week controls), and GLBS was administered at low (0.81g/kg/d), medium (1.62g/kg/d), and high (3.24 g/kg/d) doses for 8 weeks. The multimodal evaluation comprised physiological aging markers (body condition/fatigue recovery), reproductive competence (hormonal profiles/mating behavior/sperm parameters), organ integrity (morphometrics/urogenital histopathology) and molecular mechanisms (testicular transcriptomics & pathway validation).

RESULTS

GLBS treatment effectively attenuated age-related physiological decline, including weight loss, thermoregulatory dysfunction, and loco-motor impairment in open field test. Systemic anti physiological stress effects were demonstrated through reduced serum corticosterone, decreased organ degeneration and suppressed prostatic oxidative stress. GLBS restored reproductive function via reduced testicular oxidative damage, hormonal rebalancing, improved sperm motility/viability and attenuated seminiferous tubule degeneration with suppressed germ cell apoptosis. Mechanistic studies revealed that these effects were mechanistically linked to blood-testis barrier reinforcement and steroidogenic activation, collectively preserving spermatogenic homeostasis.

CONCLUSIONS

GLBS emerges as a multi-target therapeutic candidate for age-related urogenital disorders, uniquely combining systemic anti-aging effects with direct testicular rejuvenation. Its dual-action mechanism coordinates blood-testis barrier reinforcement through junctional remodeling with endocrine rebalancing, effectively preserving spermatogenic microenvironment homeostasis. The findings provide translational validation of traditional "Shen-nourishing" theory through contemporary molecular evidence, positioning GLBS as a promising intervention addressing both systemic senescence and organ-specific pathophysiology in male reproductive aging.

Do Linalool-Loaded Solid Lipid Nanoparticles Improve the Quality of Naval Medical Research Institute Mouse Sperm During Freezing/Thawing and Handling Processes?

Introduction: Handling, freezing, and thawing of sperm causes oxidative stress, compromising sperm quality. Nanotechnology offers platforms for the smart delivery of antioxidants during these processes. Objectives: A solid lipid nanoparticle (SLN) was used to deliver linalool, as an antioxidant supplementation to Naval Medical Research Institute mouse sperm during handling, freezing, and thawing. Methods: Linalool-loaded solid lipid nanoparticle (L-SLN) was made using the self-assembly method. After the assessment of physicochemical properties, the impact of L-SLN (10, 20, 30, and 50 µg/mL) on sperm motility, viability, sperm DNA fragmentation (SDF), nitric oxide (NO) production, and the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT), was investigated after its addition to the handling, freezing, and thawing media. Results: L-SLN was successfully created with a size of 262 ± 9.5 and a zeta potential of -28.5 ± 7.12, with an extended-release over time. During handling and freezing, supplementing corresponding media with L-SLN resulted in increased sperm motility and viability, specifically at 30 µg/mL. The percentage of SDF also decreased in post-thawed sperm at 30 µg/mL. L-SLN also led to elevated post-thawed NO production at 20 µg/mL, as well as increased SOD activity at 20 and 30 µg/mL. It also enhanced CAT and GPx activity at 30 and 10 µg/mL respectively. In handling media, L-SLN at 10 µg/mL could enhance NO production, CAT, and SOD activity, and at 20 µg/mL also boosted NO production and GPx activity. Generally, there was no significant improvement in sperm parameters with the mutual concentration of L-SLN for thawing media. Conclusions: Treating sperm extender media with 20 and 30 µg/mL of L-SLN and handling media with 10 and 30 µg/mL of L-SLN could improve sperm parameters following these interventions. L-SLN is a new antioxidant for sperm handling and freezing media, which may be applicable in human reproductive efforts.

The Effect of Edaravone Supplementation Prior to Cryopreservation on Sperm Parameters, DNA Integrity, Apoptosis, Lipid Peroxidation, and Mitochondrial Membrane Potential in Infertile Men with Asthenoteratozoospermia

Male infertility is a worldwide problem, and many couples have suffered from it. Although cryopreservation is widely used for the long-term preservation of human sperm, sperm survival, and function post-thawing procedure may be strongly impaired and thus decrease the reproductive performance. This study examined whether adding Edaravone before cryopreservation could improve the post-thaw parameters (especially sperm motility) of cryopreserved spermatozoa in patients with asthenoteratozoospermia (AT). Semen samples were collected by masturbation from 25 men with AT and assessed following WHO standards. Samples were divided into three aliquots. The first aliquot remained untreated and freshly assessed (fresh group). The second aliquot was untreated, mixed with a cryopreservation medium, and cryopreserved (freeze group). The third aliquot was treated with ten µM Edaravone, mixed with cryopreservation medium, and cryopreserved (freeze + Edaravone group). The groups were assessed for motility, morphology, viability, apoptosis, lipid peroxidation, Mitochondrial Membrane Potential (MMP), DNA Fragmentation Index (DFI), glutathione (GSH), ATP, and ROS production. The freeze + Edaravone group significantly improved total sperm motility (P < 0.0001), progressive and non-progressive sperm motility (P < 0.01), viability (P < 0.0001), morphology (P < 0.001), DFI (P < 0.0001) and live sperm cells (P < 0.0001) post-thawing compared to freeze group. Additionally, the freeze + Edaravone group significantly decreased necrotic sperm cells (P < 0.0001), lipid peroxidation (P < 0.0001), and intracellular ROS production (P < 0.0001) post-thawing procedure. Furthermore, the freeze + Edaravone group significantly enhanced MMP jc-1 orange and green (P < 0.0001 and P < 0.01, respectively), ATP production (P < 0.0001), and GSH levels (P < 0.0001) post-thawing procedure compared to freeze group. Our findings proved that the freeze + Edaravone group of men with AT improved sperm survival and functions post-thawing procedure.

Ellagic acid maintains post-thaw goat sperm quality via protecting mitochondrial function from ROS damage

This study aimed to investigate the effects of ellagic acid (EA), an antioxidant, on goat sperm quality after freezing and thawing. Goat semen was frozen using Tris-citric acid-glucose (TCG) extender containing 0, 1.25, 2.5, 5, and 10 μM of EA. Egg yolk represented 20 % (v/v) and glycerol represented 5 % (v/v) of the extender's final concentration. Goat sperm post-thaw motility, acrosome integrity, plasma membrane integrity, mitochondrial activity, ATP content, NADH/NAD+ levels, and NADH-CoQ activity were evaluated. Moreover, to elucidate how EA enhanced the goat sperm characteristics, the post-thaw sperm mitochondrial reactive oxygen species (ROS) level, malondialdehyde (MDA) level, oxidative DNA damage, apoptosis, levels of NADH dehydrogenase 1 (MT-ND1) and NADH dehydrogenase 6 (MT-ND6) proteins, and the 4-hydroxynonenal (4-HNE) level were also measured after thawing. The results demonstrated that motility, plasma membrane integrity, and acrosome integrity rates were enhanced in the group treated with 5 μM of EA compared to the other concentrations (0 μM, 1.25 μM, 2.5 μM, 5, and 10 μM). Moreover, mitochondrial activity and ATP content were notably superior in the 5 μM EA group compared to all other treatment groups, along with a considerable decrease in ROS and MDA levels. The 4-HNE level and oxidative DNA damage in sperm were also reduced by EA supplementation. Additionally, it was found that EA (5 μM) significantly (p < 0.05) decreased sperm apoptosis levels. Furthermore, the addition of 5 μM EA maintained the post-thaw sperm MT-ND1 and MT-ND6 levels and reduced the negative impact of ROS on MT-ND1 and MT-ND6, thereby sustaining mitochondrial function for ATP generation. These results suggest that ellagic acid supplementation could maintain goat post-thaw sperm quality by reducing ROS damage and maintaining mitochondrial function for ATP generation. Antioxidant treatments, such as ellagic acid are a useful tool for maintaining frozen-thawed sperm quality.

Supplementation of DHA enhances the cryopreservation of yak semen via alleviating oxidative stress and inhibiting apoptosis

Introduction

Semen cryopreservation is a crucial method for preserving genetic resources and accelerating the breeding process in domestic animals. However, the frozen-thawed process often leads to physical and chemical damage in semen, resulting in oxidative stress that diminishes sperm vitality and fertilization potential. This study aimed to explore the effects of docosahexaenoic acid (DHA) on the quality of frozen-thawed yak semen.

Methods

Semen samples were collected from six healthy adult Maiwa yaks and cryopreserved in liquid nitrogen using extenders with varying DHA concentrations: 0, 0.1, 1, 10, and 100 ng/mL. After thawing, we assessed indices, antioxidant capacity, mitochondrial activity, and apoptosis status to identify the optimal DHA concentration.

Results and discussion

Our findings indicate that the addition of DHA significantly improved the total motility (TM), progressive motility (PM), velocity of straight line (VSL), curvilinear velocity (VCL), and average path velocity (VAP) of cryopreserved spermatozoa, as well as the integrity of membrane and acrosome (P < 0.05). Additionally, DHA supplementation markedly reduced the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) in frozen-thawed yak spermatozoa (P < 0.05) and enhanced the antioxidant enzyme activities (T-AOC, SOD, CAT, GSH-Px, P < 0.05). It also improved the mitochondrial membrane potential (MMP) and ATP levels (P < 0.05). Notably, the group treated with 10 ng/mL DHA showed significantly better outcomes than the other treatment groups (P < 0.05). Furthermore, the addition of 10 ng/mL DHA to the semen cryopreservation dilution effectively decreased the apoptotic ratio of frozen-thawed yak spermatozoa (P < 0.05), and notably upregulated the expression level of anti-apoptotic protein Bcl-2 (P < 0.05), while downregulating the expression of the pro-apoptotic protein Bax and Caspase3 (P < 0.05).

