Cryopreservation of human sperm

Evaluation of Dry Ice for Short-Term Storage and Transportation of Frozen Boar Semen

To address the safety problems posed by the transportation of boar semen using LN, this study was conducted on the short-term storage of frozen boar semen in dry ice (-79 °C). Boar semen frozen in LN was transferred to dry ice, kept for 1 day, 3 days, 5 days, 7 days, or 8 days, and then moved back to LN. The quality of frozen semen stored in LN or dry ice was determined to evaluate the feasibility of short-distance transportation with dry ice. The results showed that 60 °C for 8 s was the best condition for thawing frozen semen stored in dry ice. No significant differences in spermatozoa motility, plasma membrane integrity, or acrosome integrity were observed in semen after short-term storage in dry ice compared to LN (p > 0.05). There were no significant changes in antioxidant properties between storage groups either (p > 0.05). In conclusion, dry ice could be used as a cold source for the short-term transportation of frozen boar semen for at least 7 days, without affecting sperm motility, morphological integrity, or antioxidant indices.

Piloting delivery of PfSPZ vaccines for malaria through a cryogenic vaccine cold chain to travel and military medicine clinics

BACKGROUND

PfSPZ vaccines comprising Plasmodium falciparum (Pf) sporozoites (SPZ) have demonstrated > 90% protection against variant Pf malaria infections for at least 12 weeks; they are the only vaccines with the level of efficacy necessary to protect travellers. PfSPZ are eukaryotic cells stabilized by cryopreservation and distributed using a cryogenic (below -150 °C) cold chain. The Ebola vaccine and mRNA vaccines against SARS-CoV-2 pioneered uptake of vaccines requiring non-standard ultra-low temperature cold chains. The cryogenic cold chain using liquid nitrogen (LN2) vapour phase (LNVP) cryoshippers, is simpler, more efficient than -80, -20 or 2-8 °C cold chains, and does not use electricity. This study was conducted to evaluate implementation and integration of a cryogenically distributed vaccine at travel and military immunization clinics.

METHODS

We conducted sequential 28-day studies evaluating vaccine shipping, storage, maintenance and accession at two US military and two civilian travel health/immunization clinics. In each clinic, personnel were trained in equipment use, procurement and handling of LN2, temperature monitoring and inventory record keeping by in-person or video instruction.

RESULTS

Sites required 2-4 h/person for two persons to assimilate and develop the expertise to manage vaccine storage and LNVP operations. LN2 for recharging cryoshippers was delivered every 1-2 weeks. Vaccine ordering, receipt, storage and inventory control was conducted effectively. Simulated single dose vaccine cryovial retrieval and thawing were performed successfully in different travel clinic settings. Continuous temperature monitoring at each site was maintained with only one short excursion above -150 °C (-145 °C) through shipping, use and reverse logistics. Staff, during and at study conclusion, provided feedback that has been incorporated into our models for cold chain logistics.

CONCLUSIONS

These studies demonstrated that the training in delivery, storage, administration and integration of PfSPZ vaccines can be successfully managed in different immunization clinic settings for travellers and military personnel.

Restoring Sperm Quality Post-Cryopreservation Using Mitochondrial-Targeted Compounds

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

Advanced Paternal Age and Future Generations

Paternal age at conception has been increasing. In this review, we first present the results from the major mammalian animal models used to establish that increasing paternal age does affect progeny outcome. These models provide several major advantages including the possibility to assess multi- transgenerational effects of paternal age on progeny in a relatively short time window. We then present the clinical observations relating advanced paternal age to fertility and effects on offspring with respect to perinatal health, cancer risk, genetic diseases, and neurodevelopmental effects. An overview of the potential mechanism operating in altering germ cells in advanced age is presented. This is followed by an analysis of the current state of management of reproductive risks associated with advanced paternal age. The numerous challenges associated with developing effective, practical strategies to mitigate the impact of advanced paternal age are outlined along with an approach on how to move forward with this important clinical quandary.

