Sperm Freezing Research Articles

Sperm signatures of fertility and freezability

Apart from traditional semen examination parameters, there is not yet a set of functional markers for accurate determination of bull fertility and sperm freezability or cryopreservability, which are vital for production of food animals to feed the world. Therefore, reliable biomarkers are needed to objectively analyze semen quality and predict male fertility. Rapid developments in animal biotechnology have led to significant progress in developing science-based solutions for global problems in food animal production. Although andrology studies employing genomic and functional genomics (transcriptomics, proteomics, and metabolomics) approaches have elucidated some molecular aspects of sperm, there is also a need for additional mechanistic studies to ascertain the functional underpinnings. Biomarkers discovered through applying various -omics technologies using sperm from bulls with varying fertility phenotypes are valuable for semen evaluation and fertility prediction.

An evaluation of the population characteristics, semen quality, and utilization status of autologous sperm cryopreservation and fertility preservation in for 662 patients: a 6-year monocentric retrospective study

BackgroundSperm cryopreservation is an effective method of fertility preservation for disease-related and social sperm freezing. In total, 662 subjects (range: 15–65 years-of-age; mean: 33.49 ± 8.79 years-of-age) were included in this study to investigate the population characteristics, semen quality, and usage of autologous sperm preservation patients in Beijing. Of these, 351 were cancer patients (53.02%, 31.14 ± 7.32 years-of-age) and 311 were non-cancer patients (46.98%, 36.14 ± 9.54 years-of-age).ResultsWe found that the number of preservation cases increased steadily from 2015 to 2019; 89.73% of these had a bachelor's degree or above; 54.83%, 41.54%, and 3.63% were single, married, and divorced, respectively. The cases of cancers and oligozoospermia accounted for 71.30% of all patients; therefore, most patients required fertility preservation due to disease. The cancer group had a significantly lower sperm concentration, rate of progressive sperm after the frozen-thawed test, total progressive motility sperm count after the frozen-thawed test, and recovery rate of progressive motile sperm (RRPM) than the non-cancer group (all P < 0.05). Sperm count-related parameters were significantly affected by testicular cancer, while sperm motility-related parameters and RRPM were significantly affected by leukemia. The utilization rate of preserved sperm was 6.34% after 6 to 78 months of follow-up. In terms of fresh or frozen embryo transfer, the clinical pregnancy rate was 56.76% or 50.00%, and the live birth rate was 24.32% or 21.43%, respectively.ConclusionThe need for autologous sperm preservation was dominated by patients with diseases, followed by the need for social sperm freezing. Tumors had a major negative impact on semen quality, and the usage rates of stored semen were at lower level compared to the number of sperm cryopreservation. Medical staff and patients should pay attention to both cognition-action consistency and cost-effectiveness in fertility preservation.

N-acetyl-l-cysteine and alpha lipoic acid are protective supplement on human sperm parameters in cryopreservation of asthenoteratozoospermia patients.

The aim of this study is to evaluate the beneficial effects of N-acetyl-cysteine (NAC), alpha lipoic acid (ALA) and combination of NAC + ALA supplement in freezing medium on Sperm structural and functional in asthenoteratozoospermia patients. Thirty freshly ejaculated semen samples were cryopreserved with sperm freezing medium (SFM) as control group and three group that SFM supplemented with NAC, ALA and their combination NAC+ ALA. The sperm samples were analysed according to WHO. Mitochondrial membrane potential (MMP), acrosome reaction (AR), antioxidant enzymes and DNA fragmentation were assessed using by Rhodamine123, PSA- FITC ELISA and TUNEL staining respectively. Expression level of NRF2 was assessed by real-time PCR assay. NAC and ALA alone significantly improved sperm motility, viability and DNA fragmentation (p< 0.05). MMP increased in NAC and ALA separately (p< 0.05). While did not affect the amount of sperm morphology and AR (p> 0.05). Antioxidant enzymes significantly difference in NAC and ALA groups (p< 0.05). In addition, NAC and ALA groups showed a significantly higher expression of NRF2 gene compared with other groups (p< 0.05). Our results revealed that the ALA and NAC supplements had a protective effect in cryopreservation process on the structural and functional characteristics of sperm.

Effects of extender filtration and egg yolk concentration on canine semen cryopreservation.

