In vitro spermatogenesis: Why meiotic checkpoints matter

Successful in vitro spermatogenesis would generate functional haploid spermatids, and thus, form the basis for novel approaches to treat patients with impaired spermatogenesis or develop alternative strategies for male fertility preservation. Several culture strategies, including cell cultures using various stem cells and ex vivo cultures of testicular tissue, have been investigated to recapitulate spermatogenesis in vitro. Although some studies have described complete meiosis and subsequent generation of functional spermatids, key meiotic events, such as chromosome synapsis and homologous recombination required for successful meiosis and faithful in vitro-derived gametes, are often not reported. To guarantee the generation of in vitro-formed spermatids without persistent DNA double-strand breaks (DSBs) and chromosomal aberrations, criteria to evaluate whether all meiotic events are completely executed in vitro need to be established. In vivo, these meiotic events are strictly monitored by meiotic checkpoints that eliminate aberrant spermatocytes. To establish criteria to evaluate in vitro meiosis, we review the meiotic events and checkpoints that have been investigated by previous in vitro spermatogenesis studies. We found that, although major meiotic events such as initiation of DSBs and recombination, complete chromosome synapsis, and XY-body formation can be achieved in vitro, crossover formation, chiasmata frequency, and checkpoint mechanisms have been mostly ignored. In addition, complete spermiogenesis, during which round spermatids differentiate into elongated spermatids, has not been achieved in vitro by various cell culture strategies. Finally, we discuss the implications of meiotic checkpoints for in vitro spermatogenesis protocols and future clinical use.

Cryopreservation of Sperm: Effects on Chromatin and Strategies to Prevent Them

Cryopreservation is a technique that can keep sperm alive indefinitely, enabling the conservation of male fertility. It involves the cooling of semen samples and their storage at -196 °C in liquid nitrogen. At this temperature all metabolic processes are arrested. Sperm cryopreservation is of fundamental importance for patients undergoing medical or surgical treatments that could induce sterility, such as cancer patients about to undergo genotoxic chemotherapy or radiotherapy, as it offers these patients not only the hope of future fertility but also psychological support in dealing with the various stages of the treatment protocols.Despite its importance for assisted reproduction technology (ART) and its success in terms of babies born, this procedure can cause cell damage and impaired sperm function. Various studies have evaluated the impact of cryopreservation on chromatin structure, albeit with contradictory results. Some, but not all, authors found significant sperm DNA damage after cryopreservation. However, studies attempting to explain the mechanisms involved in the aetiology of cryopreservation-induced DNA damage are still limited. Some reported an increase in sperm with activated caspases after cryopreservation, while others found an increase in the percentage of oxidative DNA damage. There is still little and contradictory information on the mechanism of the generation of DNA fragmentation after cryopreservation. A number of defensive strategies against cryoinjuries have been proposed in the last decade. Most studies focused on supplementing cryoprotectant medium with various antioxidant molecules, all aimed at minimising oxidative damage and thus improving sperm recovery. Despite the promising results, identification of the ideal antioxidant treatment method is still hampered by the heterogeneity of the studies, which describe the use of different antioxidant regimens at different concentrations or in different combinations. For this reason, additional studies are needed to further investigate the use of antioxidants, individually and in combination, in the cryopreservation of human sperm, to determine the most beneficial conditions for optimal sperm recovery and preservation of fertility.

Non-oncologic Indications for Male Fertility Preservation

PURPOSE OF REVIEW

To explore non-oncologic indications for male fertility preservation.

RECENT FINDINGS

Common scenarios in which male fertility could be irreversibly compromised include autoimmune conditions requiring treatment with cyclophosphamide, gender dysphoria prior to starting hormone therapy, military deployment, and critical illness. Fertility preservation should be considered with particular attention to the timing and logistics specific to each scenario. Recognition and familiarity with such situations will help physicians provide better counseling to patients and their families, improve the quality of decision-making, and ultimately reduce missed opportunities and regret.

To What Extent Are Cryopreserved Sperm and Testicular Biopsy Samples Used in Assisted Reproduction?

