The protective effects of melatonin against cryopreservation-induced oxidative stress in human sperm

Quercetin in semen extender curtails reactive oxygen and nitrogen species and improves functional attributes of cryopreserved buck semen

Cryopreservation of goat spermatozoa is challenging due to several factors, including one of the most essential, i.e., oxidative stress. It is particularly essential in goat semen due to its scanty ejaculate volume and high sperm concentration. This leaves a narrow sperm-to-seminal plasma ratio owing to marginal antioxidant support; moreover, semen extension further dilutes the antioxidant level, leading to an imbalance of oxidant-antioxidant equilibrium. The present study aimed to evaluate the effect of quercetin on curtailing oxidative stress and its reflection on the post-thaw survivability and membrane integrity of goat spermatozoa. For this study, six bucks were selected. Six ejaculates from each buck totaling 36 ejaculates were collected, which were then split into five parts; furthermore, each part was added with a semen extender having a particular concentration of additive. Group C without quercetin and T1 containing Vitamin E at 3 mmol/mL were considered the control and positive control respectively, whereas T2, T3, and T4 contain 10, 20, and 30 μmol/mL of Quercetin respectively. The final sperm concentration of each group was kept at 200 × 106 spermatozoa/mL. All groups were subjected to equilibration at 4 °C for 4 h, then filled in French mini (0.25 mL) straws, followed by sealing and cryopreservation. Samples after 72 h of cryopreservation were subjected to evaluation of plasma membrane integrity and viability through staining, acrosomal integrity, and mitochondrial membrane activity through flow cytometry. Evaluation of sperm kinematics as well as the oxidant-antioxidant status of sperm (ROS and nitric oxide) and seminal plasma (SOD, CAT, GPx, FRAP, and lipid peroxidation through MDA estimation) were also carried out. Quercetin, when supplemented at 20 μmol/mL in buck semen extender, significantly (p < 0.01) improved cryopreserved sperm functions in terms of plasma membrane integrity, viability, acrosomal integrity, mitochondrial membrane activity, and sperm kinematics of buck semen. Similarly, Quercetin supplementation at 20 μmol/mL significantly reduced reactive oxygen and nitrogen species (RONS) in sperm and improved the antioxidant status of seminal plasma, which was indicated by reduced oxidative damage and improved the antioxidant status of buck semen. In conclusion, Quercetin at 20 μmol/mL reduced oxidative stress, improved semen antioxidant status, and improved sperm membranes integrity and kinematics.

Effect of type and concentration of antioxidant on sperm motility, viability, and DNA integrity of climbing perch Anabas testudineus Bloch, 1792 (Pisces: Anabantidae) post-cryopreservation

Sperm quality is preserved through the crucial involvement of antioxidants, which play a vital role in minimizing the occurrence of reactive oxygen species (ROS) during the cryopreservation process. The suitability of the type and concentration of antioxidants are species-dependent, and this study is crucial in order to improve the quality of the climbing perch sperm post-cryopreservation. Therefore, this study aimed to determine the best type and concentration of antioxidants for cryopreservation of climbing perch Anabas testudineus sperm. To achieve this, 6 types of antioxidants, namely, ascorbic acid, beta-carotene, glutathione, butylated hydroxytoluene (BHT), myo-inositol, and alpha-tocopherol, with inclusion of a control were tested in 3 replications at three concentration levels of 0 mg/L (control), 20 mg/L, 40 mg/L, and 60 mg/L. Sperm was diluted in a glucose-base extender at a ratio of 1:60 (sperm: glucose base), then 10 % DMSO and 5 % egg yolk was added before cryopreservation for two weeks. The results showed that the type and concentration of antioxidants had a significant effect on the motility and viability of cryopreserved climbing perch sperm (P < 0.05), where the best results for ascorbic acid, beta-carotene, glutathione, myo-inositol, and alpha-tocopherol were obtained at a concentration of 60 mg/L, while BHT was at a concentration of 20 mg/L. The best results for glutathione, myo-inositol, and alpha-tocopherol were significantly different from other treatments, while the best results for ascorbic acid and beta-carotene (60 mg/L) were not significantly different from the 40 mg/L concentration, while the best results for BHT were not significantly different from the control treatments. Therefore, the best concentration of glutathione, myo-inositol, and alpha-tocopherol was 60 mg/L, while for ascorbic acid and beta-carotene it was 40 mg/L, and BHT was not recommended. DNA integrity analysis indicated the absence of fragmentation in all samples, including fresh, control, and treated sperm. Based on practical and economic considerations, myo-inositol at 60 mg/L was recommended for cryopreservation of climbing perch A. testudineus sperm.

Effect of melatonin on cryopreservation of Beijing you chicken (gallus gallus) spermatozoa

Beijing You Chicken, a valuable local chicken breed from Beijing, China, was once listed as an endangered breed. From the point of view of conservation, the preservation of this breed is an important task for the local researchers. Semen cryopreservation is a popular method to maintain valuable species. However, during cryopreservation, semen is susceptible to oxidative damage. Melatonin is a potent antioxidant and free radical scavenger, so it has been selected to improve the efficiency of sperm cryopreservation. In this study, the chicken semen was treated with different concentrations of melatonin in the cryopreservation solution. The results showed that melatonin at concentrations of 10-3 M and 10-5 M significantly improved sperm progressive motility and total motility, respectively, compared to the control (P < 0.05). Melatonin at 10-3 M also significantly improved the plasma membrane and acrosome integrity of spermatozoa compared to the control. The mechanisms are that melatonin significantly reduces the level of ROS and preserves sperm mitochondrial membrane potential. Most importantly, the melatonin-treated cryopreserved chicken sperm after artificial insemination significantly increased the hatching rate of chicks compared to the control (p < 0.05). The results show that melatonin has a positive effect on the quality of the cryopreserved spermatozoa. These results provide the theoretical and practical basis for using melatonin to improve Beijing You Chicken conservation, and they may also be applicable to poultry as a whole.

Granulocyte-Macrophage Colony-Stimulating Factor Cytokine Addition After the Freeze-Thawing Process Improves Human Sperm Motility and Vitality in Asthenoteratozoospermia Patients

The cryopreservation-thawing process of spermatozoa cells has negative impacts on their structure, function, and fertility parameters, which are known as cryoinjury. Asthenozoospermia patients are more susceptible to cryoinjury. Granulocyte-macrophage colony-stimulating factor (GM-CSF) increases sperm glucose uptake via the induction of glucose transporters, resulting in increased sperm motility. This study aimed to investigate the efficiency of GM-CSF supplementation of the cryopreservation media for semen samples of asthenoteratozoospermia patients. The study was carried out on 20 semen samples from infertile men referred to diagnosing semen analysis. To avoid subjective bias, two main sperm motility parameters, including velocity along the curvilinear path and velocity along the straight-line path were considered by the computer-assisted sperm analysis system. Afterward, each semen sample was divided into three equal aliquots and randomly assigned to one of the following groups: group I (control, freezing media only), group II (+GM-CSF, freezing medium supplemented with 2 μL/mL GM-CSF), or group III (GM-CSF added after thawing and washing). Following semen thawing, standard parameters, mitochondrial membrane potential (MMP), and the DNA Fragmentation Index were analyzed. Total sperm motility (progressive and non-progressive) improved significantly in group III samples after a 30-minute incubation with GM-CSF compared with the control group (26.5% ± 3.1% vs. 17.51% ± 2.59%). However, no differences in progressive motility or sperm morphology were found among the three thawed samples. The percentage of vitality was significantly higher in group III compared with the other two groups (28.38% ± 3.4% vs. 22.4% ± 3.08% and 22.14% ± 2.77%, respectively) (p < 0.05). JC-1 levels (a marker of MMP) were not significantly different between the examined groups (44.95% ± 8.26% vs. 36.61% ± 6.95% vs. 46.67% ± 7.7%, for control, group II, and group III, respectively) (p > 0.05). GM-CSF may be advantageous as an additive after freezing, improving total motility and viability after 30 minutes of post-thaw incubation; however, when supplied to the freezing media before cryopreservation, it is unable to protect against cryoinjury.