Conclusion

In conclusion, the incorporation of 10 ng/mL DHA into semen extenders enhances the quality and viability of yak sperm after cryopreservation by alleviating the oxidative stress, bolstering antioxidant defenses, and preserving mitochondria function, as well as inhibiting the apoptotic pathway activation.

Effect of Centrifuged Chicken Egg Yolk on the Cryopreservation of Boar Semen

Egg yolk, commonly employed as a cryoprotectant in semen cryopreservation, contains large particle matter that can diminish semen quality post thaw and complicate its quality assessment. For this reason, we designed a centrifugal treatment of chicken egg yolk to evaluate its effect on the cryopreservation of porcine semen. The control group (CG) was prepared with a dilution of chicken egg yolk by conventional mixing treatment, and the experimental group (EG) used a dilution of centrifugally treated chicken egg yolk for the ultra-low-temperature cryopreservation of porcine semen. The freezing process was carried out by conventional freezing methods. The spermatozoa were subsequently assessed for various parameters, including motility, acrosome integrity rate, plasma membrane integrity rate, antioxidant indexes, apoptosis rate, and the expression of apoptosis-related genes. The results showed that, post freeze-thawing, the motility, viability, VSL, and VCL of the spermatozoa in the EG were significantly higher than those observed in the CG (p < 0.05). Additionally, the acrosome integrity and plasma membrane integrity of the spermatozoa in the EG were significantly enhanced compared to the CG (p < 0.05). Furthermore, the EG exhibited significantly lower MDA content and sperm apoptosis rate (p < 0.05), while demonstrating significantly higher T-AOC and CAT levels (p < 0.05) relative to the CG. In comparison to the CG, the EG exhibited a significant reduction in the gene expression of TNF-a and Bax in the spermatozoa (p < 0.05), whereas the expression levels of CAT and Bcl-2 were significantly elevated (p < 0.05). In conclusion, the dilution solution formulated through the centrifugal processing of chicken egg yolk demonstrated efficacy in enhancing the quality of porcine spermatozoa following cryopreservation and subsequent thawing.

Ferroptosis emerges as the predominant form of regulated cell death in goat sperm cryopreservation

BACKGROUND

Freezing-induced sperm damage, often associated with oxidative stress, can result in regulated cell death. Given that oxidative stress can trigger various forms of regulated cell death, the prevailing form during sperm cryopreservation remains unknown. Our study aimed to investigate this issue using cashmere goats as a model.

RESULTS

We found a significant increase in lyso-phospholipids in frozen-thawed sperm suggested ferroptosis. Assessment of cryopreserved sperm, with or without prior treatment with ferroptosis or apoptosis inhibitors, demonstrated the significant efficacy of ferroptosis inhibitors in reducing freezing damage. This implicates ferroptosis as the primary form of regulated cell death induced during sperm cryopreservation. Additionally, the positive rate of transferrin receptor protein 1 was significantly lower in fresh live sperm (47.8%) than in thawed live sperm (71.5%), and the latter rate was lower than that in dead sperm (82.5%). By contrast, cleaved caspase-3 positivity showed no significant difference between fresh live sperm and thawed live sperm but was notably lower in thawed live sperm than in dead sperm.

CONCLUSIONS

Our findings establish ferroptosis as the dominant regulated cell death form during goat sperm cryopreservation, providing novel insights into freezing-induced sperm damage mechanisms. These findings have significant implications for optimizing cryopreservation protocols and enhancing sperm viability after freezing-thawing.

Attenuation of Chronic Oxidative Stress-Induced Testicular and Epididymal Dysfunction by Oral Intake of Lepidium meyenii in New Zealand Rabbits

Lepidium meyenii (Maca) is a plant that has nutritional benefits and increases the effectiveness of male reproduction. In this study, oxidative stress-exposed New Zealand rabbits were used to assess the ameliorative effects of daily Maca ingestion on testicular and epididymal tissues as well as the quality of fresh and frozen/thawed sperm. Twenty-four 40-week-old, healthy New Zealand white male rabbits were divided into four groups. The first group consumed tap water and served as a control. The second group was given 300 mg of Maca daily in capsules. The third group drank water containing hydrogen peroxide (H2O2) at a concentration of 1%. Finally, the fourth group consumed H2O2 and Maca daily. The ejaculate volume, sperm concentration, vitality, motility and velocity of the H2O2 group were considerably lower than those of the other groups. Frozen/thawed spermatozoa showed more dramatic decreases in motility and velocity as a result of H2O2 consumption. The plasma concentrations of testosterone and total antioxidant capacity were also lowest in the H2O2-treated rabbits, while malondialdehyde levels were highest. Exposure to H2O2 increased collagen deposition between ST and epididymal ducts which induced testicular and epididymis fibrosis. In addition, the spermatogenic and epididymal epithelial cells exhibited signs of apoptosis, degeneration, vacuolation and a reduction in height. Maca intake attenuated most of the damaging effects of H2O2 ingestion-induced oxidative stress. Furthermore, H2O2-treated rabbits had modest nuclear androgen receptor positivity, unlike those in the Maca group. The number of Leydig cells significantly increased with daily Maca intake. In conclusion, daily intake of Maca improved reproductive performance and mitigated the damaging effects of oxidative stress on testicular and epididymal functions in New Zealand rabbits.

Effect of freezing and thawing on ejaculated sperm and subsequent pregnancy and neonatal outcomes in IVF

Background

Techniques for sperm cryopreservation have exhibited their potential in male fertility preservation. The use of frozen-thawed sperm in in vitro fertilization (IVF) cycles is widespread today. However, many studies reported that cryopreservation might have adverse effects on sperm DNA integrity, motility, and fertilization, probably due to cold shock, intra- and extracellular ice crystals, and excess reactive oxygen species (ROS). Studies suggested that freezing and thawing impaired sperm viability and might adversely affect subsequent fertilization and pregnancy outcomes. The potential damage to fertilization and subsequent embryonic development and offspring health raises the concern on sperm cryopreservation. However, the above mentioned studies are limited to intracytoplasmic sperm injection (ICSI) cycles, while IVF is a more natural and patient-friendly method. IVF requires a higher quality of sperm than ICSI. However, the effect of freezing and thawing on sperm used for IVF remains unknown. Therefore, we aim to investigate the effect of freezing and thawing on ejaculated sperm and subsequent pregnancy and neonatal outcomes in IVF.

Methods

This retrospective cohort study at a tertiary-care academic medical center included 447 women who used paternal frozen-thawed ejaculated sperm and 31,039 women who used paternal freshly ejaculated sperm for IVF and underwent frozen-thawed blastocyst transfer from January 2011 to September 2021. To balance the baseline characteristics of the two groups, patients using frozen sperm were matched with control groups using a propensity score matching algorithm with a ratio of 1:3.

Results

Although sperm motility decreased from 82.04% to 75.70% (P < 0.001) after the freezing-thawing process, the fertilization rate (68.27% for frozen sperm and 67.54% for fresh sperm), number of viable embryos (1.98 and 2.16), clinical pregnancy rate (44.7% and 51.8%), and live birth rate (40.3% and 42.4%) were comparable between the two groups (all P > 0.05). For neonatal outcomes, no between-group differences were observed in offspring gender, gestational age, birthweight, and the rate of preterm birth (21.7% and 12.9%), low birthweight neonates (19.2% and 16.0%), and birth defects (0.0% and 0.8%) (all P>0.05).

Conclusions

Frozen-thawed sperm had lower sperm motility but resulted in comparable embryonic, pregnancy, and neonatal outcomes versus fresh sperm in IVF cycles.

Manila duck (Cairina moschata) frozen semen quality in lactated ringer's egg yolk-astaxanthin with different concentrations of DMSO

This study was conducted to evaluate manila duck's (Cairina moschata) frozen semen quality after cryopreservation in lactated ringer's egg yolk-astaxanthin (LREY-A) with 5 different concentrations of dimethyl sulfoxide (DMSO). Methodology: Semen was collected from 3 manila ducks (Cairina moschata) using the cloaca massage technique twice a week. Fresh semen was evaluated macro and microscopically then polled and divided into 5 tubes of treatments. Each tube was diluted in DMSO4, DMSO6, DMSO8, DMSO10, and DMSO12. The semen of each treatment was loaded into a 0.25 mL straw and equilibrated at 5 °C for 2 h. Freeze above nitrogen vapor and stored a container of liquid nitrogen at -196 °C, then semen thawed in a water bath at 37 °C for 30 sec. Data were analyzed using One-Way ANOVA Analysis. Results of this showed that post-equilibration sperm motility and sperm viability have differed significantly (P<0.05) for each treatment, with the highest % sperm motility DMSO8 and DMSO6, this is also shown in post-thawing sperm motility and viability which have differed significantly (P<0.05) and the highest % sperm viability were DMSO8 and DMSO6. In conclusion, Frozen semen extender formulation of DMSO8 and DMSO6 which are used in manila duck semen cryopreservation was the best to other treatments to maintain % sperm motility and % sperm viability in post-equilibration and post-thawing. The highest sperm motility recovery rate was in DMSO8. The lowest sperm live and dead abnormality was in DMSO8. It is concluded that the combination of DMSO8 was the best in maintaining the quality of manila duck frozen semen.