Sperm Phosphoproteome: Unraveling Male Infertility

Infertility affects approximately 15% of couples worldwide of childbearing age, and in many cases the etiology of male infertility is unknown. The current standard evaluation of semen is insufficient to establish an accurate diagnosis. Proteomics techniques, such as phosphoproteomics, applied in this field are a powerful tool to understand the mechanisms that regulate sperm functions such as motility, which is essential for successful fertilization. Among the post-translational modifications of sperm proteins, this review summarizes, from a proteomic perspective, the updated knowledge of protein phosphorylation, in human spermatozoa, as a relevant molecular mechanism involved in the regulation of sperm physiology. Specifically, the role of sperm protein phosphorylation in motility and, consequently, in sperm quality is highlighted. Additionally, through the analysis of published comparative phosphoproteomic studies, some candidate human sperm phosphoproteins associated with low sperm motility are proposed. Despite the remarkable advances in phosphoproteomics technologies, the relatively low number of studies performed in human spermatozoa suggests that phosphoproteomics has not been applied to its full potential in studying male infertility yet. Therefore, further studies will improve the application of this procedure and overcome the limitations, increasing the understanding of regulatory mechanisms underlying protein phosphorylation in sperm motility and, consequently, in male fertility.

Quantitative phosphoproteomics reveals GSK3A substrate network is involved in the cryodamage of sperm motility

During sperm cryopreservation, the most significant phenotype of cryodamage is the decrease in sperm motility. Several proteomics studies have already been performed to search for key regulators at the protein level. However, sperm functions are known to be highly regulated by phosphorylation signaling. Here, we constructed a quantitative phosphoproteome to investigate the expression change of phosphorylated sites during sperm cryopreservation. A total of 3107 phosphorylated sites are identified and 848 of them are found to be significantly differentially expressed (DE). Bioinformatics analysis showed that the corresponding genes of these regulated sites are highly associated with sperm motility, providing a connection between the molecular basis and the phenotype of cryodamage. We then performed kinase enrichment analysis and successfully identified glycogen synthase kinase-3α (GSK3A) as the key kinase that may play an important role in the regulation of sperm motility. We further constructed a GSK3A centric network that could help us better understand the molecular mechanism of cryodamage in sperm motility. Finally, we also verified that GSK3A was abnormally activated during this process. The presented phosphoproteome and functional associations provide abundant research resources for us to learn the regulation of sperm functions, as well as to optimize the cryoprotectant for sperm cryopreservation.

Role of Antioxidants in Cooled Liquid Storage of Mammal Spermatozoa

Cooled preservation of semen is usually associated with artificial insemination and genetic improvement programs in livestock species. Several studies have reported an increase in reactive oxidative species and a decrease in antioxidant substances and sperm quality parameters during long-term semen storage at refrigerated temperatures. The supplementation of antioxidants in extenders before refrigeration could reduce this detrimental effect. Various antioxidants have been tested, both enzymatic, such as superoxide dismutase and catalase, and non-enzymatic, such as reduced glutathione, vitamins E and C and melatonin. However, the problem of oxidative stress in semen storage has not been fully resolved. The effects of antioxidants for semen-cooled storage have not been reviewed in depth. Therefore, the objective of the present study was to review the efficiency of the supplementation of antioxidants in the extender during cooled storage of semen in livestock species.

Social sperm freezing

Increased paternal age has been associated with lower fertility and higher genetic risk for the offspring. One way to prevent these consequences is to freeze sperm at a young age. Social sperm freezing could be developed in a way similar to social oocyte freezing. The main difference between freezing oocytes and sperm is that social sperm freezing is much less focussed on fertility preservation and much more on avoiding increased genetic risk. Contrary to what some people seem to believe, sperm freezing is more complicated than it looks at first sight. This article considers three practical aspects: freezing, storage and testing. It is concluded that the remedy (cryopreservation) may itself cause damage to the quality of the spermatozoon and to its genetic integrity, thus undoing the possible benefits in terms of fertility and health of offspring.