The semen cooling and freezing extenders commonly contain the chicken egg yolk (EY) as the main sperm cryoprotectant. Besides its advantages, the EY has large lipoprotein granules that cause several physical and biological interferences. The previous studies have proposed several methods to resolve the problems with the EY-based semen extenders, including mechanical agitation, EY fractionation, replacing the EY with purified EY LDL, and ultrasonication. In the current research, we aimed to evaluate the syringe filtration (220 nm) of an EY-based canine semen freezing extender as a simple and cheap method to remove the EY granules. We also studied the possibility of re-aggregation of EY granules after cooling, freeze/thawing, and lyophilization/rehydration of the filtered extenders. Additionally, we compared the effects of the filtration on lipid profile, turbidity, EY particle size distribution, and osmolality of the EY-based extenders. Next, we examined the effects of filtered extenders containing different levels of EY (5%, 10%, 15%, 20%, and 25%) versus the control extender (20% EY, unfiltered) on post-thaw sperm quality traits. We collected the semen samples from seven clinically healthy mixed-breed adult dogs and pooled them for sperm freezing procedures. Samplings were repeated at least five times, independently. Our results indicated that the syringe filtration could remove the large EY particles and reduce the extender turbidity without affecting the lipid profile of the whole extender solution. The filtered extender supplemented with 25% (v/v) EY led to the best post-thaw canine spermatozoa quality markers. The frozen-thawed spermatozoa evaluations included motility parameters (computer-assisted semen analysis system), membrane and acrosome integrity (hypo-osmotic swelling test, chlortetracycline binding assay), DNA fragmentation (sperm chromatin dispersion assay), membrane lipid peroxidation (MDA levels), apoptosis (Annexin V/propidium iodide assay), and fertility-associated sperm mRNA transcript abundance (protamine 2 and 3). In conclusion, the syringe filtration of the EY-based semen extenders was a simple and cheap method that could effectively remove large EY lipoprotein granules and possibly prevent EY-origin bacterial contamination of the final extender solution. The EY at 25% (v/v) concentration in the filtered extenders resulted in the highest canine spermatozoa cryo-tolerance.

The basis of cell cryopreservation

Cryopreservation (banking) techniques have been known to nature for centuries. Many species of insects, amphibians, fish and even reptiles use natural cryopreservation methods to survive the harsh conditions of winter or to live in extremely cold temperatures. Cryopreservation and dreams of immortality have intrigued humanity for years. The first reports of observing the effects of freezing sperm (stored in snow) date back to 1776. In 1866, Montegazza was the first to suggest a vision completely unimaginable for the time: "a man dying on the battlefield can conceive an heir from sperm frozen and stored at home". The first, at that time still unsuccessful, reports of laboratory freezing of human sperm date back to the 1930s [1]. Finally, mankind "learned" cryopreservation in the middle of the twentieth century, when on October 15, 1949, the article "Revival of spermatozoa after vitrification and dehydration at low temperatures" appeared in print in the Nature journal, summarising the pioneering research of scientists from the National Institute for Medical Research, Mill Hill, London [2]. This concerned the freezing of fowl sperm in the presence of glycerol, ethylene glycol and propylene glycol in such a way that after thawing it was able to fertilise eggs effectively. The subsequent use of dimethyl sulfoxide (DMSO) revolutionised modern cryobiology [3-5]. Thus began the era of cryopreservation, without which today it is difficult to imagine the work of cell biology laboratories, modern animal breeding, or the development of modern medicine.

A novel solution for freezing individual spermatozoa using a right angular cryopiece embedded in a grooved petri dish.

Herein, we introduced a novel individual sperm freezing device named SpermCD, which consists of a right angular cryopiece (RA-Cryopiece, or "C") and a grooved petri dish ("D"). SpermCD allows embryologists to transfer sperm and perform ICSI on the same focal plane. Thirty-five patients underwent single sperm cryopreservation using SpermCD, including four patients with non-obstructive azoospermia (NOA), 14 patients with virtual azoospermia and 17 patients with cryptozoospermia. One hundred and twenty-five cryopreserved spermatozoa from nine patients were thawed on the day of the oocyte retrieval and 121 spermatozoa were found, with a sperm recovery rate of 97.1± 4.6%. Sixty-five MII oocytes from their spouse were injected with thawed sperm. Normal fertilization and high-quality embryo rates were 68.0% ± 33.2% and 24.4% ± 22.2%. Nineteen transplantable embryos were formed after fertilization with frozen sperm, eight of which were transplanted in five couples, resulting in four successful deliveries. SpermCD is a simple and practical individual sperm freezing device.