Crosstalk Between Oxidative Stress and Epigenetics: Unveiling New Biomarkers in Human Infertility

The correlation between epigenetic alterations and the pathophysiology of human infertility is progressively being elucidated with the discovery of an increasing number of target genes that exhibit altered expression patterns linked to reproductive abnormalities. Several genes and molecules are emerging as important for the future management of human infertility. In men, microRNAs (miRNAs) like miR-34c, miR-34b, and miR-122 regulate apoptosis, sperm production, and germ cell survival, while other factors, such as miR-449 and sirtuin 1 (SIRT1), influence testicular health, oxidative stress, and mitochondrial function. In women, miR-100-5p, miR-483-5p, and miR-486-5p are linked to ovarian reserve, PCOS, and conditions like endometriosis. Mechanisms such as DNA methylation, histone modification, chromatin restructuring, and the influence of these non-coding RNA (ncRNA) molecules have been identified as potential perturbators of normal spermatogenesis and oogenesis processes. In fact, alteration of these key regulators of epigenetic processes can lead to reproductive disorders such as defective spermatogenesis, failure of oocyte maturation and embryonic development alteration. One of the primary factors contributing to changes in the key epigenetic regulators appear to be oxidative stress, which arises from environmental exposure to toxic substances or unhealthy lifestyle choices. This evidence-based study, retracing the major epigenetic processes, aims to identify and discuss the main epigenetic biomarkers of male and female fertility associated with an oxidative imbalance, providing future perspectives in the diagnosis and management of infertile couples.

Assessing the efficacy of a novel sperm-washing medium enriched with serotonin, L-carnitine, and coenzyme Q10: an observational cohort study

ABSTRACT

This observational cohort study investigated the potential of a novel sperm-washing medium (SWM) enriched with serotonin (5-HT), L-carnitine (L-C), and coenzyme Q10 (CoQ10) to enhance sperm motility and reduce DNA damage. It compared this innovative medium (5-HT/L-C/CoQ10 SWM) with two widely used commercial media (SWM 1 and SWM 2). Ninety-eight volunteers from an infertility clinic provided semen samples, which were divided into three aliquots for analysis in different SWMs: group 1, SWM was composed of hydroxyethyl piperazineethanesulfonic acid (HEPES), sodium bicarbonate, human serum albumin (HSA), taurine, and gentamicin sulfate (SWM 1); group 2, SWM was composed of HEPES, sodium bicarbonate, and HSA (SWM 2); and group 3, SWM was composed of HEPES-buffered human tubal fluid supplemented with 5-HT, L-C, and CoQ10 (5-HT/L-C/CoQ10 SWM). Sperm motility was categorized as progressive, nonprogressive, or immotile. Apoptosis, reactive oxygen species (ROS) production, and DNA fragmentation were also assessed. There were no significant differences in total or progressive sperm motility among the groups. Spermatozoa in group 3 exhibited reduced apoptosis, necrosis, and ROS levels and increased viability. No significant differences were observed in the DNA fragmentation index among groups. The 5-HT/L-C/CoQ10 SWM reduced sperm oxidative stress and apoptosis compared with those of the two commercially available SWMs, suggesting that 5-HT/L-C/CoQ10 SWM could be useful for enhancing in vitro fertilization success rates.

Improvement of Post-Thaw Quality and In Vivo Fertility of Simmental Bull Spermatozoa Using Ferulic Acid

BACKGROUND

Artificial insemination and semen cryopreservation have significantly improved the quality and quantity of cattle production. Through cryopreserved semen and artificial insemination, top-breeding bull sperm can be used to inseminate thousands of cows worldwide.

OBJECTIVES

Our study aimed to determine the effect of adding ferulic acid (FA) to a Tris-based semen extender on frozen and thawed Simmental bull sperm.

METHODS

Semen samples were collected from three Simmental bulls. Pooled Simmental semen (n = 34 ejaculations) were diluted with a Tris-base extender containing varying FA concentrations (0.1, 0.15, 0.25, 0.35, and 0.45 mM). After the samples were frozen and thawed, the samples were tested for malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione peroxidase (GPx), total motility, progressive motility, motility characteristics, and plasma membrane functionality.

RESULTS

The control and the groups with the best FA concentrations, 0.25 and 0.35, were compared for in vivo fertility. Fifty-one cows were inseminated 24 h after the onset of oestrus. A rectal examination was used to diagnose pregnancies at least 60 days after fertilization. Results showed that adding FA-0.45, FA-0.35, FA-0.25, and FA-0.15 to the semen of Simmental bulls improved total and progressive motility, motility characteristics, and plasma membrane functionality. It also increased GPx and TAC levels, reducing MDA and DNA damage after freezing. The addition of FA did not affect SOD values. The fertility rate in the FA-0.25 and FA-0.35 groups was higher than in the control group, 35.29%, with rates of 76.47% and 70.58%, respectively.

CONCLUSIONS

In conclusion, adding FA (0.15, 0.25, 0.35, and 0.45 mM) to Tris-based semen extenders can improve the quality parameters of cryopreserved Simmental bull semen and increase in vivo fertility using 0.25 and 0.35 concentrations of FA.

Post-thaw quality assessment of testicular fragments as a source of spermatogonial cells for surrogate production in the flatfish Solea senegalensis

Cryopreservation of germ cells would facilitate the availability of cells at any time allowing the selection of donors and maintaining quality control for further applications such as transplantation and germline recovery. In the present study, we analyzed the efficiency of four cryopreservation protocols applied either to isolated cell suspensions or to testes fragments from Senegalese sole. In testes fragments, the quality of cryopreserved germ cells was analyzed in vitro in terms of cell recovery, integrity and viability, DNA integrity (fragmentation and apoptosis), and lipid peroxidation (malondialdehyde levels). Transplantation of cryopreserved germ cells was performed to check the capacity of cells to in vivo incorporate into the gonadal primordium of Senegalese sole early larval stages (6 days after hatching (dah), pelagic live), during metamorphosis (10 dah) and at post-metamorphic stages (16 dah and 20 dah, benthonic life). Protocols incorporating dimethyl sulfoxide (DMSO) as a cryoprotectant showed higher number of recovered spermatogonia, especially in samples cryopreserved with L-15 + DMSO (0.39 ± 0.18 × 106 cells). Lipid peroxidation and DNA fragmentation were also significantly lower in this treatment compared with other treatments. An important increase in oxidation (MDA levels) was detected in samples containing glycerol as a cryoprotectant, reflected also in terms of DNA damage. Transplantation of L-15 + DMSO cryopreserved germ cells into larvae during early metamorphosis (10 dah, 5.2 mm) showed higher incorporation of cells (27.30 ± 5.27%) than other larval stages (lower than 11%). Cryopreservation of germ cells using testes fragments frozen with L-15 + DMSO was demonstrated to be a useful technique to store Senegalese sole germline.

In vitro versus cryo-induced capacitation of bovine spermatozoa, part 3: Compositional and molecular changes to the plasma membrane

The aim of this study was to assess the level of membrane cryodamage through the levels of selected capacitation and apoptosis-associated proteins, together with compositional membrane changes in capacitated (CAP), cryopreserved (CRYO) and non-capacitated bovine spermatozoa (CRTL). Sperm kinetic parameters were analyzed by the computer assisted sperm analysis (CASA) while the capacitation patterns were examined with the chlortetracycline (CTC) assay. In the case of DNA integrity, sperm chromatin structure assay and aniline blue staining were used. For the quantification of fatty acid content gas chromatography was performed. Using Western blotting the expression of capacitation (protein kinase C - PKC; phospholipases A2 and Cζ - PLA2, PLCζ; soluble adenylyl cyclase 10 - sAC10) and apoptosis-associated (apoptosis regulator Bax; B-cell lymphoma 2 - Bcl-2; caspase 3) proteins were evaluated. Data indicate a significant decline (p < 0.0001) of sperm kinetic parameters and higher occurrence (p < 0.0001) of DNA fragmentation in the CRYO group. CTC assay revealed a significant increase of acrosome-reacted spermatozoa in the CRYO group when compared to others. Compositional changes in the sperm membrane were visible as a notable decline of docosahexaenoic acid (p < 0.0001) associated with a significant decrease of membrane cholesterol (p < 0.05) and proteins (p < 0.0001) in the CRYO group while the amount of palmitic, stearic, oleic, and linoleic acid increased (p < 0.0001) significantly. Protein expression of all capacitation-associated proteins (PKC, PLA2, PLCζ, sAC10) was significantly down-regulated (p < 0.001; p < 0.0001) in the CRYO group. Relative quantification of apoptosis-associated proteins revealed increased Bax and decreased Bcl-2 levels in the CRYO group, except for caspase-3, which remained without significant changes.