Membrane lipid replacement with nano-micelles in human sperm cryopreservation improves post-thaw function and acrosome protein integrity

RESEARCH QUESTION

Membrane lipid replacement (MLR) of oxidized membrane lipids can restore sperm cellular membrane functionality and help improve surface protein stability during cryopreservation. What are the effects of MLR with nano-micelles made from a glycerophospholipid (GPL) mixture and cholesterol-loaded cyclodextrin (CLC), on the cryosurvival and expression of acrosome-related proteins in thawed human spermatozoa?

DESIGN

Twenty samples were used to determine the optimum level of nano-micelles by incubation of semen with different concentrations of GPL (0.1 and 1%) and CLC (1 and 2 mg/ml) (including GPL-0.1, GPL-1, CLC-1, CLC-2, CLC-1/GPL-0.1, CLC-2/GPL-0.1, CLC-1/GPL-1 and CLC-2/GPL-1) before cryopreservation. Then, 30 semen samples were collected, and each sample was divided into the following three aliquots: fresh, frozen control and frozen incubated with optimum level of nano-micelles (0.1% GPL and 1 mg/ml CLC).

RESULTS

CLC-1/GPL-0.1 and GPL-0.1 significantly increased motility parameters. CLC-1, GPL-0.1 and CLC-1/GPL-0.1 significantly improved viability rate compared with frozen control group. Significantly higher mitochondrial activity and acrosome integrity, and a lower rate of apoptosis, were observed in the CLC-1/GPL-0.1 compared with the frozen control group. The expression ratios of arylsulfatase A (ARSA), serine protease 37 (PRSS37), serine protease inhibitor Kazal-type 2 (SPINK2) and equatorin (EQTN) significantly increased compared with the frozen control group.

CONCLUSIONS

Modification of membrane cholesterol and GPL mixtures in spermatozoa enhances their acrosome protein integrity by inhibiting early apoptotic changes and spontaneous acrosome reactions.

Acrosome and chromatin integrity, oxidative stress, and expression of apoptosis-related genes in cryopreserved mouse epididymal spermatozoa treated with L-Carnitine

Oxidative stress is believed to be an important cause of sperm damage during freezing. l-Carnitine (LC) may have the potential to improve sperm quality after frozen-thawed process. The present study aimed to investigate the effect of LC supplementation in cryoprotectant media of mouse epididymal sperm on post-thaw sperm quality and expression of apoptosis-related genes. Male BALB/cJ mice spermatozoa were cryopreserved in a cryoprotectant medium containing 2.5 or 5 mM LC. The untreated group was cryopreserved with the cryoprotectant medium only. Six months following cryopreservation, the samples were thawed and sperm quality parameters, chromatin and acrosome integrity, reactive oxygen species (ROS) and glutathione (GSH) levels, mitochondrial activity, and mRNA expression of Bax and Bcl-2 were assessed. The results demonstrated that the concentration of 5 mM LC in cryoprotectant media exhibited higher values for the sperm quality parameters and integrity of chromatin and acrosome in post-thaw spermatozoa than those of the untreated group. Furthermore, sperm ROS levels decreased while GSH and mitochondrial activity levels increased in 5 mM LC group compared to those in the untreated group (P < 0.01). In 5 mM LC-treated group, Bax was down-regulated (P < 0.05) while Bcl-2 was up-regulated (P < 0.001) compared to the untreated group. Collectively, LC supplementation of cryoprotectant medium improved the quality of frozen-thawed mouse epididymal spermatozoa, as showed reduced ROS level and Bax expression as well as increased GSH, mitochondrial activity, and Bcl-2 expression.

Differential motility parameters and identification of proteomic profiles of human sperm cryopreserved with cryostraw and cryovial

Background

Although sperm cryopreservation has been widely used in human reproductive medicine as an integral infertility management in infertility clinics and for banking sperm in sperm banks, the freezing/thawing protocols are not optimal. The freezing and thawing processes result in changes at both structural and molecular levels, some even detrimental, in human sperm when compared with fresh sperm. The change of sperm proteins after cryopreservation may play negative roles for fertilization and early embryo development. Conventionally, cryostraws (CS) and cryovials (CV) are the most widely used cryopreservation carriers (CPCs) for human sperm cryopreservation accompanied with the use of egg yolk free commercial media. However, the influence of cryopreservation on the proteomic profile of human sperm preserved with the two CPCs is unknown. Therefore the purpose of the present study was to compare the frozen-thawed motility, investigate the proteomic profile of human sperm cryopreserved with the two types of CPCs, and identify the susceptible proteins that play key roles for sperm function and fertility.