The impact of Covid-19 on gamete shipping by Australian and New Zealand patients.

Cross-border surrogacy and egg donor arrangements are an increasingly common means to family building. Establishing patterns of use has always been difficult in relation to Australian patients. Accurate data is stymied by lack of documentation of international third-party reproductive care available to Australian authorities. When international travel bans came into effect, it is hypothesised that those planning to use cross-border reproductive care had to rely significantly more on local in vitro fertilisation (IVF) clinics for services such as sperm freezing, embryo creation and gamete release procedures. To quantify and characterise the impact of the Covid-19-related travel ban on international and interstate gamete shipping by Australian IVF clinics. Thirty-one Australian and New Zealand IVF clinics were invited to provide de-identified data on interstate and international gamete export applications from two 12month time periods pre- and during Covid-19-related international travel lockdowns. Seven IVF organisations provided data on: patient age; type of gametes exported; destination country/state; and date gamete release approved. Most gametes (78%) were shipped to another Australian IVF clinic and 22% internationally. Patient-initiated shipping domestically and internationally both showed significant increases when comparing pre- and post-Covid datasets. Of the 21 destination countries reported for international shipments, the US was the commonest (39%), followed by Ukraine (21%) and Canada (9%). The inability of involuntarily infertile patients to travel internationally, rather than halt cross-border reproductive care, has led to a significant increase in the uptake of gamete shipping. The high proportion of internationally shipped gametes going to the US and Ukraine is likely a reflection of the availability of surrogates and donors and more amenable legal frameworks.

Effect of Lactobacillus plantarum secretions on human semen cryopreservation: a prospective auto-controlled in vitro study

Background and Aim: 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 spermatozoa quality. Therefore, this study aims to determine whether the addition of Lactobacillus plantarum (L. plantarum) secretions to a sperm freezing medium has an impact on sperm motility, morphology, and DNA fragmentation.

Albumin (ALB) and protein disulfide isomerase family A member 4 (PDIA4) are novel markers to predict sperm freezability of Erhualian boar

The frozen semen of Erhualian pig can promote the continuous improvement of commercial pigs, but currently, frozen semen fails to satisfy the practical application requirement. Oxidative damage is one of the crucial factors affecting the quality of frozen semen; besides, there are individual differences in boar sperm freezability. Based on the previous analysis of the proteomic differences of Erhualian boar sperm with different freezability, two differentially abundant proteins (DAPs) in boar sperm, albumin (ALB) and protein disulfide isomerase family A member 4 (PDIA4), were selected as the research objects in the current study. It is assumed that redox-related proteins ALB and PDIA4 can be used as markers to predict Erhualian boar sperm freezability. We cryopreserved the semen of 14 Erhualian boars. According to the difference of frozen semen quality, boars with good and poor freezability ejaculates (GFE and PFE, n = 3) were selected respectively. The relative contents of ALB and PDIA4 in GFE and PFE were analyzed by Western blot, and the localization patterns of ALB and PDIA4 in pre-frozen and frozen-thawed sperm were detected by immunofluorescence. The results showed that the abundances of ALB and PDIA4 in GFE were significantly higher than PFE, and there was a significant correlation between the relative contents of ALB and PDIA4 and frozen-thawed sperm quality parameters. Additionally, the freezing process had no effect on the localization patterns of ALB and PDIA4 in spermatozoa. In conclusion, these results suggest that ALB and PDIA4 are related to boar sperm cryotolerance and may be used as novel freezability markers.

Cryopreservation of Roughscale Sole (Clidoderma asperrimum) Sperm: Effects of Cryoprotectant, Diluent, Dilution Ratio, and Thawing Temperature.