Flavone and 3-hydroxyflavone supplementation in cryopreservation medium protects canine sperm against apoptosis and lipid peroxidation

Cryopreservation is a pivotal technique in safeguarding genetic material across diverse species, despite its inherent challenges linked to induced spermatozoa damage, notably apoptosis and lipid peroxidation (LPO). Given the insufficient antioxidant defense of spermatozoa against LPO, there is a rising interest in integrating additional additives into extenders to ameliorate mammalian semen quality. Among these additives, flavonoids have garnered considerable attention due to their potent antioxidative properties. Hence, our study aimed to assess the efficacy of flavone (FL) and 3-hydroxyflavone (3-OH = ) supplementation in the cryopreservation medium to protect canine sperm against the damaging impacts of freezing and ensure the preservation of their reproductive potential. Semen was collected from five Beagle stud dogs and then pooled. Then, the sample was divided into 7 groups, each treated with 1) 0 mM, 2) 0.1 mM FL, 3) 0.2 mM FL, 4) 0.4 mM FL, 5) 0.1 mM 3-OH = , 6) 0.2 mM 3-OH = , 7) 0.4 mM 3-OH = . Semen samples were subjected to cryopreservation in French straws and glycerol as a cryoprotectant. In the frozen thawed semen, sperm motility parameters by CASA system and sperm membrane integrity, acrosome status, mitochondrial activity, DNA fragmentation, early apoptosis with capacitation, and LPO were assessed using flow cytometry just after thawing (0 h) and 4 h post thaw. Results reveal significant increase in the proportion of live spermatozoa with undamaged acrosomes in the FL 0.1 and 3-OH = 0.2 groups at 0 h post thaw. At this time point, 3-OH = 0.1 significantly reduced the DNA fragmentation index (DFI) compared to the FL 0.1 and 0.2 groups. However, after the next 4 h, 3-OH = 0.4 exhibited the lowest (P < 0.05) DFI compared to FL 0.2 and 3-OH = 0.1. Additionally, 3-OH = 0.4 showed the highest (P < 0.05) proportion of non apoptotic and non capacitated spermatozoa compared to FL 0.1 0 h post-thaw. Simultaneously, the same group demonstrated significant reduction in apoptotic and capacitated sperm cells, at 0 h and 4 h post-thaw. Moreover, 3-OH = at 0.1 (0 h and 4 h) and 0.2 mM (4 h) significantly enhances the proportion of live sperm without LPO post thaw. Whitin the FL groups, only 0.4 FL significantly increased the percentage of live sperm without LPO. No significant effect of the tested substances was observed on sperm motility, cell membrane integrity, or mitochondrial activity. These findings highlight the promising role of flavone and 3-hydroxyflavone in enhancing sperm resilience during cryopreservation, suggesting their protective function against acrosome damages, capacitation, apoptosis and lipid peroxidation.

The impact of mitochondrial impairments on sperm function and male fertility: a systematic review

BACKGROUND

Besides adenine triphosphate (ATP) production for sustaining motility, the mitochondria of sperm also host other critical cellular functions during germ cell development and fertilization including calcium homeostasis, generation of reactive oxygen species (ROS), apoptosis, and in some cases steroid hormone biosynthesis. Normal mitochondrial membrane potential with optimal mitochondrial performance is essential for sperm motility, capacitation, acrosome reaction, and DNA integrity.

RESULTS

Defects in the sperm mitochondrial function can severely harm the fertility potential of males. The role of sperm mitochondria in fertilization and its final fate after fertilization is still controversial. Here, we review the current knowledge on human sperm mitochondria characteristics and their physiological and pathological conditions, paying special attention to improvements in assistant reproductive technology and available treatments to ameliorate male infertility.

CONCLUSION

Although mitochondrial variants associated with male infertility have potential clinical use, research is limited. Further understanding is needed to determine how these characteristics lead to adverse pregnancy outcomes and affect male fertility potential.

Poor Sperm Chromatin Condensation Is Associated with Cryopreservation-Induced DNA Fragmentation and Cell Death in Human Spermatozoa

Background/Objectives: Semen cryopreservation is routinely performed in fertility clinics for a variety of reasons, including fertility preservation and storage of donor sperm, yet the freeze-thaw process leads to cellular damage via ice crystal formation, osmotic shock, and supraphysiological levels of oxidative stress. Sperm resistance to damage during the freeze-thaw process varies widely, yet the intrinsic factors associated with sperm cryotolerance are largely unknown. The study aimed to investigate whether poor chromatin condensation renders sperm vulnerable to DNA fragmentation and cell death induced by the freeze-thaw process. Methods: Participants (n = 51) from the general community who met the inclusion criteria collected a semen sample after 3-8 days of abstinence. Neat semen samples underwent traditional semen analysis, aniline blue (AB)-eosin staining for chromatin condensation, the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay for DNA fragmentation, and the Annexin V assay for apoptosis/necrosis, prior to being cryopreserved using the liquid nitrogen vapour method and stored at -196 °C. Stored samples were later thawed at room temperature and processed using density gradient centrifugation. Motile sperm concentration, DNA fragmentation and apoptosis/necrosis were analysed in post-thaw samples. Results: As indicated by a significant interaction effect in linear mixed models, an increased proportion of AB-positive sperm in the pre-freeze sample exacerbated the adverse effect of freezing on sperm DNA fragmentation (p = 0.004), late apoptosis (p = 0.007), and necrosis (p = 0.007). AB-staining was positively correlated with all three parameters in the post-thaw sample (all rs ≥ 0.424, all p < 0.01) and remained significant after adjusting for neat sperm concentration (all partial rs ≥ 0.493, all p < 0.01). Similarly, AB-staining was significantly correlated with the percentage point change in sperm DNA fragmentation (rs = 0.366, p = 0.014) and necrosis (rs = 0.403, p = 0.009), both of which remained significant after adjusting for neat sperm concentration (both partial rs ≥ 0.404, both p < 0.01), and borderline significantly correlated with percentage point change in late apoptosis (rs = 0.307, p = 0.051). Conclusions: Sperm with poorly condensed chromatin may be more susceptible to cellular damage during the freeze-thaw process, independent of pre-freeze sperm concentration. These findings may help to explain the intrinsic variation in sperm resistance to cryodamage within and between individuals that is poorly understood.

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.

Impact of various cryo-preservation steps on sperm rheotaxis and sperm kinematics in bull

Semen cryopreservation is an important tool that has massively contributed to the progression of animal reproduction, especially in cattle. Nonetheless, a large part of the sperm population suffers from cryostress and loses fertility during the process. Although bovine semen cryopreservation is more advanced than any other species, there are still some missing links in the technology knowledge. The aim of the current study was to detect the effect of cryopreservation steps on sperm rheotaxis. Semen samples were collected from sex bulls and analyzed inside a microfluidic platform with CASA after each step of cryopreservation, including control, dilution with yolk citrate, cryoprotectant addition, and cooling or freezing. The results showed that positive rheotaxis % (PR) was not affected during cryopreservation. On the contrary, the sperm kinematics of the positive rheotactic sperm undergo significant changes, as velocity parameters (VCL, VSL, and VAP) were lower in both the cryoprotectant adding and cooling/freezing steps than in the control and yolk citrate dilution steps, while progression parameters (LIN and BCF) were higher in the cryoprotectant and cooling/freezing steps than in the control and yolk citrate dilution steps. Beside these results, an interesting phenomenon of sperm backward positive rheotaxis has been observed. The results of backward sperm rheotaxis samples revealed a significant decrease in PR%, while all sperm kinematics except BCF were significantly higher than normal rheotaxis samples. Based on these results, we conclude that positive rheotactic sperm cells are the elite of the sperm population; however, they still get some sublethal cryodamage, as shown by alterations in sperm kinematics. We also suggest that the sperm-positive rheotaxis mechanism is a mixture of an active and passive process rather than a passive physical one.

Sperm freezing damage: the role of regulated cell death

Substantial progress in research on sperm cryopreservation has occurred since the twentieth century, especially focusing on improving sperm freezing procedures and optimizing semen extenders. However, the cellular biological mechanisms of sperm freezing damage are still unclear, which greatly restricts the promotion and development of sperm cryopreservation. An essential component of sperm freezing damage is the occurrence of cell death. Considering the existence of multiple types of cell death pathways, this review discusses connections between characteristics of regulated cell death (e.g., apoptosis and ferroptosis), and accidental cell death (e.g., intracellular ice crystals) with sperm freezing damage and explores possible future research directions in this field.

Effect of fumigation height and time on cryopreservation of ram semen

The cooling rate is a crucial factor in the process of freezing semen, influencing the overall freezing effectiveness. The height and time of fumigation can significantly impact the rate of cooling. Appropriate cooling rates can help minimize the formation of ice crystals in spermatozoa and reduce potential damage to them. Therefore, the aim of this study was to evaluate the effect of different fumigation heights and time for the cryopreservation of Hu ram semen. Experiments I-IV assessed the effect of semen cryopreservation by testing the post-thawed spermatozoa total motility (TM), progressive motility (PM) and kinetic parameters fumigated at distances of 2, 4, 6 and 8 cm for durations of 5, 10, 15 and 20 min, respectively. Based on the results of experiments I to IV, experiment V evaluated the effect of semen cryopreservation by testing the post-thawed spermatozoa TM, PM, kinetic parameters, plasma membrane integrity, acrosome integrity and reactive oxygen species (ROS) level fumigated at distances of 2, 4, 6 and 8 cm for duration of 20 min. The results indicated that fumigation at 2 cm for 20 min significantly (P < 0.05) improved spermatozoa TM, PM, mean angular displacement (MAD), plasma membrane integrity and acrosome integrity compared to other groups. Additionally, it significantly (P < 0.05) reduced spermatozoa ROS level compared to the 6 and 8 cm groups. In conclusion, fumigation for 20 min at a distance of 2 cm from the liquid nitrogen surface is the most suitable cooling method for the cryopreservation of Hu ram semen.