Methods

The present study compared the cryosurvival of human sperm frozen with the two different CPCs and identified the sperm proteomic changes by using the isobaric tags for relative and absolute quantification labeling technique coupled with 2D LC–MS/MS analysis after freezing and thawing.

Results

Our results indicated that sperm cryopreserved with CV showed higher values for percentage of motile sperm and forward activity rate than those with CS. Compared to fresh sperm, 434 and 432 proteins were differentially identified in human sperm cryopreserved with CS and CV, respectively.

Conclusion

The proteomic profiles of human sperm are greatly affected by cryopreservation with either type of CPC. GO analysis revealed that most of the differentially identified sperm proteins enriched in the extracellular membrane-bounded organelles, cytoplasm and cytosol. In addition, 106 susceptible proteins having known identities related to sperm functions were identified. In general, cryovial seems to be the preferred CPC for human sperm cryopreservation based on the post-thaw motility parameters and the effect on sperm proteomic profiles. These results are beneficial for the insight into the understanding of the cryoinjury mechanism of sperm and the development of human sperm cryopreservation strategies.

Electronic supplementary material

The online version of this article (10.1186/s12014-019-9244-2) contains supplementary material, which is available to authorized users.

Effects of different cryopreservation methods on DNA integrity and sperm chromatin quality in men

BACKGROUND

Cryopreserved human sperm are used in assisted reproductive technology. However, the effect of cryopreservation on sperm DNA integrity is unclear.

OBJECTIVES

The objectives of this study were to: (i) determine the impact of semen cryopreservation on human sperm DNA integrity and chromatin structure; (ii) test if parameters obtained from TUNEL and SCSA® correlate; and (iii) verify correlation between sperm motility, morphology and viability with TUNEL and SCSA® parameters.

MATERIALS AND METHODS

Men attending a fertility clinic were recruited and grouped according to their sperm parameters (n = 9/group): normozoospermia, oligoasthenoteratozoospermia and teratozoospermia. Each semen sample was processed as follow: (i) directly frozen at -80 °C; (ii) diluted in Sperm Maintenance Medium, cooled for 30 min at 4 °C and frozen at -80 °C; (iii) diluted in Sperm Maintenance Medium; or (iv) in SpermFreeze. Each mixture from method (iii) and (iv) was then suspended for 30 min in liquid nitrogen vapor and plunged into liquid nitrogen. After at least two months of storage, samples were thawed at room temperature and analyzed for motility and viability, TUNEL and SCSA® assays.

RESULTS

Progressive motility and viability decreased after freeze-thawing. TUNEL scores increased significantly in all samples after freezing-thawing while no significant change in the DNA fragmentation index (DFI) from SCSA® was observed. No change in the percentage high DNA stainability (HDS) was observed in normozoospermic samples; however it was significantly increased in all the methods in oligoasthenoteratozoospermic and in the methods (ii)-(iv) in teratozoospermic samples. The DFI and TUNEL scores correlated significantly with each other and inversely with sperm motility, viability and morphology.

DISCUSSION AND CONCLUSION

Cryopreservation seems to be deleterious for the integrity of human sperm DNA and compaction. However, the sperm DFI was not affected during cryopreservation under the various methods of storage tested. Clinicians and investigators should take this information into consideration when using cryopreserved sperm for assisted reproduction.

