Freezing spermatozoa obtained by testicular fine needle aspiration: a new technique

Tip-microVapour Fast Freezing: A novel easy method for cryopreserving severe oligozoospermic samples

BACKGROUND

Sperm cryopreservation is an important procedure for oligozoospermic subjects at risk of azoospermia and after surgical recovery of spermatozoa in non-obstructive azoospermic men. Conventional procedures for sperm cryopreservation might be, however, not suitable for samples with a very low sperm number.

OBJECTIVES

In this pilot study, we investigated the recoveries of sperm motility and viability in severe oligozoospermic subjects (n = 39) after cryopreservation with a tip-microVapour Fast Freezing, a procedure previously developed by our group for men with good semen quality. Sperm DNA fragmentation was also evaluated in a second group of oligozoospermic samples (n = 16).

MATERIALS AND METHODS

We used a Vapour Fast Freezing procedure using 10 μL tips as carrier, and Test Yolk Buffer as freezing medium (tip-microVapour Fast Freezing). In a subset of samples (n = 22), we compared recovery of motility and viability as obtained with tip-microVapour Fast Freezing and with a Vapour Fast Freezing procedure using 500 μL straws. Sperm DNA fragmentation was evaluated by the sperm chromatin dispersion test.

RESULTS

We found a recovery rate (median [interquartile range]) of 0.29 (0.13-0.41) for progressive motility, 0.30 (0.21-0.52) for total motility and 0.48 (0.29-0.60) for viability. Interestingly, we observed that samples with the poorest motility were apparently less damaged by freezing/thawing. In a subset of samples (n = 22), we directly compared values of viability, progressive motility and total motility by freezing/thawing with tip-microVapour Fast Freezing and Vapour Fast Freezing conducted with 500 μL straws. We found much better values of all sperm parameters in samples after freezing/thawing with tip-microVapour Fast Freezing than with Vapour Fast Freezing in 500 μL straws: that is, progressive motility: 7.00 (3.00-8.50)% versus 2.00 (0.00-4.25)%, p < 0.001; total motility: 12.00 (8.00-16.25)% versus 6.50 (1.00-9.25)%, p < 0.001; viability: 29.75 (23.75-45.25) versus 22.50 (13.75-28.13), p < 0.001, respectively. In the second group of oligozoospermic samples, we found that tip-microVapour Fast Freezing produced lower levels of sperm DNA fragmentation than straws (33.00 [19.75-36.00]% vs. 36.00 [22.75-41.87]%, p < 0.001).

DISCUSSION AND CONCLUSION

Tip-microVapour Fast Freezing appears to be a very promising method to cryopreserve semen samples from severe oligozoospermic patients.

Vapour fast freezing with low semen volumes can highly improve motility and viability or DNA quality of cryopreserved human spermatozoa

Objectives

To challenge a vapour fast freezing (VFF) cryopreservation procedure (conventional VFF) with several vitrification protocols and VFF conducted with small semen volumes (10 μl, microVFF), in order to implement a procedure for sperm banking in subjects with small sperm number.

Materials and methods

Conventional VFF was conducted with test yolk buffer (TYB) as freezing medium and 500 μl straws as carriers. MicroVFF was conducted with TYB and using tips or cell sleepers as carriers. Vitrification was performed with TYB or SpermFreeze as freezing medium and with microspheres and tips as carriers. The effect of different procedures on progressive and total motility, viability, oxidative stress and DNA fragmentation of spermatozoa (sDF) was determined. Fresh and thawed samples, the latter after adequate washing/centrifuging, were evaluated. In some experiments, motility and viability recovery was determined in thawed samples, omitting the washing/centrifuging step.

Results

All the cryopreservation procedures blunted sperm motility and viability and induced increase of oxidative stress and sDF. However, VFF better preserved sperm motility and viability and less induced oxidative stress and sDF than vitrification, independently from the freezing medium and the carriers used in the latter. MicroVFF with cell sleepers resulted in a percentage increase of 57.58 ± 63.63%, 48.82 ± 74.96% and 24.55 ± 39.20% of, respectively, progressive and total motility and viability compared to the conventional VFF. Further, when tips were used, microVFF resulted in a percentage decrease of 15.77 ± 20.77% of sDF with respect to conventional VFF. Finally, omission of washing/centrifuging in post thawed samples, resulted in a much lower negative effect on motility and viability.