The Effects of Silymarin Supplementation on Post-Thawed Human Sperm Functional Parameters

This study investigated the effect of silymarin on human sperm quality during cryopreservation. Samples were collected from 20 normospermic individuals, and each sample was divided into different concentrations of silymarin comprising the following groups: (0, 20, 100, 500, and 1000 μg/mL silymarin). Sperm quality parameters, such as plasma membrane integrity, mitochondrial membrane potential, acrosomal membrane integrity, and caspase 3 were estimated. Silymarin concentrations of 100-500 μg/mL significantly increased motility, plasma membrane integrity, and mitochondrial activity compared with the frozen control group. Acrosomal integrity was increased in the 1000 μg/mL silymarin group. Moreover, 20 and 100 μg/mL concentrations significantly decreased the percentage of caspase 3. The addition of silymarin antioxidant to the frozen medium reduced damage in the sperm after freezing and thawing. This is the first study that showed silymarin can be useful in cryopreservation of human sperm.

The Role of Melatonin to Ameliorate Oxidative Stress in Sperm Cells

It is widely accepted that oxidative stress (OS) coming from a wide variety of causes has detrimental effects on male fertility. Antioxidants could have a significant role in the treatment of male infertility, and the current systematic review on the role of melatonin to ameliorate OS clearly shows that improvement of semen parameters follows melatonin supplementation. Although melatonin has considerable promise, further studies are needed to clarify its ability to preserve or restore semen quality under stress conditions in varied species. The present review examines the actions of melatonin via receptor subtypes and its function in the context of OS across male vertebrates.

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.

Effects of Melatonin and Silymarin on Reactive Oxygen Species, Nitric Oxide Production, and Sperm Viability and Motility during Sperm Freezing in Pigs

Sperm during the freezing and thawing process is damaged by oxidative stress. Thus, its antioxidant scavenger is essential for sperm survival and death in frozen-thawed semen. We used melatonin and silymarin in experiments after the dose-dependent experiment. Our study aimed to identify the effect of melatonin and silymarin on the motility and viability of sperm, reactive oxygen species (ROS), and nitric oxide (NO) production in frozen-thawed boar semen. Melatonin and silymarin were treated alone and cotreated in the fresh boar semen. Boar semen was collected using the gloved-hand method from ten crossbred pigs, and samples were used in the experiments. We evaluated sperm viability using SYBR-14 and PI kit, and ROS and NO production were detected by DCF-DA and DAF-2, respectively. The sperm motility was not significantly different between non-treatment and treatment. ROS and NO production in frozen-thawed sperm were decreased by melatonin and silymarin. Moreover, silymarin significantly reduced NO production more than melatonin. Melatonin and silymarin enhanced the viability of sperm. We suggest that melatonin and silymarin are essential antioxidants in semen cryopreservation for protecting sperm damage and maintaining sperm viability. Melatonin and silymarin may be useful antioxidants in freezing boar sperm.

Human Sperm as an In Vitro Model to Assess the Efficacy of Antioxidant Supplements during Sperm Handling: A Narrative Review

Spermatozoa are highly differentiated cells that produce reactive oxygen species (ROS) due to aerobic metabolism. Below a certain threshold, ROS are important in signal transduction pathways and cellular physiological processes, whereas ROS overproduction damages spermatozoa. Sperm manipulation and preparation protocols during assisted reproductive procedures-for example, cryopreservation-can result in excessive ROS production, exposing these cells to oxidative damage. Thus, antioxidants are a relevant topic in sperm quality. This narrative review focuses on human spermatozoa as an in vitro model to study which antioxidants can be used to supplement media. The review comprises a brief presentation of the human sperm structure, a general overview of the main items of reduction-oxidation homeostasis and the ambivalent relationship between spermatozoa and ROS. The main body of the paper deals with studies in which human sperm have been used as an in vitro model to test antioxidant compounds, including natural extracts. The presence and the synergic effects of different antioxidant molecules could potentially lead to more effective products in vitro and, in the future, in vivo.

Melatonin loaded PLGA nanoparticles effectively ameliorate the in vitro maturation of deteriorated oocytes and the cryoprotective abilities during vitrification process

Almost all cells can be exposed to stress, but oocytes, which are female germ cells, are particularly vulnerable to damage. In this study, melatonin, a well-known antioxidant, was loaded into biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) and delivered to damaged oocytes in order to improve their quality and restoration. Etoposide (ETP)-induced deteriorated oocytes show poor maturity, mitochondrial aggregation, and DNA damage. Treatment of NPs not only reduced DNA damage but also improved mitochondrial stability, as evidenced by increased ATP levels and mitochondrial homogeneity. When melatonin was added to the culture medium at the same concentration as that present in NPs, DNA and mitochondrial repair was insignificant due to the half-life of melatonin, whereas DNA repair in damaged oocytes upon multiple treatments with melatonin was similar to that observed with melatonin-loaded NPs. Next, we evaluated whether the oocytes treated with NPs could have cryoprotective abilities during vitrification/thawing. Vitrified-oocytes were stored at -196 °C for 0.25 h (T1) or 0.5 h (T2). After thawing, live oocytes were subjected to in vitro maturation. The NP-treated group showed maturity similar to the control group (77.8% in T1, 72.7% in T2) and the degree of DNA damage was reduced compared to the ETP-induced group (p < 0.05).

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.

Application of Nanoparticles and Melatonin for Cryopreservation of Gametes and Embryos

Cryopreservation of gametes and embryos, a technique widely applied in human infertility clinics and to preserve desirable genetic traits of livestock, has been developed over 30 years as a component of the artificial insemination process. A number of researchers have conducted studies to reduce cell toxicity during cryopreservation using adjuvants leading to higher gamete and embryo survival rates. Melatonin and Nanoparticles are novel cryoprotectants and recent studies have investigated their properties such as regulating oxidative stresses, lipid peroxidation, and DNA fragmentation in order to protect gametes and embryos during vitrification. This review presented the current status of cryoprotectants and highlights the novel biomaterials such as melatonin and nanoparticles that may improve the survivability of gametes and embryos during this process.