Timing of semen cryopreservation: before or after processing?

Objective

Seminal cryopreservation causes significant damage to the sperm; therefore, different methods of cryopreservation have been studied. The aim of the study was to compare the effects of density gradient processing and washing/centrifugation with seminal plasma removal for cryopreservation in semen parameters.

Methods

Seminal samples of 26 normozoospermic patients were divided into 3 parts: with seminal plasma; after washing/centrifugation; and after selection through density gradient. The samples were cryopreserved for at least two weeks. Motility, sperm count, morphology and viability were evaluated before cryopreservation and after thawing.

Results

Density gradient processing selected motile and viable sperm with normal morphology in fresh samples (p<0.05). Cryopreservation negatively affected all sperm parameters regardless of the processing performed, and even if the sperm recovery was lower in the density gradient after the thawing, progressive motility, total motility, viability and morphology remained higher (p<0.05).

Conclusion

Cryopreservation significantly compromises sperm parameters (motility, morphology, viability). In normozoospermic patients, the density gradients select better quality spermatozoa compared to other processing methods; this benefit was kept after thawing.

L-Proline: A Promising Tool for Boosting Cryotolerance and Fertilizing Ability of Cryopreserved Sperm in Animals

Sperm cryopreservation technology significantly contributes to the safeguarding of genetic resources, particularly for endangered species, and supports the use of artificial insemination in domestic animals. Therefore, cryopreservation can negatively affect sperm health and function leading to reduce the freezing ability and fertility potential. Therefore, it is essential to prioritize the improvement of cryotolerance in cryopreserved sperm to enhance reproductive efficiency and ensure sustainability in livestock herds. The main reason for sperm dysfunction after thawing may be related to the excessive amount of oxidative stress (OS) produced during cryopreservation. Scientists have different ways for counteracting this OS including the use of plant extracts, enzymes, minerals, anti-freezing proteins, and amino acids. Recently, one such amino acid is L-proline (LP), which has multiple roles such as osmotic and OS defense, nitrogen, and carbon metabolism, as well as cell survival and signaling. LP has been found in seminal plasma and has recently been added to the freezing extender to improve the various post-thaw parameters of sperm. This improvement is related to the ability of LP to reduce the OS, sustain the plasma membrane and to act as an osmoregulatory agent. Moreover, LP can suppress cell apoptosis by modulating intracellular redox in sperm. This review addresses the ongoing research on the addition of L-proline as an osmoregulatory agent in freezing extenders to increase the cryotolerance of animal spermatozoa to freeze-thaw.

Evaluation of the effects of hydroxytyrosol on human sperm parameters during cryopreservation

Human sperm cryopreservation is a routine procedure in assisted reproductive technology, but it has detrimental effects on different sperm parameters due to oxidative stress. Our objective was to assess the impacts of hydroxytyrosol (HT), as an antioxidant, on human sperm parameters following cryopreservation. In the first phase, 20 normal human semen samples were cryopreserved using the rapid freezing method with different concentrations of HT including 0, 50, 100, 150, and 200 μg/mL. In the second phase, 20 normal semen samples were collected and cryopreserved with 50 and 100 μg/mL HT. The beneficial effects of HT were determined by evaluation of motility (computer-assisted sperm analysis; CASA), viability (Eosin-nigrosine stain), DNA integrity (sperm chromatic dispersion test, SCD), reactive oxygen species (DCF and DHE staining by flowcytometry) lipid peroxidation (malondialdehyde, MDA test) and mitochondrial membrane potential (JC1 staining by flowcytometry) of sperm after cryopreservation. After thawing, sperm motility had an increasing trend in 50 and 100 μg/mL HT groups in comparison with other groups, althought the difference was not significant. However, sperm viability was significantly increased at 50 and 100 μg/mL HT. Our data also showed that sperm DNA fragmentation was significantly decreased after thawing at 100 μg/mL in comparison with 0 and 50 μg/mL HT. However, the level of intracellular reactive oxygen species, lipid peroxidation and mitochondrial membrane potential were not significantly different between groups. Our results showed that HT may have protective effects on the viability and DNA integrity of human sperm during the freezing-thawing process.

The characterization of CellROX™ probes could be a crucial factor in ram sperm quality assessment

Several authors have demonstrated that low levels of reactive oxygen species (ROS) are necessary for the physiological functions of sperm, such as capacitation, hyperactivation, acrosomal reaction and fertilization. However, high levels of ROS are associated with oxidative stress and detrimental effects on fertility. Consequently, deep characterization of ROS presence using different fluorescent probes could be crucial. In this sense, the study of intracellular ROS localization and the relationships between ROS and other conventional parameters could improve the characterization of sperm quality for semen preservation protocols in rams. In this work, a multiparametric study was carried out by analyzing four experimental groups of ram sperm with different initial qualities: fresh semen (from both breeding and nonbreeding seasons), frozen-thawed semen and, a positive control group treated with hydrogen peroxide (300 μM) as a marker of extreme damage. Sperm analyses, including viability, apoptosis, lipid peroxidation, motility and kinetic parameters, were applied to compare several experimental groups with different sperm qualities. After that, the signals from two different ROS probes: CellROX™ Deep Red (CRDR) and Green (CRG), were examined by flow cytometry (percentage of cells that express ROS) and fluorescence microscopy (intracellular ROS location). Comparing conventional parameters, fresh samples from the breeding season showed the highest sperm quality, while the positive control samples showed the worst sperm quality. Concerning the ROS probes, the CRDR levels were higher in fresh samples from the breeding season than in the positive control and cryopreserved samples. Surprisingly, CRG presented its highest level (P < 0.05) in the positive control group treated with peroxide by flow cytometry. CRDR and CRG presented opposite labeling patterns that were corroborated by fluorescence microscopy, which determined that the probes localized in different parts of sperm. CRDR was found in the sperm mitochondrial region, while CRG was observed in the cell nucleus, suggesting that ROS localization is an important factor. Finally, our study indicates that CRDR is correlated with proper viability and sperm motility, and could be associated with high mitochondrial activity, while CRG is associated with sperm damage.

The Use of Non-Apoptotic Sperm Selected by Magnetic Activated Cell Sorting (MACS) to Enhance Reproductive Outcomes: What the Evidence Says

Sperm selection of the most competent sperm is a promising way to enhance reproductive outcomes. Apoptosis is the programmed cell death process to maintain tissue homeostasis, and MACS sperm selection of non-apoptotic cells enables the removal of apoptotic sperm from an ejaculate, thus leaving the non-apoptotic available to be microinjected, but given the associated costs of adding these sperm selection steps to the routine practice, there is a need for a careful examination of the literature available to answer questions such as who can benefit from this MACS, how significant this improvement is, and how robust the evidence and data available supporting this choice are. Thus, the aim of this narrative review was to objectively evaluate the available evidence regarding the potential benefits of the use of MACS. From the literature, there are controversial results since its implementation as an in vitro fertilization add-on, and this may be explained in part by the low quality of the evidence available, wrong designs, or even inadequate statistical analyses. We concluded that the benefits of adding MACS are unclear, and further methodologically sound research on specific populations is much needed before offering it clinically.

New strategies for germ cell cryopreservation: Cryoinjury modulation

Cryopreservation is an option for the preservation of pre- or post-pubertal female or male fertility. This technique not only is beneficial for human clinical applications, but also plays a crucial role in the breeding of livestock and endangered species. Unfortunately, frozen germ cells, including oocytes, sperm, embryos, and spermatogonial stem cells, are subject to cryoinjury. As a result, various cryoprotective agents and freezing techniques have been developed to mitigate this damage. Despite extensive research aimed at reducing apoptotic cell death during freezing, a low survival rate and impaired cell function are still observed after freeze-thawing. In recent decades, several cell death pathways other than apoptosis have been identified. However, the relationship between these pathways and cryoinjury is not yet fully understood, although necroptosis and autophagy appear to be linked to cryoinjury. Therefore, gaining a deeper understanding of the molecular mechanisms of cryoinjury could aid in the development of new strategies to enhance the effectiveness of the freezing of reproductive tissues. In this review, we focus on the pathways through which cryoinjury leads to cell death and propose novel approaches to enhance freezing efficacy based on signaling molecules.

Sperm DNA Fragmentation after Cryopreservation and Sperm Selection Has No Implications for Clinical Pregnancies and Live Births after Intrauterine Insemination with Donor Sperm

Intrauterine insemination with donor sperm (IUI-D) requires multiple in vitro manipulations such as sperm selection and cryopreservation during which spermatozoa may be exposed to oxidative stress (OS) and other insults that may produce potential damage including sperm DNA fragmentation (SDF). High levels of SDF, referring to damage or breaks in the genetic material of sperm cells, are linked to an increased risk of reproductive failure. This retrospective, observational study set out to evaluate whether SDF assessment could predict clinical outcome in an IUI-D program, where sperm donors are selected on strict conventional semen parameters. A total of 18 donors and 106 recipients were matched for IUI-D. Out of 429 cycles, 100 (23.3%) resulted in clinical pregnancy. We counted 78 live births (18.2% of cycles), while 20 pregnancies ended in miscarriage (4.7% of cycles), 1 in extra-uterine pregnancy and 1 in stillbirth. Female age significantly influenced clinical pregnancy and miscarriage rates. SDF increased after cryopreservation (26.3 ± 14.5%; p < 0.001) and more so after post-thaw density gradient (34.9 ± 22.1%; p = 0.04) without affecting clinical pregnancy (OR [95% CI] 1.01 [0.99; 1.02]; p = 0.27), live birth (1.00 [0.99; 1.02]; p = 0.72) and miscarriage rates (1.02 [1.00; 1.05]; p = 0.08). The implications of our findings extend to a better selection of sperm donors and a better sperm preparation technique tailored to the donor semen's properties in order to maximize the chances of a favorable treatment outcome.