A novel micro-straw for cryopreservation of small number of human spermatozoon

Cryopreservation of few spermatozoa is still a major challenge for male fertility preservation. This study reports use a new micro-straw (LSL straw) for freezing few spermatozoa for intracytoplasmic sperm injection (ICSI). Semen samples from 22 fertile donors were collected, and each semen sample was diluted and mixed with cryoprotectant in a ratio of 1:1, and then frozen using three different straws such as LSL straw (50–100 μl), traditional 0.25 ml and 0.5 ml straws. For freezing, all straws were fumigated with liquid nitrogen, with temperature directly reducing to −130–−140°C. Sperm concentration, progressive motility, morphology, acrosome integrity, and DNA fragmentation index were evaluated before and after freezing. After freezing-thawing, LSL straw group had significantly higher percentage of sperm motility than traditional 0.25 ml and 0.5 ml straw groups (38.5% vs 27.4% and 25.6%, P < 0.003). Sperm motility and acrosomal integrity after freezing-thawing were significantly lower than that of before freezing. However, there was no significant difference in morphology, acrosome, and DNA integrity between the three types of straws (P > 0.05). As LSL straws were thinner and hold very small volume, the freezing rate of LSL straw was obviously faster than 0.25 ml straw and 0.5 ml straws. In conclusion, LSL micro-straws may be useful to store few motile spermatozoa with good recovery of motility for patients undergoing ICSI treatment.

Comparison of effects of thawing entire donor sperm vial vs. partial thawing (shaving) on sperm quality

PURPOSE

Partial thawing of a vial of cryopreserved sperm (shaving) is sometimes applied as a measure to preserve sperm for further use, particularly in cases of very restricted sperm quantity. However, mechanical violence may disrupt the sperm-wall and lead to impaired in-vitro fertilization (IVF) outcomes.

MATERIAL AND METHODS

In a retrospective case-control study at a tertiary, university-affiliated medical center, we compared the IVF/intracytoplasmic sperm injection (ICSI) outcomes of patients who used donor sperm following partial thawing (shaving) of the vial of cryopreserved sperm (n = 99) to a control group consisting of patients for whom the vial of sperm was completely thawed before use (n = 99).

RESULTS

While no differences were observed in the rates of oocyte fertilization, the mean number of top-quality embryos (TQE) was significantly lower in the shaving group than in the complete thawing group (1.33 ± 0.17 vs. 1.87 ± 0.17, p < 0.02). Experimental analysis of aliquots from the same donors revealed significantly reduced motility in sperm samples that were shaved vs. fully thawed (6.5 vs. 37.1%, p < 0.001).

CONCLUSIONS

In cases in which available cryopreserved sperm samples are limited, shaving of the vial without thawing can be used but with caution and only when absolutely necessary. Further, large prospective studies are needed to better clarify whether there is post-thawing sperm damage and to compare IVF outcomes after these two thawing methods.

HBA score in relation to donor semen profiles and live birth rates: a preliminary study

We sought to determine whether sperm donor selection could be improved by using the hyaluronan binding assay (HBA) score to predict live birth rates (LBRs) in donor insemination treatments. Thirty donor samples were included: five fresh samples to assess whether HBA score is affected by cryopreservation and 25 frozen samples from donors whose sperm gave rise to known live births, divided into three groups, with success rates ≥50%, <50-33% and <33%, to examine whether HBA score correlates with LBRs. Correlations with semen analysis parameters, as well as donor demographic factors, known causes of patient subfertility and/or the type of treatment provided were also assessed. There was no significant difference in the mean HBA score pre- and post-cryopreservation (p = 0.998) nor in the HBA score of the three different outcome groups (p = 0.89). HBA score was not significantly affected by other semen analysis parameters (r²=0.394, p = 0.127) or any of the other examined factors. This was the first study to investigate HBA score for cryopreserved donor samples with known LBRs. HBA score was not correlated with LBRs in this small pilot study. Larger studies are required to validate HBA score as a tool for sperm donor selection and predictor of LBRs.