Effect of Different Concentrations of Melatonin on Ram Epididymal Spermatozoa Recovered Post-mortem under Oxidative Stress Conditions and Storage at 4 °C

The current study examines the protective effects of different melatonin concentrations on fresh ram epididymis spermatozoa after post-mortem recovery under normal and oxidative stress conditions and during liquid preservation (4^o C) at different times (24, 48, and 72h). The testes were obtained from a local slaughterhouse during the breeding season. Spermatozoa were isolated from cauda epididymidis. In experiment 1, the effects of adding different concentrations of melatonin (0, 15, 60, and 240 μg/mL) under normal and oxidative stress conditions were evaluated. Fifty μM of hydrogen peroxide was used to induce oxidative stress. Also, in experiment 2, the spermatozoa samples were chilled to 4^o C and stored for 72 h. Sperm total motility, viability, membrane, DNA integrity, and morphological abnormality were evaluated at 0, 24, 48, and 72 h after cooling storage. In experiment 1, melatonin treatment preserved viability increased TAC and SOD activities, and reduced MDA levels compared to control. Also, melatonin reduced the harmful effects of H2O2 under induced oxidative stress. In experiment 2, Melatonin at concentrations of 15 and 60 g/mL greatly increased sperm viability after 3 days of cold storage. Furthermore, it could have a significant protective effect on the motility of cooled sperm. Melatonin supplementation preserved higher sperm membrane integrity at concentrations of 15 and 60μg/mL, DNA integrity at a concentration of 15μg/mL, and abnormality at a concentration of 60μg/mL after 3 days of storage. The results suggest that melatonin can be used to reduce the adverse effects of induced oxidative stress in spermatozoa. Furthermore, ram epididymal spermatozoa could be stored at 4 °C for 72 h when treated with melatonin.

Antioxidant Effect of Melatonin on Proliferation, Apoptosis, and Oxidative Stress Variables in Frozen-Thawed Neonatal Mice Spermatogonial Stem Cells

Cryopreservation of spermatogonial stem cells (SSCs) is an important method to restore and maintain fertility in preadolescent children suffering from cancer. For protection of SSCs from cryoinjury, various antioxidant agents have been used. The aim of this study was to assess the antiapoptotic and antioxidant effects of melatonin in frozen-thawed SSCs. SSCs were isolated from testes of neonatal mice (3-6 days old) and their purities were measured by flow cytometry with promyelocytic leukemia zinc finger protein. After culturing, the cells were frozen in two groups (1) control and (2) melatonin (100 μM) and stored for 1 month. Finally, the cell viability, colonization rate, expression of Bcl-2 and BAX gene, and intracellular reactive oxygen species (ROS) were evaluated after freezing-thawing. Melatonin increased the viability and colonization of SSCs and Bcl-2 gene expression. It also diminished BAX gene expression and intracellular ROS. The results of this study show that melatonin with antioxidant and antiapoptotic effects can be used as an additive for freezing and long-term storage of cells and infertility treatment in the clinic.

Preliminary study of the ameliorative effects of melatonin on cadmium-induced morphological and biochemical alterations in the rat Harderian gland

Herein is reported, for the first time in the rat Harderian gland (HG), the counteractive action of melatonin (Mlt), a well-known antioxidant radical scavenger, on the increased oxidative stress damages induced by a pro-oxidant substance, cadmium (Cd), an environmental pollutant also considered as endocrine disruptor. HG, an infraorbital gland present in almost all terrestrial vertebrates, produces a lipid secretion to lubricate the eyeball, as well as porphyrin/Mlt as light transducers. Moreover, HG is an extra-gonadal source of steroid sex hormones. Via ex vivo experiments lasting for 24 h, we verified the increased lipid peroxidation in Cd-treated glands, producing morphological alteration of the glandular epithelium, as well as an increased porphyrins accumulation. Moreover, Cd also induced a decreased protein level of the steroidogenic enzymes steroidogenic acute regulatory (StAR) and 3βHSD, and an increased mast cell number. Results obtained with Mlt cotreatment demonstrated that it decreased the levels of Cd-induced oxidative damage, with reversal of all the observed modification. Furthermore, the TUNEL assay showed that the increased number of apoptotic cells in Cd-treated HG was counteracted by the contemporaneous Mlt administration. Results confirmed that Mlt treatment restored the levels of two autophagy markers, LC3 and p62, counteracting the autophagy Cd-induced. Interestingly, the positive effects of Mlt alone were highlighted by the decreased rate of lipid peroxidation as compared with the control, confirming its antioxidant action. Combined data further confirmed the antioxidant action of Mlt in counteracting the degeneration provoked by reactive oxygen species (ROS) in the rat HG, a tissue extremely susceptible to oxidative stress condition.

Melatonin in cryopreservation media improves transplantation efficiency of frozen-thawed spermatogonial stem cells into testes of azoospermic mice

Background

Cryostorage of spermatogonial stem cells (SSCs) is an appropriate procedure for long-term storage of SSCs for fertility preservation. However, it causes damage to cellular structures through overproduction of ROS and oxidative stress. In this study, we examined the protective effect of melatonin as a potent antioxidant in the basic freezing medium to establish an optimal cryopreservation method for SSCs.

Methods

SSCs were obtained from the testes of neonatal male mice aged 3–6 days. Then, 100 μM melatonin was added to the basic freezing medium containing DMSO for cryopreservation of SSCs. Viability, apoptosis-related markers (BAX and BCL2), and intracellular ROS generation level were measured in frozen–thawed SSCs before transplantation using the MTT assay, immunocytochemistry, and flow cytometry, respectively. In addition, Western blotting and immunofluorescence were used to evaluate the expression of proliferation (PLZF and GFRα1) and differentiation (Stra8 and SCP3) proteins in frozen–thawed SSCs after transplantation into recipient testes.

Results

The data showed that adding melatonin to the cryopreservation medium markedly increased the viability and reduced intracellular ROS generation and apoptosis (by decreasing BAX and increasing BCL2) in the frozen–thawed SSCs (p < 0.05). The expression levels of proliferation (PLZF and GFRα1) and differentiation (Stra8 and SCP3) proteins and resumption of spermatogenesis from frozen–thawed SSCs followed the same pattern after transplantation.

Conclusions

The results of this study revealed that adding melatonin as an antioxidant to the cryopreservation medium containing DMSO could be a promising strategy for cryopreservation of SSCs to maintain fertility in prepubertal male children who suffer from cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03029-1.

New Insight on the In Vitro Effects of Melatonin in Preserving Human Sperm Quality

Spermatozoa (SPZ) are sensitive to stressful conditions, particularly oxidative stress, which alters their quality; thus, the use of protective molecules as an antioxidant is encouraged. Herein, we used melatonin (MLT) to investigate its in vitro effects on human sperm parameters under conditions of oxidative stress induced by cadmium (Cd). Fifteen human semen samples were divided into control, Cd-treated, MLT-treated, and Cd+MLT-treated groups and analyzed after 30 min, 6 h, and 24 h of exposure. Results showed a time-dependent decrease in SPZ motility, DNA integrity, and increased apoptosis induced by oxidative stress, and these effects were counteracted by MLT co-treatment. Based on these data, we further explored additional parameters just at 24 h. The induced oxidative stress, highlighted by the increased lipid peroxidation, reduced the percentage of SPZ able to undertake acrosome reaction and altered the levels and localization of some protein markers of motility (PREP, RSPH6A), morphology (DAAM1), and acrosome membrane (PTMA, IAM38); all these effects were counteracted by MLT co-treatment. Interestingly, MLT alone was able to ameliorate motility at 30 min of incubation compared to the control, while at 24 h, it prevented the physiological alteration in terms of motility, DNA integrity, and apoptosis. Collectively, the data encourage MLT use as an integrative molecule to ameliorate human gamete quality when compromised by stressful conditions.