Discussion and conclusion

VFF, and in particular microVFF, better prevents sperm cryodamage than vitrification. Washing/centrifuging step after sample thawing seems to be responsible for a relevant fraction of damage to sperm motility and viability. Overall, our results are promising for developing a novel strategy of sperm banking in subjects with small sperm number, where low semen volumes are mandatory.

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

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

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

Cryopreservation of single-sperm: where are we today?

BACKGROUND

Patients with severe oligospermia and nonobstructive azoospermia have very limited numbers of viable sperm in their epididymal and testicular samples. Thus, cryopreservation of their sperm is performed to avoid repeated sperm retrievals and to preserve their sperm from any side effects of any treatment regimens.

MAIN BODY

The development of intracytoplasmic sperm injection technology has extended the therapeutic capacity of assisted reproductive technology for men with azoospermia via the surgical or percutaneous isolation of sperm from the testis/epididymis. The conventional cryopreservation techniques are inadequate for preserving individually selected sperm. The technique for freezing single sperm was first developed in 1997 and has been explored from the perspective of frozen carriers, freezing programs, and cryoprotectant formulations. Among these methods, advances in frozen carriers have directly improved single-sperm freezing technology. In this review, we evaluate the different technologies for the cryopreservation of single sperm by discussing the advantages and disadvantages of different freezing methods, their clinical applications, and the outcomes for a range of frozen carriers.

CONCLUSION

Our review article describes the latest and current technologies implemented for the cryopreservation of single sperm that could potentially benefit patients with severe oligospermia and who rarely have any sperm in their ejaculate. This review provides a platform to understand the process and pitfalls of single-sperm cryopreservation to ensure further improvements in the cryopreservation technology in future studies.

Evaluation and improvement of the novel method for vitrification of a few human sperms

RESEARCH QUESTION

The purposes of this study are to evaluate the performance of the novel SpermVD device on vitrification of a few human sperms, and determine whether PICSI dish and density gradient centrifugation can improve the quality of sperm after thawing.

DESIGN AND METHODS

In order to determine the suitable preparation methods, both washed sperm and neat sperm were selected in ICSI dish and PICSI dish, and frozen with the novel SpermVD device. The selected sperms were transferred to freezing droplets with 1 μl droplet of a 50/50 v/v mixture of QA Sperm Freezing Medium and QA Medium w/Hepes on the SpermVD wells. And the device was exposed to vapor of liquid nitrogen for 5 min and then placed into LN₂ immediately. The sperms were thawed in a 37℃ oil filled dish which contained QA Medium w/Hepes droplets and they were searched and revaluated immediately. The frozen effects of sperm were evaluated by progressive motility, motility, viability and recovery rates of freezing-thawing sperm.

RESULTS

After freezing-thawing, the overall sperm recovery rate was 94.2% with 70% viability, 20.7% progressive motility, and 36.2% motility. The progressive motility, motility, viability and recovery rates of washed sperm were lower than that of the neat sperm, with a significant difference (P <  0.01) at both viability and motility rates. In addition, the viability rate was significantly higher in PICSI dish group than that of ICSI dish group (P <  0.01) and the motility, recovery and progressive motility rates were not significantly different between the two groups (P > 0.05).

CONCLUSIONS

The spermVD device was one of the effective platforms for freezing a few human sperms and using PICSI dish to select mature neat sperms could improve the quality of sperm after thawing. Density gradient centrifugation might be not required or suitable sperm preparation methods before freezing.

Testicular Fine-Needle Aspiration for Sperm Retrieval in Azoospermia: A Small Step toward the Technical Standardization

PURPOSE

The aim was to describe our preliminary experience performing testicular fine-needle aspiration (TEFNA) with a larger needle in infertile patients with obstructive azoospermia, and to provide a systematic literature review of the different testicular sperm aspiration techniques, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement recommendations.

MATERIALS AND METHODS

We prospectively collected data between March 2017 and June 2018. All men underwent bilateral TEFNA under analgo-sedation, using a larger disposable 18-gauge butterfly needle with 60 mL Luer-Lock syringe attached to it.