Simple SummaryThe roughscale sole, Clidoderma asperrimum, is found in the East and West Seas of Korea, waters north of Hokkaido in Japan, as well as the East China Sea, the East Pacific, and the Canadian Maritimes. In 2021, this fish was categorized as an endangered species. Thus, there is a need to maintain gametes by freezing sperm. This study investigated the impacts of the cryoprotective agent, diluent, dilution ratio, and thawing temperature on the cryopreservation of fish sperm. In this investigation, sperm dilution 1:1 with a mixture of 10% dimethyl sulfoxide + Stein’s solution and thawing at 10 °C provided the most effective DNA damage prevention. These results support the development of a roughscale sole sperm cryopreservation procedure.The roughscale sole, Clidoderma asperrimum is categorized as an endangered species. Sperm freezing is essential for preserving gametes. This study examined the CPA concentration, diluent, dilution ratio, and thawing temperature to design a sperm cryopreservation protocol for roughscale sole. The variables examined included sperm motility and kinematics, cell survival, fertilization, and DNA fragmentation. Sperm motility parameters were assessed via computer-assisted sperm analysis using a CEROS II instrument. Cell survival rate and DNA damage were assessed using the Cell Counting Kit-8 and single-cell gel electrophoresis assay, respectively. Sperm preservation was tested using several CPAs, including ethylene glycol, dimethyl sulfoxide (DMSO), glycerol, propylene glycol, and methanol. The diluents tested were 300 mM sucrose, 300 mM glucose, Stein’s solution, Ringer’s solution, and Hank’s solution. The optimal conditions for sperm cryopreservation were 10% DMSO + Stein’s solution. After thawing, sperm motility was highest with a 1:1 dilution ratio (sperm to CPA + diluent), at 69.20 ± 0.32%; thawing at 10 °C was optimal for post-thaw motility (72.03 ± 0.95%). The highest fertilization rate (40.00 ± 1.22%) was obtained using DMSO. The fresh sperm had the lowest tail DNA, followed by 10% DMSO + Stein’s solution. The developed cryopreservation methods can be used in roughscale sole hatcheries.

The Combined Effect of Melatonin Implant and Removal of Buck Seminal Plasma on Cryopreservation During the Nonbreeding Season.

This study aimed to determine how melatonin (MT) and seminal plasma affected the freezability of buck sperm during the nonbreeding season. Semen was collected from eight bucks before (pre-MT) and after (post-MT) MT application in the nonbreeding season. Individual ejaculates were collected from the bucks, split into two equal groups according to the removal of seminal plasma (SP) (-) or nonremoval of SP (+). For washing, the groups of ejaculates were centrifuged, and the supernatant was separated, SP (-) and SP (+) ejaculates were diluted, then frozen. Semen samples were examined for sperm motility, plasma membrane integrity, defective acrosomes, DNA fragmentation, and mitochondrial membrane function at the native and post-thaw stages. When the general average post-thaw motility (p < 0.01), plasma membrane (p < 0.05), acrosome (p < 0.05), and DNA integrity rates (p < 0.05) and mitochondrial membrane potential (MMP) (p < 0.01) were evaluated, it was seen that MT administration caused a statistically significant improvement. The dramatic effect of nonremoval of seminal plasma on motility and plasma membrane integrity is more clearly observed in individual semen samples frozen in the pre-MT group (p < 0.05). Also, it was observed that removing seminal plasma in the post-MT group caused even milder post-thaw acrosome damage compared with the SP (+) group (p < 0.05). The effect of removing seminal plasma was not observed in terms of DNA integrity and MMP rates in pre- and post-MT groups. As a result, it was concluded that MT application and removal of seminal plasma in the nonbreeding season result in improvement in the freezability of buck semen.

Changes in sperm metabolites of Dezhou donkey after cryopreservation.

Sperm cryopreservation technology has laid the foundation for promoting the popularity of artificial insemination in donkey reproduction, but the freeze-thaw process can cause sperm damage, and the viability of frozen sperm is greatly reduced, resulting in low insemination ability. Sperm metabolites play an important role in the freezing process of spermatozoa and have a major influence on the freezability of spermatozoa. The aim of this study was to explore the differential metabolites in donkey spermatozoa before and after cryopreservation by liquid chromatography-tandem mass spectrometry (LC-MS/MS). We analysed ejaculate samples from male donkeys obtained before and after freezing and identified 1323 metabolites. Compared with fresh sperm (F), the metabolites of cryopreserved sperm (CRY) were significantly changed, and 570 metabolites were significantly different between the two groups (p < .05). Among them, 277 metabolites were higher in frozen sperm, while the opposite was true for 293 metabolites. These metabolites mainly include phospholipids, lysophospholipids and amino acids., most of which are associated with oxidative stress and sperm capacitation. We describe significantly different metabolites before and after freezing that are significantly associated with decreased sperm motility post-freezing and can be used as biomarkers of decreased sperm motility post-freezing.