The Protective Role of Melatonin in Sperm Cryopreservation of Farm Animals and Human: Lessons for Male Fish Cryopreservation

Simple Summary

In recent years, cryopreservation of fish sperm has been a rapidly evolving technique that contributes both to the improvement of genetic reproduction programs and the proper management of broodstock as well as to ensuring the viability of endangered species. However, this technique can cause significant damage to sperm, making the use of cryoprotectants and antioxidants in cryopreservation solutions imperative. The hormone melatonin has demonstrated positive effects on the cryopreservation of sperm in both farm animals and humans. Therefore, the plethora of research that has been conducted on animals and humans could be expanded to fish cryopreservation, making melatonin potentially a very promising alternative cryoprotectant.

Abstract

Cryopreservation is a technique that offers various advantages, especially in fish, among others, that makes the reproduction of species easier through a constant supply of sperm, synchronization of the gamete availability of both sexes, storage of semen for genetic improvement programs, reduction in the cost by eliminating the need to maintain male broodstock, and conserving the gametes of endangered species. However, freezing and warming procedures for cryopreservation lead to a reduction in the quality and viability of cryopreserved sperm because of oxidative stress. For this reason, the enrichment of extender media with antioxidants is a common method of cryopreservation of the semen of several fish species. Recently, many studies have been published for the protective role of antioxidants and especially of melatonin on male fertility preservation both in farm animals and humans, demonstrating the beneficial effects of melatonin as a sperm cryoprotectant. On the other hand, very few studies were conducted using melatonin as an antioxidant in different male fish species for semen cryopreservation. We conclude that the use of moderate concentrations of melatonin are beneficial to semen preservation, and the mechanisms through which melatonin acts positively on spermatozoa need to be further investigated to establish improvement protocols for cryopreservation in fish species.

An In vitro study on the protective effect of melatonin on human sperm parameters treated by cadmium

Background:

Male infertility account for nearly 50% of infertility cases. Cadmium is regarded as a well-known toxic metal for industrial applications; high amounts of cadmium in the human body can result in chronic toxicity. Melatonin as a free radical scavenger has anti-inflammatory, and even anti-cancer and antiapoptotic functions.

Aim:

In this work, we evaluated the protective effect of melatonin on human sperm parameters treated by cadmium.

Study Setting and Design:

This was an experimental study carried out from May to December 2019.

Materials and Methods:

A total of 41 fresh semen samples were collected from fertile men and were divided into 4 groups: (1) control, (2) sperm +25 Nm cd, (3) sperm +25 nM cd +0.1 mM melatonin,(4) sperm +0.1 mM melatonin treated for 60 min. In all groups, semen analysis was performed for motility, viability and DNA fragmentation index (DFI).

Statistical Analysis:

The groups were compared using the ANOVA test.

Results:

The group treated with cadmium showed a significant decrease in rapid and slow motility, and survival rate compared with the control group (P < 0.05). However, the degree of DFI and sperm with non-progressive motility in the group treated with cadmium had a significant increase compared to the control (P < 0.05). The use of melatonin significantly improved sperm parameters such as motility, survival rate and decreased sperm DFI with non-progressive motility.

Conclusions:

The use of melatonin reduces the amount of cadmium damage in human sperm in vitro.

Endocrine disorders and fertility and pregnancy: An update

It is estimated that more and more couples suffer from fertility and pregnancy maintenance disorders. It is associated with impaired androgen secretion, which is influenced by many factors, ranging from genetic to environmental. It is also important to remember that fertility disorders can also result from abnormal anatomy of the reproductive male and female organ (congenital uterine anomalies - septate, unicornuate, bicornuate uterus; acquired defects of the uterus structure - fibroids, polyps, hypertrophy), disturbed hormonal cycle and obstruction of the fallopian tubes resulting from the presence of adhesions due to inflammation, endometriosis, and surgery, abnormal rhythm of menstrual bleeding, the abnormal concentration of hormones. There are many relationships between the endocrine organs, leading to a chain reaction when one of them fails to function properly. Conditions in which the immune system is involved, including infections and autoimmune diseases, also affect fertility. The form of treatment depends on infertility duration and the patient's age. It includes ovulation stimulation with clomiphene citrate or gonadotropins, metformin use, and weight loss interventions. Since so many different factors affect fertility, it is important to correctly diagnose what is causing the problem and to modify the treatment regimen if necessary. This review describes disturbances in the hormone secretion of individual endocrine organs in the context of fertility and the maintenance of pregnancy.

Melatonin and canthaxanthin enhances sperm viability and protect ram spermatozoa from oxidative stress during liquid storage at 4°C

Antioxidants are used to minimize oxidative stress during liquid semen storage. The main aim of current study was to elucidate effect of supplementing melatonin and canthaxanthin in Tris-based extender could enhance seminal quality of ram at 4°C up to 72 h. A total of 48 ejaculates were collected from breeding Magra rams (n = 8) and were preliminarily subjected for various macroscopic and microscopic semen evaluation tests. These ejaculates were pooled and divided into three equal aliquots. Two aliquots were diluted (1:10) using extender encompassing final concentration of 1mM melatonin and 25 µM canthaxanthin and stored at 4°C. Third aliquot with extender only was kept as control. Structural and functional seminal changes were observed at different time points of preservation. Results revealed that mean values for progressive sperm motility, viability and total antioxidant capacity were significantly higher (p < 0.05) in melatonin group while hypo-osmotic swelling test was significantly (p < 0.05) higher in canthaxanthin group. Total sperm abnormalities and malondialdehyde levels were significantly (p < 0.05) lower in both treatment groups indicating their antioxidant efficacy in protection of spermatozoa from oxidative stress. Results of study indicated that supplementation of these antioxidants to ram semen could be used to enhance storage life of liquid semen at 4°C up to 72 h.

A review of methods for preserving male fertility

Male infertility is responsible for 50% of men's health problems and has always been a concern for personal and social issues. A survey of global statistics suggests an increase in infertility rate as one of the critical issues documented in studies. There are different ways of maintaining fertility in men, depending on their age. In this paper, we review the preservation methods used for fertility treatment in Iran and other countries. Available data were reviewed from Google Scholar, PubMed, Scopus, Web of Science, IranMedex, MEDLIB, IranDoc and Scientific Information Database and searched for articles published up to 2018, using the medical subject heading (MeSH) terms for cryopreservation, sperm, testicular, spermatogonia stem cell, male infertility and/or Iranian and in the world, to provide evidence from evaluation of fertility preservation the methods. Based the search strategy, 274 manuscripts were found. After reviewing the titles, abstracts and manuscripts in their entirety, 119 articles were obtained and selected according to the eligibility criteria. The 85 studies mentioned above were divided into three categories (sperm, testis, and spermatogonia stem cells (SSCs)), and methods of fertility preservation were investigated. Ways to maintain male fertility were different depending on age, and included sperm, testicular, and SSC freezing. The number of studies on testicular tissue and SSCs was low for human samples, and more studies are still needed. Sperm freezing at infertility centres is the top for male fertility preservation.