RESULTS

Thirty consecutive patients were enrolled. Median operative time was 16 minutes (interquartile range [IQR]: 12-30 minutes). No intraoperative complications occurred. Two/thirty patients (6.7%) reported postoperative adverse events: 1 patient had prolonged orchialgia, 1 patient presented scrotal hematoma. Successful sperm retrieval was found in 28/30 cases (93.3%). Median sperm concentration was 0.05 ×10⁶/mL (IQR: 0.001-0.1 ×10⁶/mL). Median total sperm motility was 10% (IQR: 0%-15%). In 20/30 men (66.7%) sperm retrieved was used for fresh intracytoplasmic sperm injection cycle, in 8/30 (26.7%) sperm cryopreservation was necessary, because on the day of sperm retrieval the female resulted not responder to ovarian stimulation. In this cases mean number of 3 (IQR: 1-4) bio system straws was cryopreserved.

CONCLUSIONS

TEFNA with 18-gauge needle proved to be a feasible, safe and effective treatment, even if future prospective studies will be addressed to clarify what type of azoospermia benefits from this procedure, and if a larger needle permits to improve Assisted Reproductive Technologies (ART) outcomes.

An adapted carrier for the cryopreservation of human testicular spermatozoa

RESEARCH QUESTION

Does the adapted carrier Cryoplus improve the quality of cryopreserved spermatozoa compared with the use of conventional containers, and what is the effect of the adapted carrier on clinical outcomes?

DESIGN

Semen samples from 27 cases of oligozoospermia were used to investigate whether the adapted carrier improved cryopreserved sperm quality compared with the use of 0.25-ml straws and 2-ml cryogenic vials. Thirty testicular sperm samples were used to study the quality of testicular spermatozoa cryopreserved in the adapted carrier. The retrospective study included a further 104 men with azoospermia to investigate the clinical outcomes of testicular spermatozoa cryopreserved with the adapted carriers. Men with mostly obstructive azoospermia were included in this study.

RESULTS

The adapted carrier improved cryopreserved spermatozoa motility of semen samples compared with 2-ml cryogenic vials but not compared with 0.25-ml straws. No differences were found in cryopreserved sperm DNA fragmentation among the three carriers. Fertilization and good-quality embryo rates were similar in ICSI cycles using fresh or cryopreserved testicular spermatozoa. Additionally, no difference was evident between frozen-thawed embryo transfer cycles using fresh or cryopreserved testicular spermatozoa in clinical pregnancy, implantation, miscarriage, live birth rates or birth weight.

CONCLUSIONS

The adapted carrier improved the cryopreserved sperm motility compared with the effects of 2-ml cryogenic vials. The outcomes of intracytoplasmic sperm injection and frozen-thawed embryo transfer outcomes indicate that testicular spermatozoa cryopreserved using the adapted carrier is not inferior to fresh testicular spermatozoa. The use of the adapted carrier for cryopreserving human testicular spermatozoa especially from obstructive azoospermia is simple and effective.

Successful delivery derived from cryopreserved rare human spermatozoa with novel cryopiece

Herein, we report the clinical outcomes following intracytoplasmic sperm injection (ICSI) with cryopiece cryopreserved rare human spermatozoa from severe male factor infertility patients. We established a novel cryopiece system on the basis of previous studies. In this study, 126 spermatozoa from four patients with non-obstructiveazoospermia (NOA) or severe oligozoospermia were stored in cryopiece and then thawed on the day of the oocyte retrieval, 88 (83%) spermatozoa were recovered with a 47.5% (38 of 80) motile rate. Routine ICSI were performed in enrolled 30 MII oocytes from their spouse with their own spermatozoa, respectively. Twenty-two (73%) fertilization and 19 (86%) zygote cleavage were observed. Finally, a total of 11 embryos were achieved and each female patient received a transplantation of two fresh embryos. Four healthy babies were born at term. In conclusion, our novel cryopiece can be applied in assisted reproduction through ICSI with an effective motile spermatozoa recovery rate, high fertilization rate, and successful pregnancy result.

Intracytoplasmic sperm injection outcomes with cryopreserved testicular sperm aspiration samples

Intracytoplasmic sperm injection (ICSI) may be performed with testicular frozen-thawed spermatozoa in patients with nonobstructive azoospermia (NOA). Sperm retrieval can be performed in advance of oocyte aspiration, as it may avoid the possibility of no recovery of spermatozoa on the day of oocyte pickup. There are few studies available in the literature concerning the use of frozen-thawed spermatozoa obtained from testicular sperm aspiration (TESA). To evaluate the effects and the outcomes of ICSI with frozen-thawed spermatozoa obtained by TESA, we performed a retrospective analysis of 43 ICSI cycles using frozen-thawed TESA. We obtained acceptable results with a fertilisation rate of 67.9%, an implantation rate (IR) of 17.1%, and clinical and ongoing pregnancy rates of 41.9% and 37.2% respectively. The results of this study suggest that performing ICSI using cryopreserved frozen-thawed testicular spermatozoa with TESA as a first option is a viable, safe, economic and effective method for patients with NOA.