Melatonin Protects Bovine Spermatozoa by Reinforcing Their Antioxidant Defenses

Cryopreserved semen is widely used in assisted reproductive techniques. Post-thawing spermatozoa endure oxidative stress due to the high levels of reactive oxygen and nitrogen species, which are produced during the freezing/thawing process, and the depletion of antioxidants. To counteract this depletion, supplementation of sperm preparation medium with antioxidants has been widely applied. Melatonin is a hormone with diverse biological roles and a potent antioxidant, with an ameliorative effect on spermatozoa. In the present study, we assessed the effect of melatonin on thawed bovine spermatozoa during their handling. Cryopreserved bovine spermatozoa were thawed and incubated for 60 min in the presence or absence of 100 μΜ melatonin. Also, the effect of melatonin was assessed on spermatozoa further challenged by the addition of 100 μΜ hydrogen peroxide. Spermatozoa were evaluated in terms of kinematic parameters (CASA), viability (trypan blue staining) and antioxidant capacity (glutathione and NBT assay, determination of iNOS levels by Western blot analysis). In the presence of melatonin, spermatozoa presented better kinematic parameters, as the percentage of motile and rapid spermatozoa was higher in the melatonin group. They also presented higher viability and antioxidant status, as determined by the increased cellular glutathione levels and the decreased iNOS protein levels.

Lactobacillus plantarum secretions may exert a cryoprotective effect on human sperm motility: A prospective in vitro study

BACKGROUND

Semen cryopreservation is a widely used procedure for fertility preservation, despite some level of cryodamage that may occur in spermatozoa after thawing. However, there is some evidence that lactobacilli, one of the bacteria found in semen, might benefit sperm quality.

OBJECTIVES

This study aims to determine whether the addition of Lactobacillus plantarum secretions to sperm freezing medium has an impact on sperm motility, morphology, and DNA fragmentation.

MATERIALS AND METHODS

This is a prospective auto-controlled study. It was conducted on 30 raw semen samples from 30 infertile men attending a fertility center for semen analysis. Before freezing, all the samples were analyzed for motility, morphology, and DNA fragmentation percentages. Each sample was then divided equally into three aliquots. Cryopreservation was performed on each aliquot using one of the following three media: without Lactobacillus plantarum secretions (control group) or with 107 or 108 colony-forming units/mL Lactobacillus plantarum secretions. Sperm motility, morphology, and DNA integrity were evaluated after the cryopreservation media were added and after semen thawing.

RESULTS

The results of this study indicated that after thawing, no statistically significant decrease in progressive motility and non-progressive percentages were detected in the sperm freezing medium supplemented with 108 colony-forming units/mL Lactobacillus plantarum secretions than the fresh raw semen. Moreover, multivariate linear regression model analyses showed that the progressive motility (p = 0.02), non-progressive motility (p = 0.016), and non-motile spermatozoa (p = 0.012) percentages were significantly decreased in the freezing medium (without Lactobacillus plantarum secretions) compared to the fresh raw semen.

DISCUSSION AND CONCLUSION

To the best of our knowledge, this is the first study showing that Lactobacillus plantarum secretions had a cryoprotective effect on sperm motility when added to the sperm freezing medium. Furthermore, Lactobacillus plantarum secretions were found to protect sperm DNA integrity more effectively than the freezing medium without Lactobacillus plantarum secretions in non-normozoospermia group. Cryopreservation procedures must therefore be optimized to minimize any iatrogenically induced sperm DNA damage, given the correlation between sperm DNA damage and increased mutation loads in progeny.

Improvement of post-thaw quality and fertilizing ability of bull spermatozoa using Rho kinase inhibitor in freezing extender

In this study, it was hypothesized that the addition of an appropriate concentration of Y-27632 (a ROCK inhibitor) to the freezing extender prevents cryopreservation-induced apoptosis and improves embryonic development after in vitro fertilization (IVF). Semen samples were collected from five fertile Simmental bulls using an artificial vagina twice a week for 4 weeks. Selected samples were pooled and diluted with Tris-egg-yolk-glycerol (TEYG) extender containing different concentrations of Y-27632 (0, 10, 20, 30, and 40 μM) and then frozen in liquid nitrogen. After thawing, computer-assisted semen analysis (CASA), plasma membrane integrity, and acrosome intactness were evaluated in terms of morphological abnormalities, intracellular generation of reactive oxygen species (ROS), DNA fragmentation, phosphatidylserine (PS) externalization, and apoptotic-related gene expression. Finally, groups of frozen and thawed spermatozoa were used for bovine oocyte IVF. The results show that the semen extender at a concentration of 20 μM Y-27632 effectively improved total motility (TM), curvilinear velocity (VCL), as well as the plasma membrane and acrosome integrity compared to the control group (p < 0.05). Intracellular ROS levels were significantly (p < 0.05) lower in samples treated with 30 μM Y-27632 compared to the control specimen. Furthermore, supplementation of the semen extender with 20 μM Y-27632 resulted in more viable spermatozoa compared with the control group (p < 0.05). According to qRT-PCR results, the expression levels of BAX and CASPASE-9 genes in samples treated with 30 μM Y-27632 were significantly downregulated, while the expression of BCL2 was increased compared to the control (p < 0.05). The results of IVF demonstrated that the treatment of frozen-thawed spermatozoa with 20 μM Y-27632 increased blastocyst rates compared to the control group (p < 0.05). In conclusion, the addition of 20 μM Y-27632 into the freezing extender can improve the functionality and the fertilizing capacity of frozen spermatozoa due to its antioxidative and anti-apoptotic properties.

Cellular and Molecular Consequences of Stallion Sperm Cryopreservation: Recent Approaches to Improve Sperm Survival

Cryopreservation of stallion semen does not achieve the post-thaw quality or fertility results observed in other species like cattle. There are many reasons for this, but the membrane composition and intracellular changes in stallion sperm predispose them to low resistance to the cooling, freezing, and subsequent thawing process. Damage to the sperm results from different processes activated during cryopreservation, including oxidative stress, apoptosis, and structural modifications in the sperm membrane that increase the deleterious effect on sperm. In addition, significant individual variability is observed among stallions in the ability of sperm to survive the freeze-thaw process. Recent advances in genomics, transcriptomics, proteomics, metabolomics, and epigenetics are making it possible to advance our understanding of the cellular and molecular processes involved in the cryopreservation process, opening new possibilities for improvement. This review addresses the ongoing research on stallion semen cryopreservation, focusing on the cellular and molecular consequences of this procedure in stallions and discusses the new tools currently available to increase the tolerance of equine spermatozoa to freeze-thaw.

A comprehensive review and update on human fertility cryopreservation methods and tools

The broad conceptualization of fertility preservation and restoration has become already a major concern in the modern western world since a large number of individuals often face it in the everyday life. Driven by different health conditions and/or social reasons, a variety of patients currently rely on routinely and non-routinely applied assisted reproductive technologies, and mostly on the possibility to cryopreserve gametes and/or gonadal tissues for expanding their reproductive lifespan. This review embraces the data present in human-focused literature regarding the up-to-date methodologies and tools contemporarily applied in IVF laboratories' clinical setting of the oocyte, sperm, and embryo cryopreservation and explores the latest news and issues related to the optimization of methods used in ovarian and testicular tissue cryopreservation.

A new role of H89: Reduces capacitation-like changes through inhibition of cholesterol efflux, calcium influx, and proteins tyrosine phosphorylation during sperm cryopreservation in buffalo

It is a known fact that cryopreservation initiates premature capacitation in spermatozoa during the cryopreservation process. Protein tyrosine phosphorylation is a landmark of cascade reaction accountable for capacitation or capacitation-like changes in spermatozoa. Therefore, our hypothesis was to test an inhibitor (H89) that reversibly inhibits the cascade reaction responsible for capacitation during the cryopreservation process but does not hamper normal capacitation and fertilizing ability of sperm. For this, sixteen ejaculates were collected from Murrah buffalo bulls (n = 4). Each ejaculate was divided into four equal aliquots and diluted in an egg yolk-based semen dilutor supplemented with 0, 2, 10, and 30 μM concentrations of H89 and cryopreserved. Interestingly, H89 reduces cholesterol efflux from spermatozoa and protects spermatozoa from membrane damage during the cryopreservation process. H89 did not prevent lipid peroxidation of the sperm membrane. H89 reduced intracellular calcium concentration in spermatozoa in a dose-dependent manner, but tyrosine phosphorylation reduction was observed in the 2 and 10 μM H89 groups. The CTC assay revealed that the percentage of uncapacitated spermatozoa in different treatment groups increases in a dose-dependent manner. In the in vitro capacitation medium, the effect of H89 is abolished and spermatozoa underwent normal capacitation, but H89-treated spermatozoa attached to zona pellucida in large numbers compared to untreated spermatozoa. In conclusion, H89 does not only inhibit tyrosine phosphorylation of spermatozoa but it reduces cholesterol efflux and calcium influx, and ultimately reduces capacitation-like changes during the cryopreservation process.