Effects of Inositol Supplementation in Sperm Extender on the Quality of Cryopreserved Mesopotamian Catfish (Silurus triostegus, H. 1843) Sperm

In this study, the effects of supplemented inositol on sperm extenders were examined on the spermatozoa motility rate and duration, total antioxidant and oxidant status, apoptotic spermatozoa and DNA damage, during the sperm post-thaw process of Mesopotamian Catfish (Silurus triostegus, H. 1843). The semen was frozen in diluents containing different inositol concentrations (5, 10, 20 and 40 mg). Increasing levels of inositol linearly improved the spermatozoa motility rate and duration significantly (p < 0.05). MDA and TOS were linearly decreased, however, TAS and GSH linearly increased (p < 0.05). The increasing inositol levels resulted in a linear and quadratic decrease in DNA damage in the comet assay, 8-hydroxydeoxyguanosine and the determined percentage of apoptotic spermatozoa (p < 0.05). These results suggest that there are many positive effects of the use of supplemental inositol on enhancing sperm cryopreservation efficiency in Silurus triostegus.

Overview on the Antioxidants, Egg Yolk Alternatives, and Mesenchymal Stem Cells and Derivatives Used in Canine Sperm Cryopreservation

Sperm cryopreservation is a widely used assisted reproductive technology for canine species. The long-term storage of dog sperm is effective for the breeding of dogs living far apart, scheduling the time of artificial insemination that suits the female, and preventing diseases of the reproductive tract. However, spermatozoa functions are impaired during the freeze-thaw processes, which may decrease reproductive performance. Numerous attempts have been made to restore such impairments, including the use of cryoprotectants to prevent the damage caused by ice crystal formation, and supplementation of antioxidants to reduce reactive oxygen species generation due to osmotic stress during the procedure. Egg yolk derivatives, antioxidants, and, more recently, mesenchymal stem cells (MSCs) and their derivatives have been proposed in this research field. This review article will summarize the current literature available on the topic.

NADPH Oxidase 5 and Melatonin: Involvement in Ram Sperm Capacitation

Reactive oxygen species (ROS) play an essential role in mammalian sperm capacitation. NADPH oxidase 5 (NOX5) has been described as the main source of ROS production in some mammalian spermatozoa, such as human and equine. On the other hand, melatonin can decrease cellular ROS levels and regulates NOX activity in somatic cells. Therefore, the objectives of this work were (1) to identify NOX5 in ram spermatozoa and analyze its possible changes during in vitro capacitation and (2) to investigate the effect of melatonin on NOX5 expression and localization and on superoxide levels in capacitated ram spermatozoa. Protein bands associated with NOX5 were detected by Western blot analysis. Likewise, indirect immunofluorescence (IIF) revealed six different immunotypes for NOX5, which varied throughout in vitro capacitation. Superoxide (O₂^⋅–), evaluated by DHE/Yo-Pro-1, rose after in vitro capacitation and in the presence of the calcium ionophore A23187 but decreased in the presence of the NOX inhibitor GKT136901. GKT also reduced the percentage of capacitated and acrosome-reacted spermatozoa that had increased during incubation in capacitating conditions. The presence of melatonin at micromolar concentrations avoided the increment in O₂^⋅– and the changes in NOX5 immunotypes provoked by capacitation. In conclusion, NOX5 is present in ram spermatozoa and the changes in its distribution, associated with sperm capacitation, can be prevented by melatonin. To this extent, it could imply that melatonin exerts its antioxidant role, at least in part, by modulating NOX5 activity during ram sperm capacitation.

Cryoprotective Effect of Tretinoin-Loaded Solid Lipid-Core Nanocapsules During Fresh and Freeze/Thaw Media on NMRI Mouse Sperm Parameters, DNA Damage, and Reactive Oxygen Species Production

Due to the induced oxidative stress that exists in sperm freezing/thawing procedures and handling media, the use of exogenous antioxidant agents seems necessary. Drug delivery by nanocarriers has been designed to overcome the limitations of antioxidants, such as high-dose toxicity and short biological half-life. In this study, we tried to investigate the effects of tretinoin-loaded solid lipid core nanocapsules (TTN-SLN) added to freezing/thawing and handling media (in three experimental groups) on sperm motility (total/progressive), viability, DNA fragmentation, and extracellular reactive oxygen species (ROS) levels. Sperm samples from at least 30 adult male NMRI mice were evaluated in this study. The results of experiments 1 and 2 showed that the addition of 0.5 μM TTN-SLN in freezing and thawing medium significantly increased sperm viability and total/progressive motility and decreased DNA fragmentation and extracellular ROS levels (p < 0.05). Adding 0.25 and 0.5 μM of TTN-SLN to the handling medium (experiment 3), increased sperm parameters and decreased DNA fragmentation and extracellular ROS levels significantly (p < 0.05) compared with the control group. Briefly, our results indicate that SLN can deliver the lowest concentrations of tretinoin in a controlled release mechanism into the intracellular space of sperm. Also, high-dose TTN-SLN is safe during freezing/thawing and handling processes of mouse sperm.

Protective Effects of Curcumin on the Outcome of Cryopreservation in Human Sperm

Cryopreservation causes decreased sperm fertility potential due to reactive oxygen species (ROS) production and physical-chemical damage, resulting in reduced sperm viability and motility. The addition of antioxidants to freezing media could protect sperm from cryo-damage, counteracting the harmful effects of ROS. The aim of this study was to assess the effects of curcumin supplementation in freezing medium on preventing cryo-damage in human semen. Semen samples collected from fertile men were cryopreserved in freezing medium supplemented with different concentrations of curcumin (2.5, 5, 10, and 20 μM). After freezing-thawing, sperm parameters, DNA fragmentation, intracellular ROS, and glutathione peroxidase 4 (GPX4) gene expression were evaluated. Supplementation with 20 μM curcumin in freezing medium caused increases in progressive and nonprogressive motility and significant reductions in intracellular ROS and DNA fragmentation in frozen-thawed sperm cells. Following cryopreservation, GPX4 mRNA expression was significantly upregulated in thawed semen supplemented with 20 μM curcumin compared to the control. The results showed that curcumin supplementation in freezing medium was protective against human sperm parameters and sperm DNA, counteracting oxidative damage induced by the freeze-thaw process.