Seasonal changes in sperm freezability of sex-reversed female rainbow trout

In order to obtain sex-reversed females of Salmonid fish (SRF; neomales, masculinized females) the hormonal treatment of fertilized eggs or larvae is used. As a consequence, masculinized fish possess less-developed testes without functional spermatic ducts. Therefore, the semen of sex-reversed females is generally characterized by low or highly variable quality and reflects testicular rather than ejaculated semen. The aim of our study was to evaluate the alterations in sperm freezability of sex-reversed female rainbow trout during the progression of the spawning season. Sperm concentration, seminal plasma osmolality, semen pH, gonadosomatic index (GSI) and total sperm production (TSP) were monitored in fresh semen. The sperm motility parameters, adenosine triphosphate (ATP) production and sperm viability were examined throughout the spawning season in fresh and frozen/thawed semen. The day of the spawning season did not affect sperm motility of fresh semen. During the equilibration of semen, 2–3-fold increase in the sperm motility compared to fresh semen on each day of the spawning season was recorded. A decrease in the sperm motility after cryopreservation compared to equilibrated semen on each day of the spawning season was recorded. The highest ATP concentrations in fresh semen were noted on the 21st day of the spawning season, whereas in cryopreserved semen, these values were the highest on the 16th and 21st days of the spawning season. The viability of fresh semen did not change during the spawning season; however, the highest sperm viability after cryopreservation was observed between the 11th and 21st days of the spawning season. These results should be taken into account during the planning of cryopreservation of semen of valuable SRF individuals, which will be further used for fertilization of eggs under hatchery conditions.

The Impact of Covid-19 Travel Restrictions on Gamete Shipping from Australian IVF Clinics

Background: Cross-border surrogacy and egg donor arrangements are an increasingly common means to family building. Establishing patterns of use has always been difficult in relation to Australian patients. Accurate data is stymied by lack of documentation of international third-party reproductive care available to Australian authorities. Since Australia’s international travel ban came into effect, it is hypothesised that those planning to use cross-border reproductive care have had to rely significantly more on local IVF clinics for services such as sperm freezing, embryo creation and gamete release procedures. Establishing the increase in gamete shipping as a result of the ban on non-essential travel will improve understanding of the resource impact on Australian IVF laboratories. Such data can also assist policymakers assess the utility of state-based regulations relevant to CBRC. Aim: Quantify and characterise the impact of the Covid-19-related travel ban on Cross-Border Reproductive Care amongst patients of Australian IVF clinics. Method: All Australian IVF clinics were invited to provide de-identified data on interstate and international gamete export applications from two 12 month time periods pre and during Covid-19 related international travel lockdowns. Each dataset included: patient age; type of gametes exported; destination country or state; and date gamete release was approved. Results: Results showed a very significant increase in gamete shipping in the twelve months after Covid-19 travel restrictions were enforced. They illustrate the comparative prevalence of shipping to established and newer destinations during the periods March 2019–February 2020 and June 2020–May 2021. The volume of shipping to the commonest destinations is quantified. Conclusion: The inability of involuntarily infertile patients to travel internationally, rather than halt cross-border reproductive care, has led to a significant increase in update of gamete shipping. This is likely associated with increased utilization of Australian IVF clinics for embryo creation purposes. The high proportion of internationally-shipped gametes going to the US and Ukraine is likely a reflection of the availability of surrogates and donors and the legal frameworks.

Fertility Preservation in Oncological Patients

Background: Lately, attention is given to fertility preservation in reproductive-age patients undergoing oncological treatment. This should become a routine part of today’s assisted reproductive technologies. Methods: Available oncofertility preservation methods, next to their clinical, ethical and legal implications are discussed, within the context of the right to health and its broader aspects as delineated in the 1946 Constitution of the World Health Organization. Results: Possible egg and sperm freezing. as well as ovarian tissue cryopreservation, should always be explained and suggested to fertility-age patients before starting oncological treatment. Sperm, oocyte, and embryo cryopreservation should become standard practice. Conclusions: All ethical, cultural, and moral aspects of fertility preservation in cancer patients are multifaceted and need to rely on principles that are based on widely-accepted guidelines and evidence-based practices. Adequate policy, legislation, and regulations should be agreed upon and implemented.