Effect of Pre-Incubation of Cryopreserved Sperm with either Kisspeptin or Glutathione to Mitigate Freeze-Thaw Damage

Background

Sperm cryopreservation reduces sperm quality. Kisspeptin (KP) has beneficial effects on sperm functions. This study compares the effect of KP and Glutathione (GSH) on mitigating the detrimental effects of the freeze-thaw cycle on sperm.

Methods

An experimental study was conducted in Birjand (Iran) during 2018-2020. Thirty normal swim-up semen samples were treated with Ham's F10 medium (negative control), 1 mM GSH (positive control), or KP (10 µM) for 30 min before freezing. The motility, acrosome reaction, capacitation, and DNA quality of the frozen-thawed sperms were assessed according to the WHO guidelines. Statistical analysis was performed using paired t test, one-way analysis of variance, and least significant difference.

Results

Pre-incubation with KP significantly increased the percentage of sperm motility (34.00±6.7, P=0.003) compared to the control (20.44±7.4) and GSH-treated (31.25±12.2) aliquots. The frequency of non-capacitated spermatozoa was significantly higher in the KP-treated group (98.73%) than in the control (96.46%) and GSH-treated (96.49%) aliquots (P<0.001). The percentage of acrosome-intact spermatozoa in the KP-treated group (77.44%) was significantly higher than the control (74.3%) and GSH-treated (74.54%) groups (P<0.001). The sperm frequency with normal histone in the KP-treated group (51.86%) and with normal protamine (65.39%) was significantly higher than the controls (P=0.001 and P=0.002, respectively). The percentage of TUNEL-positive sperm was significantly lower in the KP-treated group (9.09±2.71) than both GSH-treated (11.22±2.73) and control (11.31±2.2) groups (both P=0.002).

Conclusion

Pre-incubation with KP protects sperm motility and DNA integrity from the detrimental effect of the freeze-thaw cycle. KP is suitable as a pre-treatment to control sperm quality during freezing-thawing.

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.

Beneficial effects of trehalose and gentiobiose on human sperm cryopreservation

The protection of human sperm during cryopreservation is of great importance to infertility. Recent studies have shown that this area is still a long way from its ultimate aim of maintaining the maximum viability of sperm in cryopreservation. The present study used trehalose and gentiobiose to prepare the human sperm freezing medium during the freezing-thawing. The freezing medium of sperm was prepared with these sugars, and the sperm were then cryopreserved. The viable cells, sperm motility parameters, sperm morphology, membrane integrity, apoptosis, acrosome integrity, DNA fragmentation, mitochondrial membrane potential, reactive oxygen radicals, and malondialdehyde concentration was evaluated using standard protocols. A higher percentage of the total and progressive motility, rate of viable sperm, cell membrane integrity, DNA and acrosome integrity, and mitochondrial membrane potential were observed in the two frozen treatment groups compared to the frozen control. The cells had less abnormal morphology due to treatment with the new freezing medium than the frozen control. The higher malondialdehyde and DNA fragmentation were significantly observed in the two frozen treatment groups than in the frozen control. According to the results of this study, the use of trehalose and gentiobiose in the sperm freezing medium is a suitable strategy for sperm freezing to improve its motion and cellular parameters.

Coping with Oxidative Stress in Reproductive Pathophysiology and Assisted Reproduction: Melatonin as an Emerging Therapeutical Tool

Infertility is an increasing global public health concern with socio-psychological implications for affected couples. Remarkable advances in reproductive medicine have led to successful treatments such as assisted reproductive techniques (ART). However, the search for new therapeutic tools to improve ART success rates has become a research hotspot. In the last few years, pineal indolamine melatonin has been investigated for its powerful antioxidant properties and its role in reproductive physiology. It is considered a promising therapeutical agent to counteract the detrimental effects associated with oxidative stress in fertility treatments. The aim of the present narrative review was to summarize the current state of the art on the importance of melatonin in reproductive physiology and to provide a critical evaluation of the data available encompassing basic, translational and clinical studies on its potential use in ART to improve fertility success rates.

Cryopreservation of Yak Semen: A Comprehensive Review

An urgent need to boost the sustainability and efficiency of animal production exists, owing to the growing global population. Enhancing the global fertility of animals, especially cattle, is essential to ameliorate this issue. Artificial insemination and sperm cryopreservation have a considerable and favorable influence on the quantity and quality of the cattle produced. Sperm cryopreservation is crucial for livestock production because it promotes and accelerates genetic diversity and the worldwide dispersion of animals with enhanced genetics. Owing to the importance of cryobiology in reproductive technologies, researchers are developing new approaches, and they are testing cryoprotectant drugs to enhance sperm cryosurvival. However, the viability of sperm after freezing is low and widely varies across breeding yaks. These faults are crucial because they impede advances in reproductive biotechnology and the study of mammalian gametes at a fundamental level. Using chemicals, researchers have developed and enhanced various extenders with varying degrees of efficiency to reduce cryodamage and oxidative stress. In this article, we review the cryopreservation of yak semen, the development of extenders, the difficulties faced during cryopreservation, and the evaluation of semen quality using various methodologies. This review might be helpful for researchers exploring semen cryopreservation in the future, as demand for enhanced cryopreservation exists to boost the post-thaw viability and fertility of sperm.

The freezability of Mediterranean buffalo sperm is associated with lysine succinylation and lipid metabolism

Semen cryopreservation is used for the propagation of variety among species and domestic breeding. Mitochondria are implicated in sperm freezability, and their proteins are prone to succinylation, but the relationship between sperm freezability and mitochondrial protein succinylation is unclear. In this study, six bulls were classified as having good or poor freezability ejaculates (GFE or PFE, each 3 bulls). The fresh sperm mitochondrial membrane potential (MMP) and pan succinylation level of the two groups were first detected. Then the lysine succinylome and fatty acid content of the two groups were analyzed using label-free LC-MS/MS and GC-MS/MS in multiple reaction monitoring (MRM) modes, respectively. The results indicated that the GFE sperm had significantly higher MMPs than the PFE group (p < 0.05). A total of 1393 succinylation sites corresponding to 426 proteins were assessed and 5 succinylated peptides of the GFE group were markedly upregulated, while 3 were significantly downregulated (FC > 2.0 - < 0.5 and p-value < 0.05) when compared to the PFE group. Forty-six succinylated proteins were identified to have consistent presence/absence expression. The upregulated succinylated proteins in the GFE sperm were enriched in lipid metabolic processes. A total of 31 fatty acids were further subjected to quantitative analysis of which 23 including arachidic (C20:0), linolenic (C18:3n3), and docosahexaenoic acids (C22:6n3) were decreased in GFE sperm when compared with PFE (p < 0.05). These results suggest that lysine succinylation can potentially influence the sperm freezability of Mediterranean buffaloes through mitochondrial lipid metabolism. This novel study provides our understanding of sperm succinylation and the molecular basis for the mechanism of sperm freezability.

Advances in sperm cryopreservation in farm animals: Cattle, horse, pig and sheep

Sperm cryopreservation is one of the most important procedures in the development of biotechnologies for assisted reproduction. In some farm animals, the use of cryopreserved sperm has so many benefits for which relevance has become more evident in recent decades. Values for post-thaw sperm quality, however, are variable among species and within individuals of the same species. There is no standardized methodology for each of the stages of the cryopreservation procedure (andrological examination, semen collection, dilution, centrifugation, resuspension of the pellet with the freezing medium, packaging, freezing and post-thaw sperm evaluation), which also contributes to differences among studies. Cryotolerance markers of sperm and seminal plasma (SP) have been evaluated for prediction of ejaculate freezability. In addition, in previous research, there has been a focus on supplementing cryopreservation media with different substances, such as enzymatic and non-enzymatic antioxidants. In most studies, inclusion of these substances have led to improved post-thaw sperm quality and fertilizing capacity as a result of minimizing the adverse effects on sperm structure and function. Another approach is the use of different cryoprotectants. The aim with this review article is to provide an update on sperm cryopreservation in farm animals. The main detrimental effects of cryopreservation are described, including the negative repercussion on reproductive performance. Furthermore, the potential use of molecular biomarkers to predict sperm cryotolerance is discussed, as well as the addition of substances that can mitigate the harmful impact of freezing and thawing on sperm.

Biomolecular Pathways of Cryoinjuries in Low-Temperature Storage for Mammalian Specimens

Low-temperature preservation could effectively extend in vitro storage of biological materials due to delayed or suspended cellular metabolism and decaying as illustrated by the Arrhenius model. It is widely used as an enabling technology for a variety of biomedical applications such as cell therapeutics, assisted reproductive technologies, organ transplantation, and mRNA medicine. Although the technology to minimize cryoinjuries of mammalian specimens during preservation has been advanced substantially over past decades, mammalian specimens still suffer cryoinjuries under low-temperature conditions. Particularly, the molecular mechanisms underlying cryoinjuries are still evasive, hindering further improvement and development of preservation technologies. In this paper, we systematically recapitulate the molecular cascades of cellular injuries induced by cryopreservation, including apoptosis, necroptosis, ischemia-reperfusion injury (IRI). Therefore, this study not only summarizes the impact of low-temperature preservations on preserved cells and organs on the molecular level, but also provides a molecular basis to reduce cryoinjuries for future exploration of biopreservation methods, materials, and devices.