Cryopreservation of testicular and epididymal sperm: techniques and clinical outcomes of assisted conception

The introduction of the technique of intracytoplasmic sperm injection to achieve fertilization, especially using surgically retrieved testicular or epididymal sperm from men with obstructive or non-obstructive azoospermia, has revolutionized the field of assisted reproduction. The techniques for the retrieval of spermatozoa vary from relatively simple percutaneous sperm aspiration to open excision (testicular biopsy) and the more invasive Micro-TESE. The probability of retrieving spermatozoa can be as high as 100% in men with obstructive azoospermia (congenital bilateral absence of the vas deferens, status post-vasectomy). However, in nonobstructive azoospermia, successful sperm retrieval has been reported in 10-100% of cases by various investigators. The surgical retrieval and cryopreservation of sperm, especially in men with non-obstructive azoospermia, to some extent ensures the availability of sperm at the time of intracytoplasmic sperm injection. In addition, this strategy can avoid unnecessary ovarian stimulation in those patients intending to undergo in vitro fertilization-intracytoplasmic sperm injection with freshly retrieved testicular sperm when an absolute absence of sperm in the testis is identified. Several different methods for the cryopreservation of testicular and epididymal sperm are available. The choice of the container or carrier may be an important consideration and should take into account the number or concentration of the sperm in the final preparation. When the number of sperm in a testicular biopsy sample is extremely low (e.g., 1-20 total sperm available), the use of an evacuated zona pellucida to store the cryopreserved sperm has been shown to be an effective approach.

Successful delivery derived from vitrified-warmed spermatozoa from a patient with nonobstructive azoospermia

OBJECTIVE

To report the clinical outcomes following intracytoplasmic sperm injection (ICSI) with vitrified sperm from patients with severe male factor infertility.

DESIGN

Retrospective case series.

SETTING

IVF unit of a medical center.

PATIENT(S)

Three patients with severe oligozoospermia or nonobstructive azoospermia (NOA).

INTERVENTION(S)

Cryopreservation of limited numbers of spermatozoa with the use of Cryotop and Cell Sleeper as nonbiologic containers.

MAIN OUTCOME MEASURE(S)

Four cycles underwent intracytoplasmic sperm injection (ICSI) with vitrified sperm.

RESULT(S)

A total of 148 spermatozoa in 18 containers (8.2 sperm per container) were vitrified and 36 of them (5 containers) were warmed. Thirty-three sperm (92%) were retrieved successfully and injected individually into 17 mature oocytes. Fertilization was observed in 12 oocytes (71%), and all zygotes (100%) cleaved. A couple with NOA achieved a singleton pregnancy and concluded with full-term delivery of a healthy boy (2,632 g).

CONCLUSION(S)

A successful delivery was achieved after transfer of a blastocyst derived from vitrified-warmed spermatozoa. A small number of vitrified sperm cells were used for ICSI to fertilize oocytes with predictable timing.

Human Sperm Cryopreservation: Update on Techniques, Effect on DNA Integrity, and Implications for ART

Cryopreservation of human spermatozoa-introduced in the 1960's-has been recognized as an efficient procedure for management of male fertility before therapy for malignant diseases, vasectomy or surgical infertility treatments, to store donor and partner spermatozoa before assisted reproduction treatments and to ensure the recovery of a small number of spermatozoa in severe male factor infertility. Despite the usefulness of it, cryopreservation may lead to deleterious changes of sperm structure and function: while the effects of cryopreservation on cells are well documented, to date there is no agreement in the literature on whether or not cryopreservation affects sperm chromatin integrity or on the use of a unique and functional protocol for the freezing-thawing procedure. Therefore, sperm cryopreservation is an important component of fertility management and much of its successful application seems to affect the reproductive outcome of assisted reproduction technologies (ART): appropriate use of cryoprotectants before and sperm selection technologies after cryopreservation seem to have the greatest impact on preventing DNA fragmentation, thus improving sperm cryosurvival rates.

