Development of Postmeiotic Cells In Vitro from Spermatogonial Cells of Prepubertal Cancer Patients

Effect of IL-1β on the Development of Spermatogenesis In Vitro in Normal and Busulfan-Treated Immature Mice

Gonadotoxic agents could impair spermatogenesis and may lead to male infertility. The present study aimed to evaluate the effect of IL-1β on the development of spermatogenesis from cells isolated from seminiferous tubules (STs) of normal and busulfan-treated immature mice in vitro. Cells were cultured in a 3D in vitro culture system for 5 weeks. We examined the development of cells from the different stages of spermatogenesis by immunofluorescence staining or qPCR analyses. Factors of Sertoli and Leydig cells were examined by qPCR analysis. We showed that busulfan (BU) treatment significantly reduced the expression of testicular IL-1β in the treated mice compared to the control group (CT). Cultures of cells from normal and busulfan-treated immature mice induced the development of pre-meiotic (Vasa), meiotic (Boule), and post-meiotic (acrosin) cells. However, the percentage of developed Boule and acrosin cells was significantly lower in cultures of busulfan-treated mice compared to normal mice. Adding IL-1β to both cultures significantly increased the percentages of Vasa, Boule, and acrosin cells compared to their controls. However, the percentage of Boule and acrosin cells was significantly lower from cultures of busulfan-treated mice that were treated with IL-1β compared to cultures treated with IL-1β from normal mice. Furthermore, addition of IL-1β to cultures from normal mice significantly increased only the expression of androgen receptor and transferrin but no other factors of Sertoli cells compared to their CT. However, the addition of IL-1β to cultures from busulfan-treated mice significantly increased only the expression of androgen-binding protein and the FSH receptor compared to their CT. Adding IL-1β to cultures of normal mice did not affect the expression of 3βHSD compared to the CT, but it significantly reduced its expression in cultures from busulfan-treated mice compared to the CT. Our findings demonstrate the development of different stages of spermatogenesis in vitro from busulfan-treated mice and that IL-1β could potentiate this development in vitro.

Effect of Temperature on the Development of Stages of Spermatogenesis and the Functionality of Sertoli Cells In Vitro

Spermatogenesis is the process of proliferation and differentiation of spermatogonial cells to meiotic and post-meiotic stages and sperm generation. Normal spermatogenesis occurs in vivo at 34 °C to 35 °C, and high temperatures are known to cause male infertility. The aim of the present study was to examine the effect of temperature (35 °C compared to 37 °C) on the viability/apoptosis of developed cells, on the development of different stages of spermatogenesis in 3D in vitro culture conditions, and the functionality of Sertoli cells under these conditions. We used isolated cells from seminiferous tubules of sexually immature mice. The cells were cultured in methylcellulose (as a three-dimensional (3D) in vitro culture system) and incubated in a CO2 incubator at 35 °C or 37 °C. After two to six weeks, the developed cells and organoids were collected and examined for cell viability and apoptosis markers. The development of different stages of spermatogenesis was evaluated by immunofluorescence staining or qPCR analysis using specific antibodies or primers, respectively, for cells at each stage. Factors that indicate the functionality of Sertoli cells were assessed by qPCR analysis. The developed organoids were examined by a confocal microscope. Our results show that the percentages and/or the expression levels of the developed pre-meiotic, meiotic, and post-meiotic cells were significantly higher at 35 °C compared to those at 37 °C, including the expression levels of the androgen receptor, the FSH receptor, transferrin, the androgen-binding protein (ABP), and the glial-derived nerve growth factor (GDNF) which were similarly significantly higher at 35 °C than at 37 °C. The percentages of apoptotic cells (according to acridine orange staining) and the expression levels of BAX, FAS, and CASPAS 3 were significantly higher in cultures incubated at 37 °C compared to those incubated at 35 °C. These findings support the in vivo results regarding the negative effect of high temperatures on the process of spermatogenesis and suggest a possible effect of high temperatures on the viability/apoptosis of spermatogenic cells. In addition, increasing the temperature in vitro also impaired the functionality of Sertoli cells. These findings may deepen our understanding of the mechanisms behind optimal conditions for normal spermatogenesis in vivo and in vitro.