Melatonin improves the effect of cryopreservation on human oocytes by suppressing oxidative stress and maintaining the permeability of the oolemma

Cryopreservation causes cryoinjury to oocytes and impairs their developmental competence. Melatonin (MLT) can improve the effect of cryopreservation in animal oocytes. However, no such studies on human oocytes have been reported. In this study, collected in vitro-matured human oocytes were randomly divided into the following groups: fresh group, MLT-treated cryopreservation (MC) group, and no-MLT-treated cryopreservation (NC) group. After vitrification and warming, viable oocytes from these three groups were assessed for their mitochondrial function, ultrastructure, permeability of oolemma, early apoptosis, developmental competence, and cryotolerance-related gene expression. First, fluorescence staining results revealed that oocytes from the 10^-9  M subgroup showed the lowest intracellular reactive oxygen species and Ca²⁺ levels and highest mitochondrial membrane potential among the MC subgroups (10^-11 , 10^-9 , 10^-7 , and 10^-5  M). In subsequent experiments, oocytes from the 10^-9  M-MC group were observed to maintain the normal ultrastructural features and the permeability of the oolemma. Compared with those of the oocytes in the NC group, the early apoptosis rate significantly decreased (P < .01), whereas both the high-quality cleavage embryo and blastocyst rates significantly increased (both P < .05) in the oocytes of the 10^-9  M-MC group. Finally, single-cell RNA sequencing and immunofluorescence results revealed that aquaporin (AQP) 1/2/11 gene expression and AQP1 protein expression were upregulated in the MC group. Therefore, these results suggest that MLT can improve the effect of cryopreservation on human oocytes by suppressing oxidative stress and maintaining the permeability of the oolemma.

Green tea extract as a cryoprotectant additive to preserve the motility and DNA integrity of human spermatozoa

Cryopreservation impairs sperm quality and functions, including motility and DNA integrity. Antioxidant additives in sperm freezing media have previously brought improvements in postthawed sperm quality. Green tea extract (GTE) is widely considered as an excellent antioxidant, and its beneficial role has been proven in other human cells. This study aims to evaluate the GTE as a potential additive in cryopreservation media of human spermatozoa. In part one, the semen of 20 normozoospermic men was used to optimize the concentration of GTE that maintains sperm motility and DNA integrity against oxidative stress, induced by hydrogen peroxide (H2O2). Spermatozoa were treated with GTE at different concentrations before incubation with H2O2. In part two, the semen of 45 patients was cryopreserved with or without 1.0 ng ml-1 GTE. After 2 weeks, the semen was thawed, and the effect on sperm motility and DNA fragmentation was observed. Our data showed that GTE significantly protected sperm motility and DNA integrity against oxidative stress induced by H2O2when added at a final concentration of 1.0 ng ml-1. We found that the addition of 1.0 ng ml-1 GTE to cryopreservation media significantly increased sperm motility and DNA integrity (both P < 0.05). More interestingly, patients with high sperm DNA damage benefited similarly from the GTE supplementation. However, there was no significant change in the reactive oxygen species (ROS) level. In conclusion, supplementing sperm freezing media with GTE has a significant protective effect on human sperm motility and DNA integrity, which may be of clinical interest.

Pretreatment with melatonin improves ovarian tissue cryopreservation for transplantation

BACKGROUD

Melatonin has anti-inflammatory and antioxidative actions at the mitochondrial level. This indole-containing molecule may protect ovarian grafts during the process of cryopreservation. Therefore, we aimed to determine whether melatonin pretreatment improves rat ovarian graft quality.

METHODS

Twenty-six female rats were allocated to two study groups of thirteen animals each: 1) control group: ovaries cryopreserved using the standard protocol; and 2) melatonin group: ovaries cryopreserved in a medium with melatonin. Ten rats of each group were submitted to 24-h freezing, and whole ovaries autologous and avascular transplantation with retroperitoneal placement. After postoperative (PO) day 15, daily vaginal smears were obtained for estrous cycle characterization. Between PO days 30 and 35, the animals were euthanized and ovarian grafts were recovered for histological and immunohistochemical (Ki-67, cleaved caspase-3, TUNEL, von Willebrand factor, estrogen, and progesterone receptors) analyses. The ovaries of the three remaining rats from each group were studied immediately after thawing to assess the effects of cryopreservation. ANOVA and Tukey's tests were used and the rejection level of the null hypothesis was set at 0.05 or 5% (p < 0.05).

RESULTS

Melatonin promoted faster restart of the estrous cycle and increased the expression of mature follicles, collagen type I, von Willebrand factor, Ki-67, and cleaved caspase-3 on corpora lutea and estrogen receptors in the ovaries as compared to control. There was a reduction in apoptosis by TUNEL on follicles, corpora lutea, and collagen type III.

CONCLUSION

Based on the evaluated parameters, melatonin may promote the quality of ovarian grafts. Reproductive function enhancement should be further studied.

Effect of a Freezing Medium Containing Melatonin on Markers of Pre-meiotic and Post-meiotic Spermatogonial Stem Cells (SSCs) After Transplantation in an Azoospermia Mouse Model Due to Testicular Torsion

Spermatogonial stem cells (SSCs) are essential to the initiation of spermatogenesis. Cryopreservation, long-term maintenance, and auto-transplantation of SSCs could be a new treatment for infertility. The aim of this study was to add melatonin to the basic freezing medium and to evaluate its effect on the efficiency of the thawed SSCs after transplantation into the testicles of azoospermic mice. SSCs were isolated from newborn NMRI mice, and the cells were enriched to assess morphological features. The thawed SSCs were evaluated for survival, apoptosis, and ROS level before transplantation, and the proliferation (MVH and ID4) and differentiation (c-Kit, SCP3, TP1, TP2, and Prm1) markers of SSCs were examined using immunofluorescence, western blot, and quantitative real-time polymerase chain reaction (PCR) after transplantation. It was found that the survival rate of SSCs after thawing was significantly higher in the melatonin group compared with the cryopreservation group containing basic freezing medium, and the rate of apoptosis and level of ROS production also decreased significantly in the cryopreservation group with melatonin (p < 0.05). The expression of proliferation and differentiation markers after transplantation was significantly higher in the cryopreservation group with melatonin compared to the cryopreservation group (p < 0.05). The results suggest that adding melatonin to the basic freezing medium can effectively protect the SSCs by increasing the viability and reducing the ROS production and apoptosis and improve the transplantation efficiency of SSCs after cryopreservation, which will provide a significant suggestion for fertility protection in the clinic.

Melatonin improves the motility and DNA integrity of frozen-thawed ram spermatozoa likely via suppression of mitochondrial superoxide production

The ability of the neurohormone melatonin to ameliorate cryopreservation-induced damage to spermatozoa has been demonstrated in several domestic species. However, it is unclear how these protective effects are conferred, with improvements in sperm quality ambiguously attributed to the general antioxidant activity of melatonin. To further investigate this phenomenon, ram spermatozoa were diluted in cryomedia with and without melatonin (0 [control], 0.1, 1, 10, and 100 μM) and assessed for motility, viability, DNA integrity, mitochondrial superoxide production, lipid peroxidation, and intracellular reactive oxygen species before freezing and after thawing (0, 3, and 6 h post-thaw). Before freezing, supplementation with melatonin at any concentration had no effect on any measure of sperm quality. However, post-thaw, spermatozoa frozen in the presence of any level of melatonin reduced mitochondrial superoxide production of spermatozoa (P < 0.001), decreased the level of sperm DNA fragmentation (P < 0.001), and increased the percentage of motile spermatozoa (P = 0.035). Melatonin supplementation did not influence the relative levels of lipid peroxidation in the sperm membrane, the levels of intracellular reactive oxygen species, or sperm membrane lipid disorder (P > 0.05). There was no difference in the percentage of viable spermatozoa between treatment groups pre- or post-freeze (P > 0.05). These results suggest that, in the ram, melatonin does not protect the quality of cryopreserved spermatozoa through a nondiscerning scavenging of reactive oxygen species as previously suggested. Rather, melatonin appears to specifically reduce mitochondrial superoxide production, altering sperm functionality, as opposed to merely increasing the percentage of live sperm.