Surgical management of nonobstructive azoospermia

Nonobstructive azoospermia (NOA) is characterized by the complete absence of sperm in the ejaculate due to testicular failure. The evaluation and management of patients with NOA offer a challenge to the reproductive urologist. In the era of in vitro fertilization with intracytoplasmic sperm injection, surgical sperm extraction techniques can afford men with NOA biologic paternity. To provide a comprehensive review of surgical sperm retrieval approaches in the patient with NOA emphasizing complications, success rates and outcome optimization, a Medline search was conducted querying surgical approaches used to manage NOA. Four sperm extraction techniques are described including: testicular sperm aspiration, testicular sperm extraction, fine needle aspiration mapping and microdissection testicular sperm extraction. In addition, the roles for pre-extraction varicocelectomy and sperm cryopreservation are discussed. The management of NOA continues to evolve as newer tools become available. Several modalities of sperm acquisition exist. An understanding of their complications and success rates is fundamental to the treatment of NOA.

Novel Approaches to the Cryopreservation of Human Spermatozoa: History and Development of the Spermatozoa Vitrification Technology

Cryobiology is very intensively applied in reproductive and veterinary medicine for preservation of gametes, embryos and reproductive tissues. Sub-zero temperatures combined with appropriate cryoprotective agents preserve the physiological and reproductive functions of the cells making long-term storage possible without loss of viability. With the use of cryoprotective agents it has become possible to develop cryopreservation techniques, such as the slow conventional freezing and vitrification that are in use in the present times. In slow controlled-rate conventional freezing extracellular ice crystals are formed whereas in vitrification no ice crystals are formed. Glass formation is compatible with the survival of the cell and the preservation of its intracellular structures provided the type(s) and concentrations of cryoprotectant used are not chemo- or osmotoxic. However, irrespective of the type of cooling method employed the cryosurvival of cells and tissues is influenced by the size and maturity of cells, amounts of intracellular water, quality and quantity of intracellular lipids, type of cells, their function and morphology. The intracellular milieu of cryopreserved cells and tissues remain less understood. The application of nanotechnology may help reveal and help advance our knowledge of the cryobiological principles involved in cryosurvival. At this moment the methods of cryopreservation that merit further investigation are vitrification and lyophilization. Vitrification is cheap if reagents are prepared in-house and the procedure can be performed rapidly. It has been successfully applied for gametes and embryos (of different stages of development), and reproductive cells/tissues, somatic cells and stem cells. However, vitrification is more demanding technically and requires operation and storage at sub-zero temperatures. On the other hand lyophilization deserves further investigation because it is a cheaper form of cryopreservation that may enable cryostorage at less demanding temperatures of 4°C and may even allow transport at ambient temperature. These possibilities are explored in this review.

Correlation between male age, WHO sperm parameters, DNA fragmentation, chromatin packaging and outcome in assisted reproduction technology

In the human, male ageing results in reproductive hormonal and cellular changes that can influence semen quality (volume, motility, concentration and morphology) and ultimately result in a reduced fertilising capacity and a longer 'time to pregnancy' for ageing men as well as an increased risk for miscarriage. This prospective cohort study of 278 patients undergoing a first in vitro fertilisation or intracytoplasmic sperm injection treatment was undertaken to examine whether patient's age was reflected in sperm motility, concentration, morphology as well as in DNA fragmentation (DFI) and immature chromatin (unprocessed nuclear proteins and/or poorly condensed chromatin) as measured by the sperm chromatin structure assay. This study also investigated the possible influence of male age (after correcting for female age) on their fertilising capacity, on obtaining a pregnancy and a healthy baby at home. Logistic regression analysis did not reveal any male age-related influences on sperm parameters like concentration, motility or morphology. No significant male age-related increase in DFI or immature chromatin was demonstrable for these patients. Elevated male age, after correcting for female age, was not related to lower fertilisation rates or significant decreases in the chance for a healthy baby at home.