Advances of three-dimensional (3D) culture systems for in vitro spermatogenesis

The loss of germ cells and spermatogenic failure in non-obstructive azoospermia are believed to be the main causes of male infertility. Laboratory studies have used in vitro testicular models and different 3-dimensional (3D) culture systems for preservation, proliferation and differentiation of spermatogonial stem cells (SSCs) in recent decades. The establishment of testis-like structures would facilitate the study of drug and toxicity screening, pathological mechanisms and in vitro differentiation of SSCs which resulted in possible treatment of male infertility. The different culture systems using cellular aggregation with self-assembling capability, the use of different natural and synthetic biomaterials and various methods for scaffold fabrication provided a suitable 3D niche for testicular cells development. Recently, 3D culture models have noticeably used in research for their architectural and functional similarities to native microenvironment. In this review article, we briefly investigated the recent 3D culture systems that provided a suitable platform for male fertility preservation through organ culture of testis fragments, proliferation and differentiation of SSCs.

Effect of Granulocyte Colony-Stimulating Factor on the Development of Spermatogenesis in the Adulthood of Juvenile AML Mice Model Treated with Cytarabine

Pediatric acute myeloid leukemia (AML) generally occurs de novo. The treatment of AML includes cytarabine (CYT) and other medications. The granulocyte-colony stimulating factor (GCSF) is used in the clinic in cases of neutropenia after chemotherapies. We show that the administration of GCSF in combination with CYT in AML-diagnosed mice (AML+CYT+GCSF) extended the survival of mice for additional 20 days. However, including GCSF in all treatment modalities does not affect the testis' weight or the histology of the seminiferous tubules (STs). We show that GCSF does not affect normal ST histology from AML-, CYT-, or (AML+CYT)-treated groups compared to the relevant treated group without GCSF 2, 4, and 5 weeks post-injection. However, when comparing the percentages of normal STs between the AML+CYT+GCSF-treated groups and those without GCSF, we observe an increase of 17%-42% in STs at 4 weeks and 5.5 weeks post-injection. Additionally, we show that the injection of GCSF into the normal, AML-alone, or CYT-alone groups, or in combination with AML, significantly decreases the percentage of STs with apoptotic cells compared to the relevant groups without GCSF and to the CT (untreated mice) only 2 weeks post-injection. We also show that injection of GCSF into the CT group increases the examined spermatogonial marker PLZF within 2 weeks post-injection. However, GCSF does not affect the count of meiotic cells (CREM) but decreases the post-meiotic cells (ACROSIN) within 4 weeks post-injection. Furthermore, GCSF not only extends the survival of the AML+CYT-treated group, but it also leads to the generation of sperm (1.2 ± 0.04 × 106/mL) at 5.5 weeks post-injection. In addition, we demonstrate that the injection of GCSF into the CT group increases the RNA expression level of IL-10 but not IL-6 compared to CT 2 weeks post-treatment. However, the injection of GCSF into the AML-treated group reverses the expression levels of both IL-10 and IL-6 to normal levels compared to CT 2 weeks post-injection. Thus, we suggest that the addition of GCSF to the regimen of AML after CYT may assist in the development of future therapeutic strategies to preserve male fertility in AML prepubertal patients.

Fertility preservation in pediatric healthcare: a review

Survival rates for children and adolescents diagnosed with malignancy have been steadily increasing due to advances in oncology treatments. These treatments can have a toxic effect on the gonads. Currently, oocyte and sperm cryopreservation are recognized as well-established and successful strategies for fertility preservation for pubertal patients, while the use of gonadotropin-releasing hormone agonists for ovarian protection is controversial. For prepubertal girls, ovarian tissue cryopreservation is the sole option. However, the endocrinological and reproductive outcomes after ovarian tissue transplantation are highly heterogeneous. On the other hand, immature testicular tissue cryopreservation remains the only alternative for prepubertal boys, yet it is still experimental. Although there are several published guidelines for navigating fertility preservation for pediatric and adolescent patients as well as transgender populations, it is still restricted in clinical practice. This review aims to discuss the indications and clinical outcomes of fertility preservation. We also discuss the probably effective and efficient workflow to facilitate fertility preservation.