BACKGROUND

Testicular biopsies and ejaculated spermatozoa are routinely cryopreserved in many units but the fate of these samples has not provoked large interest. This prompted us to review our data accumulated during a period of 20 years (1997 to 2016).

METHODS

For patients with biopsies (group 1) or ejaculated spermatozoa (group 2), an attempt was made to evaluate whether the samples stored, had been discarded with the patient's consent or because the patient had died, or whether they had been transported to another laboratory. In each of these categories, a previous use in our program of assisted reproduction was assessed.

RESULTS

The total utilization rate in group 1 (n=95) was 53.7% and only 5.48% in group 2 (n=365). In both groups, deceased patients had not previously used their cryopreserved samples. In detail, the utilization rates for still banked, discarded and transferred samples were 84.2%, 50% and 27.3%, respectively in group 1 and 2.88%, 10.4% and 10%, respectively in group 2.

CONCLUSION

The exact reasons for the low utilization rates of cryopreserved male gametes remain to be explored. A closer contact between sperm banking units and patients might be useful to discuss the need for further storage of the probes, their possible disposal or the prospects when a specific use for assisted reproduction is intended.

The protective effect of regucalcin against radiation-induced damage in testicular cells

AIMS

Regucalcin (RGN), a protein broadly expressed in the male reproductive tract, has shown to have beneficial effects on spermatogenesis suppressing chemical-induced apoptosis. This study aimed to evaluate whether RGN overexpression ameliorates the spermatogenic phenotype after radiation treatment.

MAIN METHODS

Transgenic rats overexpressing RGN (Tg-RGN) and their wild-type (Wt) counterparts were exposed to a single dose of X-rays (6Gy), and at ten weeks after irradiation, the testicular status and the epididymal sperm parameters were evaluated. The expression of RGN and several cell cycle and apoptosis regulators, the enzymatic activity of caspase-3, and RGN immunostaining were also assessed.

KEY FINDINGS

Tg-RGN animals displayed higher gonadosomatic index, and augmented sperm viability and motility relatively to their Wt counterparts after irradiation, as well as higher frequency of normal sperm morphology and a diminished incidence of head-defects. The differences in reproductive parameters were underpinned by a lower rate of apoptosis, as evidenced by the reduced activity of caspase-3, lower levels of caspase-8, and increased Bcl-2/Bax ratio in the testis of Tg-RGN animals. Supporting the involvement of RGN in the anti-apoptotic response, an enhanced expression of RGN was observed in irradiated rats.

SIGNIFICANCE

Transgenic-overexpression of RGN protected against radiation-induced testicular damage, which strengthens the role of this protein protecting cells from the damage of external agents. These findings also indicated that the modulation of RGN testicular levels would be a mechanism for fertility preservation in men undergoing oncological treatment.

Quebec public funding facilitates fertility preservation for male cancer patients

BACKGROUND

Sperm cryopreservation remains the only clinically feasible option to preserve male fertility. The quality of counselling provided by the treating physicians and the cost of sperm cryopreservation can both influence a patient's decision about whether to preserve sperm. On 5 August 2010, the Quebec government introduced provincial coverage of assisted reproductive technologies, with sperm cryopreservation included as a covered service. The aim of the present study was to evaluate whether and how such a program affects the behaviour of cancer patients with respect to sperm cryopreservation.

METHODS

We analyzed the database derived from male patients undergoing sperm cryopreservation from August 2008 to August 2012 at our centre. The retrieved data included patient age, male infertility or oncologic diagnosis, sperm quality parameters, and details about the number of visits for sperm cryopreservation.

RESULTS

The number of cancer patients who cryopreserved sperm before and after the policy change did not differ significantly, but a marked increase in the number of non-cancer patients was observed. Further analysis revealed that, after implementation of the public funding program, the total number of sperm cryopreservation sessions per patient increased significantly in cancer patients but not in non-cancer patients.

CONCLUSIONS

It appears that cancer patients who are willing to freeze sperm are keen to return for more sessions of sperm banking when no fees are associated with the service. Those findings suggest that cost reduction is an important factor for improving delivery of fertility preservation services to male cancer patients.