Cumulative pregnancy rate after ICSI with cryopreserved testicular tissue in non-obstructive azoospermia

The aim of the present study was to describe a simplified and inexpensive method of testicular tissue freezing, to assess the cumulative clinical pregnancy rate (CPR) by this technique, and to provide useful information for counselling couples with non-obstructive azoospermia. One hundred and sixty-five couples with non-obstructive azoospermic males pursuing assisted conception, from December 1995 to December 2002, were included. In all cases, the testicular tissue retrieved by open multiple-biopsy (both sides, by testicular sperm extraction) was frozen using a simple liquid nitrogen vapour freezing technique and was stored in liquid nitrogen thereafter. Only mature spermatozoa were used for intracytoplasmic sperm injection (ICSI) after thawing. Expected CPR were calculated using the Kaplan-Meier survival analysis. A total of 281 cycles were performed resulting in 53 clinical pregnancies. Crude and expected CPR (95% confidence intervals) after three cycles were 32.1 (25.7-40.1) and 55.7% (37.0-74.4) respectively. In conclusion, this simplified method for freezing testicular tissue resulted in a satisfactory outcome after ICSI in cases of non-obstructive azoospermia.

Biopreservation of cells and engineered tissues

The development of effective preservation and long-term storage techniques is a critical requirement for the successful clinical and commercial application of emerging cell-based technologies. Biopreservation is the process of preserving the integrity and functionality of cells, tissues and organs held outside the native environment for extended storage times. Biopreservation can be categorized into four different areas on the basis of the techniques used to achieve biological stability and to ensure a viable state following long-term storage. These include in vitro culture, hypothermic storage, cryopreservation and desiccation. In this chapter, an overview of these four techniques is presented with an emphasis on the recent developments that have been made using these technologies for the biopreservation of cells and engineered tissues.

Current and future concepts and practices in human sperm cryobanking

This article focuses on a range of issues that are of current concern to those working in human sperm cryobanking and considers them within a general framework of risk analysis and management, taking into account the available evidence and perceptions of 'best practice' from both the medical and legal perspectives. In particular, issues arising from concerns over the risk of cross-contamination between samples during storage immersed in liquid nitrogen have been analysed in detail. Even though such an occurrence has never been reported for spermatozoa or embryos, and the risk is generally accepted to be vanishingly small, it does represent a finite risk and all reasonable measures should be taken to reduce the chance of its occurring. It is concluded that all methods used to collect, cryopreserve, store, thaw and use cryobanked human spermatozoa must address the risk of contamination from any source throughout the entire process. To assist workers in this area, a series of recommendations as to current best practice are made, based upon conclusions from risk analyses using currently available information.

Retrieval and cryopreservation of sperm from spermatocele fluid

OBJECTIVES

To evaluate the amount, motility, and viability of sperm in fluid aspirated from naturally occurring spermatoceles and to investigate the effect of cryopreservation of sperm retrieved from spermatoceles. Assisted reproductive technologies have led to successful pregnancies and deliveries using sperm harvested from the epididymis and/or testis of infertile men.

METHODS

Aspiration of spermatocele fluid and analysis of the fluid obtained was performed on 20 patients before elective spermatocelectomy. Randomly selected samples (n = 5) were washed using a 70% Percoll gradient, and repeated semen analysis was performed. The washed specimens were cryopreserved in liquid nitrogen, and repeated semen analysis was performed on the thawed specimens.

RESULTS

All spermatoceles (n = 20) had viable sperm present (count range 54 x 10(4) to 326 x 10(6)) and 16 (80%) of 20 contained motile sperm. The average percentage of motile sperm was 5%. The average sperm motility and average percent viability of sperm recovered after Percoll gradient improved compared with sperm in the initial spermatocele aspirates (motility 5%, range 0% to 25% and viability 36%, range 2% to 91% before Percoll vs. motility 13%, range 2% to 38% and viability 39%, range 10% to 92% after Percoll). Sperm retrieved after cryopreservation demonstrated reduced motility and viability; however, motile and viable sperm were recovered from all washed and cryopreserved samples.

CONCLUSIONS

Our results suggest that spermatocele fluid may contain sufficient numbers of sperm for use with assisted reproductive technologies. Motile and viable sperm can be recovered after cryopreservation and storage of sperm obtained from a spermatocele. Spermatocele fluid may be an additional source of sperm for assisted reproductive technologies.