Mitochondrial Effects, DNA Damage, and Antioxidant Enzyme Activity in Cryopreserved Human Sperm Samples: A Pilot Study

This study aimed to evaluate the impact of a vapor freezing protocol on antioxidant enzyme activity (superoxide dismutase (SOD) and glutathione reductase (GR)), sperm with active mitochondria, DNA damage, and spermatic parameters. Twenty-six semen samples from men undergoing infertility investigation were cryopreserved in liquid nitrogen (LN) vapors and plunged into LN, with (method A) and without (method B) a commercial sperm freezing medium (SFM) and inherent removal with a sperm preparation medium (SPM). Most parameters were assessed before and after freezing, except for SOD and GR activity, which were only assessed after freezing. Although method A promoted better results than method B, the percentage of spermatozoa with active mitochondria, motility, vitality, and normal morphology decreased significantly. DNA damage (determined by comet assay) increased similarly with both methods, but the percentage of spermatozoa with fragmented DNA (by TUNEL assay) remained similar to fresh values when method A was applied. GR activity was higher and SOD activity lower with method A. The addition of SFM coupled with the sperm wash with SPM seems essential to preserve the quality of most of the analyzed spermatic parameters and active mitochondria. The detrimental effects promoted by freezing were shown to depend on the quality of the fresh semen, according to correlation coefficients. Interestingly, thawed samples of both methods shared similar DNA damage. These results highlight the need to find more effective protocols, especially for the freezing of low-quality semen samples.

Evaluation of supplementation of cryopreservation medium with gallic acid as an antioxidant in quality of post-thaw human spermatozoa.

Human sperm cryopreservation is a way to preserve sperm in the clinic. But, the production of reactive oxygen species (ROS) during cryopreservation, has certain negative impacts on the quality of sperm and its reproductive capacity. The goal of this study is to see how sperm cryopreserved in media enriched with gallic acid alter post-thaw morphology, motility, viability, DNA structure, and plasma membrane lipid peroxidation. Four groups were considered for performing this study: (1) Fresh sperm before cryopreservation; (2) cryopreserved control sperm without any supplementation; (3) cryopreserved sperm using freezing media supplemented with 50 μg/ml gallic acid and (4) cryopreserved sperm using freezing media supplemented with 100 μg/ml gallic acid. This study's results indicated that the addition of doses of 50 μg/ml gallic acid to cryopreservation medium significantly improved sperm morphology, motility, vitality, and DNA integrity and reduced DNA fragmentation and lipid peroxidation as compared to the medium without any gallic acid supplementation (p< 0.05); but, the concentration of 100 μg/ml gallic acid had no significant effects on the mentioned sperm parameters (p> 0.05). This study's findings represent the possibility of enhancing sperm characteristics and lowering detrimental effects of ROS on sperm DNA structure during cryopreservation by supplementing sperm freezing medium with gallic acid as a natural antioxidant. Therefore, Gallic acid may help improve the quality and subsequently fertilization potential of cryopreserved human sperm.

Optimizing cryopreservation of sea cucumber (Apostichopus japonicus) sperm using a programmable freezer and computer-assisted sperm analysis

The sea cucumber Apostichopus japonicus has high nutritional, medicinal, and economic value. However, factors such as overexploitation, climate change, and environmental pollution have resulted in serious germplasm degradation in both farmed and wild A. japonicus, and it has been listed as endangered on the IUCN (International Union for Conservation of Nature) Red List of Threatened Species. Cryopreservation is an important method to protect germplasm resources and solve the problem of germplasm degradation. Using a programmable freezer and computer-aided sperm analysis, we comprehensively studied and screened the factors that affect the post-thaw motility of A. japonicus sperm during cryopreservation. Based on our results, we propose the following optimal cryopreservation procedure for A. japonicus sperm: cryo-diluent composition of 12.5% dimethyl sulfoxide and 0.1 mol/L glucose, with filter-sterilized (the filter mesh size: 0.45μm) natural seawater (NSW) as the extender; 1:5 mixing ratio of sperm and cryo-diluent; cooling rate and thawing temperatures of 10°C/min and 20°C, respectively. The post-thaw motility of sperm treated using the optimal procedure was &amp;gt; 65%, the fertilization rate (in the blastocyst stage) was nearly 80%, and the hatching rate (in the early auricularia larva stage) was &amp;gt; 65%. Additionally, frozen sperm that had been cryopreserved for 1 year retained a considerable post-thaw motility and fertilization rate compared to recently cryopreserved sperm. We detected obvious differences in sperm freezability among individual A. japonicus, and cryopreservation caused some damage to the sperm structure. In conclusion, our optimized procedure make large-scale cryopreservation of A. japonicus sperm possible, and our results provide valuable information that could be applied to research and conservation of A. japonicus.