Cryoprotective effect of sericin supplementation in freezing and thawing media on the outcome of cryopreservation in human sperm

The destructive effects of sperm cryopreservation result in decreased sperm parameters and their fertilizing ability. Antioxidants supplementation can potentially improve cryopreservation outcomes. In this study, we tried to investigate the effects of sericin supplementation in freezing and thawing media on frozen-thawed human sperm motility, morphology, viability, and DNA fragmentation. In experiment 1, semen samples were collected from 30 healthy fertile men and were cryopreserved in the presence of freezing medium supplemented with different concentrations of sericin (0, 0.5, 1, 2.5, and 5%). The results showed that the addition of 2.5 and 5% sericin in freezing medium significantly increased sperm viability and total motility (A + B) and decreased DNA fragmentation (P < 0.05). In experiment 2, semen samples were collected from 21 fertile men and were cryopreserved in freezing medium without any supplementation for 48 h. Then, the samples were thawed in medium supplemented with different concentrations of sericin (0, 0.5, 1, 2.5, and 5%). The addition of 5% sericin to thawing medium increased the total motility, viability, and decreased DNA fragmentation compared with those in thaws without sericin. In nutshell, the results clearly indicate the feasibility of sericin as an cryoprotective supplement for freezing media in human spermatozoa.

Melatonin can improve viability and functional integrity of cooled and frozen/thawed rabbit spermatozoa

Melatonin is known to protect sperm against freezing-inflicted damage in different domestic species. The aim of the study was to evaluate the effect of supplementation of semen extender with melatonin on the quality and DNA integrity of cooled and frozen/thawed rabbit spermatozoa. We also investigated whether the addition of melatonin to the semen extender could improve the fertility of rabbit does artificially inseminated with frozen/thawed semen. Semen samples collected from eight rabbit bucks were pooled and then diluted in INRA-82 supplemented either with (0.5, 1.0 or 1.5 mM) or without (0.0 mM) melatonin. Diluted semen was cooled at 5°C for 24 hr. For cryopreservation and based on the first experiment's best result, semen samples were diluted in INRA-82 in the presence or absence of 1.0 mM melatonin and then frozen in 0.25 ml straws. Following cooling or thawing, sperm quality and DNA integrity were evaluated. Furthermore, the fertility of frozen/thawed semen was investigated after artificial insemination. Supplementation of semen extender with 1.0 mM melatonin improved (p < .05) motility, viability, membrane and acrosome integrities in cooled semen compared with other groups. Sperm quality and DNA integrity were higher (p < .05) in frozen/thawed semen diluted in 1.0 mM melatonin-supplemented extender than in the control group. Conception and birth rates were higher in does inseminated with 1.0 mM melatonin treated semen compared with the controls. In conclusion, supplementation of semen extender with 1.0 mM melatonin improved the quality of cooled and frozen/thawed rabbit spermatozoa. Melatonin can preserve DNA integrity and enhance the fertility of frozen/thawed rabbit spermatozoa.

Effect of sulforaphane on apoptosis, reactive oxygen species and lipids peroxidation of human sperm during cryopreservation

Sperm cryopreservation is a common procedure to preserve viable sperm for an indefinite period. This procedure has numerous detrimental effects on sperm function due to increased generation of reactive oxygen species (ROS). During cryopreservation, while ROS increases, antioxidant enzymes level decreases. It has been shown that a relationship exist between lower antioxidant levels and infertility. l-Sulforaphane (SFN) is an isothiocyanate in cruciferous vegetables of the brassica class that has potent protective effects against oxidative stress. The purpose of the present study was to evaluate the effects of SFN supplementation during the freeze-thaw process on different parameters of human spermatozoa which can influence sperm fertilizing ability. Samples were collected from 25 healthy men and each sample was divided into three groups: fresh, control (untreated frozen/thawed samples) and treatment (treated frozen/thawed with SFN) groups. Sperm parameters, ROS production (using flow cytometry), plasma membrane integrity (using flow cytometry), Lipid peroxidation (using ELISA) were evaluated. Our results demonstrated that 5 μM SFN improved all parameters of sperm including viability (P < 0.001), motility, and morphology (P < 0.05) after the freeze-thaw process. Furthermore, SFN reduced the levels of intracellular hydrogen peroxide (P < 0.01) and superoxide anion (P < 0.05). Also, SFN significantly increased the percentage of viable sperm cells with the intact plasma membrane (P < 0.001) and decreased the level of lipid peroxidation after the freeze-thaw process (P < 0.01).Our findings showed that spermatozoa treatment with 5 μM SFN before the freeze-thaw process has protective effects against oxidative stress and could decrease the detrimental effects of this process on sperm quality.

Melatonin supplementation improved cryopreserved Thai swamp buffalo semen

The production of reactive oxygen species (ROS) during cryopreservation process impairs the sperm characteristics and fertilizing ability. However, melatonin, an antioxidant, could protect spermatozoa against this cell damage during cryopreservation. Therefore, we attempted to evaluate whether the melatonin supplementing in the semen extender could improve the sperm quality of swamp buffalo during cryopreservation. The semen collected from six swamp buffalo bulls were diluted with tris-citrate egg yolk extender supplementing with 0, 0.1, 0.5, 1.0, 2.0 and 3.0 mM of melatonin. The parameters of sperm viability and motility were evaluated using computer-assisted semen analyser (CASA) after cryopreservation on days 1, 7, 15 and 30. The group supplemented with 1.0 mM melatonin exhibited the higher viability after cryopreservation on days 1, 7, 15 and 30 with 58.346 ± 2.1^a , 57.586 ± 2.0^a , 55.082 ± 1.8^a and 55.714 ± 1.8^a , respectively, and showed the best results of motility parameters. However, higher concentration of melatonin at 3.0 mM impaired all the parameters. In conclusion, the addition of melatonin at 1 mM to semen extender could exert the best protection against sperm damage in swamp buffalo bull during cryopreservation.

Effective cryopreservation protocol for preservation of male primate (Macaca fascicularis) prepubertal fertility

RESEARCH QUESTION

Can specimen types (cells versus tissues) and additive cryoprotectant agents contribute to efficient cryopreservation of primate spermatogonial stem cells (SSC)?

DESIGN

Testicular tissues or cells from four prepubertal monkeys were used in this study. The freezing efficacy of testicular tissue was compared with cell suspensions using conventional freezing media (1.4 mol/l dimethyl sulfoxide [DMSO]) and the efficacy of cryoprotectant additives (1.4 mol/l DMSO combined with trehalose 200 mmol/l, hypotaurine 14 mmol/l, necrostatin-1 50 µmol/l or melatonin 100 µmol/l) was evaluated in testicular tissue freezing.