In vitro complete differentiation of human spermatogonial stem cells to morphologic spermatozoa using a hybrid hydrogel of agarose and laminin

Spermatogenesis refers to the differentiation of the spermatogonial stem cells (SSCs) located in the base seminiferous tubules into haploid spermatozoa. Prerequisites for in vitro spermatogenesis include an extracellular matrix (ECM), paracrine factors, and testicular somatic cells which play a supporting role for SSCs. Thus, the present study evaluated the potential of co-culturing Sertoli cells and SSCs embedded in a hybrid hydrogel of agarose and laminin, the main components of the ECM. Following the three-week conventional culture of human testicular cells, the cells were cultured in agarose hydrogel or agarose/laminin one (hybrid) for 74 days. Then, immunocytochemistry, real-time PCR, electron microscopy, and morphological staining methods were applied to analyze the presence of SSCs, as well as the other cells of the different stages of spermatogenesis. Based on the results, the colonies with positive spermatogenesis markers were observed in both culture systems. The existence of the cells of all three phases of spermatogenesis (spermatogonia, meiosis, and spermiogenesis) was confirmed in the two groups, while morphological spermatozoa were detected only in the hybrid hydrogel group. Finally, a biologically improved 3D matrix can support all the physiological activities of SSCs such as survival, proliferation, and differentiation.

The Role of Promyelocytic Leukemia Zinc Finger (PLZF) and Glial-Derived Neurotrophic Factor Family Receptor Alpha 1 (GFRα1) in the Cryopreservation of Spermatogonia Stem Cells

The cryopreservation of spermatogonia stem cells (SSCs) has been widely used as an alternative treatment for infertility. However, cryopreservation itself induces cryoinjury due to oxidative and osmotic stress, leading to reduction in the survival rate and functionality of SSCs. Glial-derived neurotrophic factor family receptor alpha 1 (GFRα1) and promyelocytic leukemia zinc finger (PLZF) are expressed during the self-renewal and differentiation of SSCs, making them key tools for identifying the functionality of SSCs. To the best of our knowledge, the involvement of GFRα1 and PLZF in determining the functionality of SSCs after cryopreservation with therapeutic intervention is limited. Therefore, the purpose of this review is to determine the role of GFRα1 and PLZF as biomarkers for evaluating the functionality of SSCs in cryopreservation with therapeutic intervention. Therapeutic intervention, such as the use of antioxidants, and enhancement in cryopreservation protocols, such as cell encapsulation, cryoprotectant agents (CPA), and equilibrium of time and temperature increase the expression of GFRα1 and PLZF, resulting in maintaining the functionality of SSCs. In conclusion, GFRα1 and PLZF have the potential as biomarkers in cryopreservation with therapeutic intervention of SSCs to ensure the functionality of the stem cells.

Determining the expression levels of CSF-1 and OCT4, CREM-1, and protamine in testicular biopsies of adult Klinefelter patients: Their possible correlation with spermatogenesis

Klinefelter syndrome (KS) is the most prevalent genetic disorder of infertile males. This study aimed to determine in Klinefelter patients (KS) the expression levels of spermatogenic markers and testicular growth factors that might predict spermatogenesis based on conventional testicular sperm extraction (TESE). The expression levels of the pre-meiotic (OCT4, CD9, GFR-α1, α-6-INTEGRIN, SALL4, C-KIT), meiotic (CREM-1), and post-meiotic (protamine) markers, as well as the colony stimulating factor-1 (CSF-1) were examined in testicular biopsies with and without mature sperm of KS and normal karyotype of azoospermic patients (AZO) with complete spermatogenesis. In the biopsies of AZO, the expression levels (fold of expression compared to the PPI of the same sample) of OCT4 were 9.68± 7.93, CREM 42.78± 28.22, CSF-1 3.07 ± 3.19, and protamine 78498.12 ± 73214.40. Biopsies from KS included 7 with sperm and 17 without sperm. Among the biopsies with sperm, the expression levels of OCT4 were 7.27± 9.29, CREM 3.13± 7.89, CSF-1 35.5 ± 48.01, and protamine 902.97 ± 2365.92. In 14 biopsies without sperm, we found low expression levels of OCT4, CREM and CSF-1, and no expression of protamine. However, in three of the biopsies without sperm that highly expressed OCT4 and CSF-1, the expression levels of CREM-1 and protamine were high. These results may be used for further consulting with patients considering repeating conventional TESE or micro TESE and cryopreservation for possible future in-vitro spermatogenesis.