Simple vitrification for small numbers of human spermatozoa

Conventional freezing procedures and containers are not appropriate for spermatozoa from the testis because of their low number and poor in-situ motility, and various types of container have been utilized to freeze small numbers of spermatozoa. This study tried to develop a vitrification method for small numbers of spermatozoa using the Cell Sleeper, which is a closed type of cell-cryopreservation container. The container with spermatozoa were cooled in liquid nitrogen vapour and then stored in a cryotank. Sperm motility parameters improved significantly (P < 0.05) by vitrification in oil-free droplets rather than in droplets covered with oil. After vitrification of five spermatozoa per container, all spermatozoa were recovered and the viable sperm rate was significantly higher when spermatozoa were vitrified in a 3.5-ll droplet rather than in 0.5 ll (72.0% versus 38.0%; P < 0.01). Recovery, motility and viability rates of vitrified–warmed spermatozoa were similar between the Cell Sleeper and the CryoTop groups. In conclusion, the Cell Sleeper is a highly effective tool for the cryopreservation of small numbers of spermatozoa and limited cells can be vitrified quickly and simply without significant loss.

A novel method for cryopreservation of individual human spermatozoa

The purpose of this study is to develop a novel method for the cryopreservation and efficient post-thaw recovery of individual or small numbers of human spermatozoa. Spermatozoa equilibrated in cryoprotectant buffer were injected with an intracytoplasmic sperm injection (ICSI) needle into a droplet of cryoprotectant on a homemade cryoleaf. The droplet was of cryoprotectant and seminal plasma at a ratio of 1:1. The sperm-loaded cryoleaf was slowly lowered over and stored in liquid nitrogen. Spermatozoa were thawed in a 37°C oil bath without dilution and centrifugation. To test the fertilizing ability of these spermatozoa, the recovered spermatozoa were injected by ICSI into 1-d-old or in vitro-matured human oocytes. Fresh spermatozoa from the same semen samples served as controls. The trials were performed in two separate experiments. In the first set of experiments, 92 spermatozoa were thawed and carefully investigated. The spermatozoa from percutaneous epididymal sperm aspiration had a motility recovery of 92.9% (13/14); ejaculated spermatozoa had a motility recovery of 61.5% (48/78), and only 1.3% (1/78) was lost. Together in the first and second set of experiments, the fertilization rates for the fresh and frozen-thawed spermatozoa were 67.6% (25/37) and 60.6% (40/66), respectively (P = 0.052). The mean embryo cleavage rates in the fresh and frozen-thawed groups were 88% (22/25) and 85% (34/40), respectively (P = 0.990). This cryopreservation method for individual or small numbers of human spermatozoa was efficient and simple. These findings make this method a promising technique for the clinical application of ejaculated sperm from oligozoospermic patients.

Techniques for cryopreservation of individual or small numbers of human spermatozoa: a systematic review

BACKGROUND

Despite interest in cryopreservation of individual or small number of human spermatozoa, to date, little data is available as regards its effectiveness. We systematically reviewed the outcome after cryopreservation of individual or small numbers of human spermatozoa in patients with severe male factor of infertility.

METHODS

We searched the MEDLINE, EMBASE, Cochrane Systematic Reviews, CENTRAL, Web of Science, Scopus databases for relevant studies up to June of 2008. The search used terms referring to cryopreservation of small amount of sperm. Included studies were limited to human studies with no language restrictions.

RESULTS

We identified 30 reports including 9 carriers used for cryopreservation of small quantities/numbers of human spermatozoa (7 non-biological and 2 biological carriers). A wide variety of cryopreservation vehicles were reported. The recovery rate of spermatozoa cryopreserved in a known small number varied widely from 59 to 100%. Fertilization rates were in the range of 18-67%. Frozen-thawed spermatozoa, using this method, were subsequently used for intracytoplasmic sperm injection in only five studies, with few pregnancies reported so far. To date, there remains no consensus as to the ideal carrier for cryopreservation of small number of spermatozoa for clinical purposes.

CONCLUSIONS

Cryopreservation of individual or small numbers of human spermatozoa may replace the need for repeated surgical sperm retrieval. A controlled multicenter trial with sufficient follow-up would provide valid evidence of the potential benefit of this approach.