An evidence of Humanin-like peptide and Humanin mediated cryosurvival of spermatozoa in buffalo bulls

Buffalo spermatozoa are vulnerable to cryo-injuries due to inherent deficiency of endogenous antioxidants, high polyunsaturated fatty acids (PUFA) content in plasma membrane and low cholesterol/phospholipid (C/P) ratio. Humanin is a potent cytoprotective agent that protects the cells against oxidative stress and apoptosis. The present study was designed to establish the presence of Humanin in buffalo and effect of Humanin supplementation on freezability of buffalo spermatozoa. Indirect immunofluorescence test revealed presence of Humanin in ejaculated and epididymal spermatozoa, and, elongated spermatids and interstitial space in the testicular tissue section. Humanin levels in seminal plasma were significantly and positively correlated with sperm concentration and individual progressive motility (IPM) in good (n = 22; IPM >70%) and poor (n = 10; IPM <50%) quality ejaculates. For supplementation studies, a total of 24 ejaculates (IPM ≥70%) were collected and each ejaculate was then divided into four aliquots. First aliquot was diluted with egg yolk-tris-glycerol (EYTG) extender without Humanin and served as control group (Group I). Rest three aliquots were diluted with extender containing 2 (Group II), 5 (Group III) and 10 μM Humanin (Group IV), respectively. Semen was cryopreserved using standard protocol and evaluated at pre-freeze for lipid peroxidation (LPO) and post-thaw stages for spermatozoa kinematics, LPO, mitochondrial membrane potential (MMP), capacitation, apoptotic status and DNA integrity. The treatment group that showed best results (5 μM) was compared with control group for in vitro fertility assessment by homologous zona binding assay. The LPO levels were lower (p < 0.05) in 5 and 10 μM Humanin supplemented group. The MMP and DNA integrity were higher (p < 0.05) in 5 μM group than other groups. F-pattern was higher (p < 0.05) and B-pattern was lower (p < 0.05) in 5 and 10 μM Humanin supplemented groups. Lower apoptotic and higher viable spermatozoa (p < 0.05) were observed in 5 μM Humanin group. The mean number of spermatozoa bound to zona pellucida was higher (p < 0.05) in 5 μM Humanin treated group than the control group. The study established the presence of Humanin in buffalo spermatozoa and seminal plasma for very first time and concluded that Humanin supplementation at 5 μM concentration improves the freezability and in vitro fertility of buffalo spermatozoa.

Restoring Sperm Quality Post-Cryopreservation Using Mitochondrial-Targeted Compounds

While critical for male fertility preservation, cryopreservation damage reduces sperm quality and fertilization potential. This study investigated whether the addition of mitochondrial-targeted, antioxidant compounds, also known as Mitochondrial activators, to the cryopreservation medium could protect sperm quality during cryopreservation. For this, semen samples from men undergoing IVF/ICSI treatment, which were donated for research, underwent cryopreservation in the absence or presence of BGP-15, MitoQ and L-carnitine. Fresh semen and thawed sperm samples from the same participant were analyzed for indicators of sperm quality: sperm viability, kinetics, mitochondrial reactive oxygen species (ROS) levels, Mitochondrial Membrane Potential (MMP) and DNA damage. Cryopreservation significantly reduced sperm viability and motility and predicted mucous penetration. BGP-15, MitoQ and L-carnitine improved sperm motility, whilst the addition of L-Carnitine prevented the loss of sperm viability during cryopreservation. Both BGP-15 and L-carnitine reduced sperm DNA oxidative damage, but only BGP-15 significantly reduced DNA fragmentation. More importantly, BGP-15 increased sperm predictive mucous penetration and MMP and reduced DNA oxidation. Our results show that the addition of BGP-15 or L-carnitine to the cryopreservation medium improves sperm quality post-thawing, highlighting the potential of mitochondrial antioxidants to improve long-term fertility preservation in males.

Effect of Sperm Cryopreservation in Farm Animals Using Nanotechnology

Sperm cryopreservation is one of the sublime biotechnologies for assisted reproduction. In recent decades, there has been an increasing trend in the use of preserved semen. Post-thaw semen quality and values vary among animals of the same species. Similarly, there are species-specific variations in sperm morphology, i.e., sperm head, kinetic properties, plasma membrane integrity, and freezability. Similarly, the viability of sperm varies in the female reproductive tract, i.e., from a few hours (in cattle) to several days (in chicken). Various steps of sperm cryopreservation, i.e., male health examination, semen collection, dilution, semen centrifugation, pre- and post-thaw semen quality evaluation, lack standardized methodology, that result in differences in opinions. Assisted reproductive technologies (ART), including sperm preservation, are not applied to the same extent in commercial poultry species as in mammalian species for management and economic reasons. Sperm preservation requires a reduction in physiological metabolism by extending the viable duration of the gametes. Physiologically and morphologically, spermatozoa are unique in structure and function to deliver paternal DNA and activate oocytes after fertilization. Variations in semen and sperm composition account for better handling of semen, which can aid in improved fertility. This review aims to provide an update on sperm cryopreservation in farm animals.

Mitochondria-Targeted Compounds to Assess and Improve Human Sperm Function

Significance: Currently 10%-15% of couples in reproductive age face infertility issues. More importantly, male factor contributes to 50% of these cases (either alone or in combination with female causes). Among various reasons, impaired sperm function is the main cause for male infertility. Furthermore, mitochondrial dysfunction and oxidative stress due to increased reactive oxygen species (ROS) production, particularly of mitochondrial origin, are believed to be the main contributors. Recent Advances: Mitochondrial dysfunction, particularly due to increased ROS production, has often been linked to impaired sperm function/quality. For decades, different methods and approaches have been developed to assess mitochondrial features that might correlate with sperm functionality. This connection is now completely accepted, with mitochondrial functionality assessment used more commonly as a readout of sperm functionality. More recently, mitochondria-targeted compounds are on the frontline for both assessment and therapeutic approaches. Critical Issues: In this review, we summarize the current methods for assessing key mitochondrial parameters known to reflect sperm quality as well as therapeutic strategies using mitochondria-targeted antioxidants aiming to improve sperm function in various situations, particularly after sperm cryopreservation. Future Directions: Although more systematic research is needed, mitochondria-targeted compounds definitely represent a promising tool to assess as well as to protect and improve sperm function. Antioxid. Redox Signal. 37, 451-480.

Sperm cryopreservation and DNA methylation: possible implications for ART success and the health of offspring

Despite the beneficial effects of sperm cryopreservation, increased reactive oxygen species (ROS) production during this process can affect spermatozoon structure and function. Moreover, ROS production is associated with elevated DNA damage and alterations in DNA methylation. There is little information about the effects of cryopreservation on epigenetic modulation in sperm and the health of children born with frozen spermatozoa. Considering the potential consequences of cryopreservation in ART-conceived children, it is necessary to assure that cryopreservation does not modify sperm DNA methylation status. This review summarizes reports on epigenetic modifications of spermatozoa during cryopreservation and the probable effects of this process on offspring health. Contradictory results have reported the influence of sperm cryopreservation on DNA methylation in imprinted genes. Multiclinical studies with larger sample sizes under the same conditions of cryopreservation and DNA methylation analysis are needed to make any definitive conclusion about the effect of the cryopreservation process on sperm DNA methylation.

Determining the Optimal Dosage of Lecithin Nanoliposome in Rooster Semen Freezing Medium and Fertility Potential

Introduction: Lecithin nanoliposome (nano-LPO), with its cryoprotective properties, is considered to enhance the performance of a traditional semen cryoprotectant. Objective: To determine the optimal dose of lecithin nano-LPO added to the rooster semen extender. Materials and Methods: Semen samples collected weekly from eight broiler breeder roosters were mixed and aliquoted into five equal subsamples, during the five successive weeks. The subsamples were then diluted with a semen extender containing 0%, 0.5%, 1%, 1.5%, or 2% of lecithin nano-LPO. Post-thawed semen quality attributes, including sperm motility and velocity parameters, plasma membrane functionality, mitochondrial membrane potential (MMP), apoptosis-like changes, and fertility potential, were evaluated. Results: Total motility and velocity parameters, including curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity μm/s (VAP), straightness (STR), linearity (LIN), lateral head displacement (ALH), and wobble (WOB) were quadratically (p < 0.01) influenced by graded levels of lecithin nano-LPO, such that the highest values were obtained when 1% of lecithin nano-LPO was used. Treatments had no significant effect on plasma membrane functionality; however, MMP (p < 0.08) and percentages of live and dead spermatozoa (p < 0.05) quadratically responded to increasing levels of lecithin nano-LPO, where the best outcome was found when about 1% of lecithin nano-LPO was used in the semen extender. The percentage of apoptotic spermatozoa cubically responded to increasing levels of lecithin nano-LPO (p ≤ 0.07). No significant trend of fertility rate was found in response to addition of lecithin nano-LPO levels. Conclusions: Supplementing an extender with 1.10% of lecithin nano-LPO is shown to be the optimal dose associated with the most improvement in post-thawed rooster sperm velocity measurements.