Optimizing human semen cryopreservation by reducing test vial volume and repetitive test vial sampling

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.

The impact of cryopreservation on the morphology of spermatozoa in men with oligoasthenoteratozoospermia

The cryopreservation of ejaculate can reduce the viability, motility, and morphological characteristics of the spermatozoa of infertile men. Oligoasthenoteratozoospermia (OAT) is the most common cause of male subfertility. The aim of this study was to evaluate the morphological characteristics and viability of progressive motile sperm fraction before and after cryopreservation, and to determine whether cryopreservation of progressive motile sperm fraction is effective in eliminating morphologically abnormal sperm in men with OAT. An increased proportion of spermatozoa with normal morphology in fresh progressive motile sperm fraction compared with fresh ejaculate has been observed. After cryopreservation, the motility was 65.5 ± 8.8%; the proportion of spermatozoa with normal morphology increased non-significantly compared with freshly prepared motile sperm fraction (35.6 ± 5.5%). Concurrently, the proportion of cryopreserved spermatozoa with head defects increased significantly by 1.7 times (to 38.4 ± 4.7%) and the proportion of almost all morphologically abnormal sperm cells, particularly spermatozoa with multiple abnormalities, was reduced significantly. These data appear to be a novel finding in the context of patients with OAT. Using such spermatozoa for in vitro fertilization leads to a significant decrease in both a number of embryos at the cleavage stage and the blastocysts formation rate. High-magnification sperm morphology examination and selection, IMSI, post-cryopreservation significantly increased the likelihood of successful oocyte fertilization and subsequent embryo development.

Fertility preservation options for transgender individuals

Gender affirming medical and surgical treatments affect the reproductive potential of transgender individuals. Prior to the development of assisted reproductive technologies (ART), genital gender-affirming surgery frequently eliminated a patient’s reproductive potential. Today, all patients should be counseled on their fertility preservation (FP) options before medical and surgical transition, yet this appears to seldom occur in practice. The following review is the result of a systematic literature search of PubMed, Medline and Google Scholar to identify current and future FP options, barriers to treatment patients face, practice patterns of transgender health care providers, and if there were any standardized counseling protocols. Options for transwomen at any point in their transition range from simply providing a semen sample to be used with assistive reproductive techniques to experimental techniques involving testicular cryopreservation followed by in vitro initiation of spermatogenesis. Transmen before and after starting hormone therapy can pursue any assistive reproductive techniques available for ciswomen. Future options currently under investigation include ovarian tissue cryopreservation (OTC) with in vitro oocyte maturation. In addition to counseling about their FP options, patients should be advised prospectively about the requirements, process details, the total costs associated with achieving pregnancy, and the inherent risks associated with using preserved genetic material including risk of failure, and maternal and fetal health risks. Transgender patients report using assistive reproductive services difficult, due to a lack of dialogue about fertility and the lack of information offered to them- presumably because their circumstances do not fit into a traditional narrative familiar to providers. Physicians and health care providers would benefit from better educational tools to help transgender patients make informed decisions and better training about transgender patients in general, and FP options available to them.

Post-thaw recovery of rare or very low concentrations of cryopreserved human sperm

OBJECTIVE

To analyze cases in which no sperm could be identified after thawing among cryopreserved samples of rare or very low concentrations of sperm.

DESIGN

Retrospective, single-institution, cross-sectional.

SETTING

Male infertility clinic.

PATIENT(S)

We identified couples that underwent intracytoplasmic sperm injection (ICSI) with the use of either ejaculated or testicular cryopreserved-thawed sperm. Inclusion criteria were men with <100,000 total ejaculated sperm or men with azoospermia due to spermatogenic dysfunction who underwent microsurgical testicular sperm extraction with similarly low pre-cryopreservation sperm counts. Pre-cryopreservation specimens were categorized as "rare sperm only" (Group 1) or <100,000 total sperm (group 2). "Rare sperm only" applied to cases in which only one to three sperm were identified in a search of >20 high-power fields.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Cases in which no sperm were able to be found post-thaw (i.e., complete cellular loss) for use at the time of a programmed IVF cycle.

RESULT(S)

We analyzed 55 men (83 ICSI cycles). There were five ICSI cycles (6.0%) among five different couples in which no sperm could be identified post-thaw. Of these, four cases were from group 1 (8.5%) and one from group 2 (2.8%). Complete cellular loss occurred in 5.8% of testicular sperm samples and 7.1% of ejaculated sperm samples. There were no statistical associations between the ability to locate sperm post-thaw and the pre-cryopreservation parameters or sperm source.

CONCLUSION(S)

Failure to retrieve any sperm after thawing of rare or very low concentrations of cryopreserved sperm is an infrequent event and largely limited to those patients with rare quantities of sperm.

Open encapsulation-vitrification for cryopreservation of algae

Vitrification offers a cost-effective solution for the preservation and management of genetic resources with, low-cost international movement of selected genetic materials and for long-term maintenance of stable stocks of a wide variety of microorganisms. However, its success is limited by the wide range of algal species. Here, we report a simple open encapsulation-vitrification protocol of cryopreservation. Results showed that ∼58% and ∼27% of Oocystis sp. survived vitrification-warming after the open and closed system of vitrification respectively when compared to non-cryopreserved controls. The improved success in an open system of vitrification was also observed in Anabaena sp. Furthermore, with the addition of 2-mercaptoethanol or glutathione the post-warming viability of vitrified algae in both open and closed system of vitrification was significantly improved (p < 0.05). The present case study aimed to develop a vitrification-based cryopreservation protocol and confirms an improvement in survival percentage over conventional encapsulation-vitrification method.