The Effect of Astaxanthin on Motility, Viability, Reactive Oxygen Species, Apoptosis, and Lipid Peroxidation of Human Spermatozoa During the Freezing-Thawing Process.

Cryopreservation of spermatozoa is a general procedure to preserve viable sperm for an indefinite period. Despite the efficiency of sperm cryopreservation, excessive reactive oxygen species (ROS) production during cryopreservation can induce structural and functional changes in spermatozoa. Also, cryopreservation has been shown to decrease the spermatozoa's antioxidant activity inducing them to be more sensitive to damage caused by ROS. Experimental evidence suggests that astaxanthin (AXT) has essential activities such as antioxidant, antibacterial, and antithrombotic properties. Therefore, this study aimed to evaluate the effect of AXT on the sperm quality of healthy men during freezing-thawing. In the first phase, 10 semen samples with different concentrations of AXT (0.0, 0.5, 1, and 2 μM) were cryopreserved to achieve an optimal dose of AXT. Then, motility, viability, and phosphatidylserine (PS) externalization were evaluated. In the second phase, 25 samples were collected and divided into 3 groups: fresh group, control group (untreated frozen-thawed samples), and AXT group (treated frozen-thawed with AXT). Then, samples were cryopreserved in freezing media supplemented with or without the optimal concentration of AXT (1 μM). After thawing, the levels of sperm parameters, including motility (using a computer-assisted sperm analyzer), viability (eosin-nigrosin), early apoptotic change (annexin V/propidium iodide), ROS (flow cytometry), and lipid peroxidation (LPO) (using enzyme-linked immunosorbent assay), were evaluated. Our results showed that the addition of 1 μM AXT to sperm freezing media improved all parameters of sperm motility and viability (p ≤ 0.05). Furthermore, it could reduce the levels of ROS parameters (intracellular hydrogen peroxide and superoxide) compared with the control group (p ≤ 0.05). Also, AXT significantly decreased the level of PS externalization (p ≤ 0.05) and LPO (p ≤ 0.05) after the freezing-thawing process. In conclusion, our findings demonstrated that human semen treatment with 1 μM AXT before the freezing-thawing process has protective effects against oxidative stress and could diminish the destructive effects of this process on sperm quality.

Cryopreservation of Pig Semen Using a Quercetin-Supplemented Freezing Extender.

Reactive oxygen species (ROS) produced during freeze–thaw procedures cause oxidative damage to the sperm, reducing fertility. We aimed to improve the post-thaw quality of pig sperm by quercetin (QRN) supplementation to reduce the cryodamage associated with the freeze–thaw procedure. Four equal aliquots of pooled boar semen were diluted with a freezing extender supplemented with different concentrations of QRN (0, 25, 50, and 100 µM) and then were subjected to cryopreservation in liquid nitrogen. Semen analysis was performed following 7 days of cryopreservation. Results demonstrated that the semen samples supplemented with 50 µM QRN significantly improved the post-thaw sperm quality than those subjected to other supplementations (p < 0.05). Semen samples supplemented with 50 µM QRN showed significantly improved plasma membrane functional integrity (47.5 ± 1.4 vs. 43.1 ± 4.1, 45.3 ± 1.7, and 44.1 ± 1.4) and acrosome integrity (73.6 ± 3.4 vs. 66.3 ± 2.4, 66.7 ± 3.6, and 68.3 ± 32.9) as compared to the control, 25 µM, and 100 µM QRN groups, respectively. The mitochondrial activity of the 50 µM QRN group was greater than control and 25 µM QRN groups (43.0 ± 1.0 vs. 39.1 ± 0.9 and 41.9 ± 1.0) but showed no difference with the 100 µM QRN group. Moreover, the 50 µM QRN group showed a higher sperm number displaced to 1 cm and 3 cm points in the artificial mucus than other groups. Therefore, supplementing the freezing extender with QRN can serve as an effective tool to reduce the magnitude of oxidative damage associated with sperm freezing.