RESULTS

The survival rate (46.0 ± 4.8% versus 33.7 ± 6.0%; P = 0.0286) and number of recovered cells (5.0 ± 1.5 × 10⁶ cells/g versus 0.7 ± 0.8 × 10⁶ cells/g; P = 0.0286) were significantly higher in frozen tissues than in frozen cell suspensions. After tissue freezing, a higher number of recovered PGP9.5⁺ cells were observed with 200 mmol/l trehalose treatment than in DMSO controls (2.4 ± 0.6 × 10⁶ cells/g versus 1.1 ± 0.3 × 10⁶ cells/g; P = 0.0164). Normal establishment of donor-derived colony was observed in SSC after tissue freezing with 200 mmol/l trehalose.

CONCLUSIONS

Testicular tissue freezing is more effective than single cell suspension freezing for higher recovery of undifferentiated spermatogonia. Moreover, it was verified that slow freezing using 200 mmol/l trehalose, 1.4 mol/l DMSO and 10% KnockOut™ Serum Replacement in Dulbecco's phosphate-buffered saline is an effective cryopreservation protocol for primate testicular tissue.

Melatonin regulates ATP content and fertilising capacity of Onychostoma macrolepis spermatozoa by inhibiting ROS accumulation during semen storage in vitro

Melatonin (MLT) is an efficient antioxidant that protects spermatozoa against damages caused by oxidative stress. In this study, to maintain good function of Onychostoma macrolepis spermatozoa during semen preservation invitro at 4°C, different concentrations of MLT (0.5, 1 and 2μM) were added to the semen. After storage (0, 24, 48 and 72h), 1μM MLT in semen markedly improved sperm quality, as reflected by better plasma membrane integrity, the relative steady level of reactive oxygen species (ROS) and slower rate of decrease in mitochondrial membrane potential. Activated spermatozoa in semen with 1μM MLT had higher kinematic performance (i.e. percentage of motile and progressive spermatozoa and the beat cross frequency; P<0.05) and longer duration of sperm motility (P<0.05) compared with spermatozoa in semen withother MLT concentrations. Furthermore, 1μM MLT maintained higher ATP concentrations in spermatozoa during semen storage and significantly improved the fertilising capacity of spermatozoa after 72h semen storage compared with the other MLT concentrations. To expand wild resources of O. macrolepis, 1μM MLT can be used as a semen additive to maintain better sperm function and enhance sperm fertilising capacity in artificial insemination (AI).

"Emerging role of Novel Seminal Plasma Bio-markers in Male Infertility: A Review"

Male infertility has emerged as an important cause of infertility worldwide. There are many factors affecting male fertility and research is going on to know impact of various factors on sperm functions. Semen analysis is gold standard diagnostic test for male infertility, but it is crude method for estimation of male infertility as seminal composition gets affected by environmental factors, infections, other pathologies, hence, results of semen analysis either becomes normal/ambiguous, leading to failure of diagnosis and delayed treatment. Hence, with need of newer, better tests for assessing male factor infertility, seminal plasma is being tested for biomarkers. Seminal plasma is considered gold mine for male fertility as it contains molecules from male reproductive glands which play important role in sperm function. Study of seminal plasma molecules can give an idea about sperm concentration, motility, morphology and cause of infertility and can serve as biomarkers for male infertility. Present review briefs on some of these novel seminal plasma biomarkers which may play significant role in male fertility and can be used in future for better identification, assessment of infertile males.

METHODOLOGY

Literature from 1985 to 2019 was searched from various databases including PUBMED, SCOPUS, Google Scholar on seminal plasma biomarkers using keywords: "seminal plasma protein biomarkers", "novel seminal plasma markers and male infertility", "hormones in seminal plasma and male infertility", "oxidative stress and male infertility", "Reactive Oxygen Species and sperm DNA", "immunoinfertility".

INCLUSION CRITERIA

All full length original or review articles or abstracts on seminal plasma markers and male infertility published in English language in various peer-reviewed journals were considered.

EXCLUSION CRITERIA

Articles published in languages other than English were excluded from the study.

RESULTS

Seminal plasma is a big reservoir of molecules derived from the various male reproductive glands which can be used as potential biomarkers of male fertility.

CONCLUSION

Hence, seminal plasma biomarkers can be used in future for better assessment of male factor infertility, its causes and may play an important role in management of male factor infertility.

Treatment of rams with melatonin implants in the non-breeding season improves post-thaw sperm progressive motility and DNA integrity

In the Merino ram, it is unclear whether cryopreserved sperm function and fertility is compromised when collected during the non-breeding season, when Merino ewes are seasonally anestrus. It was therefore investigated whether treatment with melatonin could improve sperm function or fertility when semen was collected during the period Merino ewes were seasonally anestrus. There were 16 Merino rams treated or not treated with melatonin implants during the non-breeding season of ewes (September). Ejaculates were collected before melatonin treatment (Week 0), during the period of melatonin release (Week 7) and subsequent breeding season (Week 23). In vitro sperm function was assessed before freezing, and at 0- and 3 -hs post-thaw. Fertility was determined through intrauterine insemination of ewes (n = 966) with frozen-thawed samples, during the breeding season. Compared to Week 0 values, spermatozoa from melatonin-treated rams had greater progressive motility at Week 7 (P = 0.019) and less DNA fragmentation (P = 0.003) at Weeks 7 and 23, whilst spermatozoa from non-treated rams were unchanged during these time-periods. There were no other treatment effects on sperm function or fertility (P > 0.05). In ejaculates collected during Week 23, there were no effects of treatment either before freezing or post-thawing. Sperm from ejaculates collected at Week 23, however, had lesser pre-freezing/post-thawing total motility and resulted in lower pregnancy rates (P < 0.05). It is concluded there are no effects of season on sperm quality or fertility of Merino rams and that melatonin treatment subtly improves quality of spermatozoa following cryopreservation.

Melatonin Inhibits Oxidative Stress and Apoptosis in Cryopreserved Ovarian Tissues via Nrf2/HO-1 Signaling Pathway

In the field of assisted reproductive technology, female fertility preservation, particularly ovarian tissue cryopreservation in adolescent cancer patients, has attracted much attention. Melatonin (MLT) is well known for its antioxidative and anti-apoptotic properties; however, whether it can ameliorate the cryoinjury and inhibit the generation of reactive oxygen species (ROS) in cryopreserved ovarian tissues (OTs) has not yet been reported. Here, we demonstrated that MLT could protect follicular integrity; prevent cell apoptosis; decrease ROS, malondialdehyde (MDA), and nitric oxide (NO) levels; and increase activities of glutathione peroxidases (GSH-Px), glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) in cryopreserved OTs. Furthermore, these effects may be related with the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway, as evidenced by increased mRNA levels of Nrf2 downstream genes, including heme oxygenase-1 (HO-1), glutathione S-transferase M1 (GSTM1), SOD, and CAT. In summary, MLT can not only directly scavenge ROS but also significantly induce the activation of antioxidative enzymes via the Nrf2 signaling pathway, which is a new mechanism underlying the protection effects of MLT on cryopreserved OTs.