What should be done in terms of fertility preservation for patients with cancer? The French 2021 guidelines

AIM

To provide practice guidelines about fertility preservation (FP) in oncology.

METHODS

We selected 400 articles after a PubMed review of the literature (1987-2019).

RECOMMENDATIONS

Any child, adolescent and adult of reproductive age should be informed about the risk of treatment gonadotoxicity. In women, systematically proposed FP counselling between 15 and 38 years of age in case of treatment including bifunctional alkylating agents, above 6 g/m2 cyclophosphamide equivalent dose (CED), and for radiation doses on the ovaries ≥3 Gy. For postmenarchal patients, oocyte cryopreservation after ovarian stimulation is the first-line FP technique. Ovarian tissue cryopreservation should be discussed as a first-line approach in case of treatment with a high gonadotoxic risk, when chemotherapy has already started and in urgent cases. Ovarian transposition is to be discussed prior to pelvic radiotherapy involving a high risk of premature ovarian failure. For prepubertal girls, ovarian tissue cryopreservation should be proposed in the case of treatment with a high gonadotoxic risk. In pubertal males, sperm cryopreservation must be systematically offered to any male who is to undergo cancer treatment, regardless of toxicity. Testicular tissue cryopreservation must be proposed in males unable to cryopreserve sperm who are to undergo a treatment with intermediate or severe risk of gonadotoxicity. In prepubertal boys, testicular tissue preservation is: - recommended for chemotherapy with a CED ≥7500 mg/m2 or radiotherapy ≥3 Gy on both testicles. - proposed for chemotherapy with a CED ≥5.000 mg/m2 or radiotherapy ≥2 Gy. If several possible strategies, the ultimate choice is made by the patient.

New Entity-Thalassemic Endocrine Disease: Major Beta-Thalassemia and Endocrine Involvement

Beta-thalassemia (BTH), a recessively inherited haemoglobin (Hb) disorder, causes iron overload (IO), extra-medullary haematopoiesis and bone marrow expansion with major clinical impact. The main objective of this review is to address endocrine components (including aspects of reproductive health as fertility potential and pregnancy outcome) in major beta-thalassemia patients, a complex panel known as thalassemic endocrine disease (TED). We included English, full-text articles based on PubMed research (January 2017–June 2022). TED includes hypogonadism (hypoGn), anomalies of GH/IGF1 axes with growth retardation, hypothyroidism (hypoT), hypoparathyroidism (hypoPT), glucose profile anomalies, adrenal insufficiency, reduced bone mineral density (BMD), and deterioration of microarchitecture with increased fracture risk (FR). The prevalence of each ED varies with population, criteria of definition, etc. At least one out of every three to four children below the age of 12 y have one ED. ED correlates with ferritin and poor compliance to therapy, but not all studies agree. Up to 86% of the adult population is affected by an ED. Age is a positive linear predictor for ED. Low IGF1 is found in 95% of the population with GH deficiency (GHD), but also in 93.6% of persons without GHD. HypoT is mostly pituitary-related; it is not clinically manifested in the majority of cases, hence the importance of TSH/FT4 screening. HypoT is found at any age, with the prevalence varying between 8.3% and 30%. Non-compliance to chelation increases the risk of hypoT, yet not all studies confirmed the correlation with chelation history (reversible hypoT under chelation is reported). The pitfalls of TSH interpretation due to hypophyseal IO should be taken into consideration. HypoPT prevalence varies from 6.66% (below the age of 12) to a maximum of 40% (depending on the study). Serum ferritin might act as a stimulator of FGF23. Associated hypocalcaemia transitions from asymptomatic to severe manifestations. HypoPT is mostly found in association with growth retardation and hypoGn. TED-associated adrenal dysfunction is typically mild; an index of suspicion should be considered due to potential life-threatening complications. Periodic check-up by ACTH stimulation test is advised. Adrenal insufficiency/hypocortisolism status is the rarest ED (but some reported a prevalence of up to one third of patients). Significantly, many studies did not routinely perform a dynamic test. Atypical EM sites might be found in adrenals, mimicking an incidentaloma. Between 7.5–10% of children with major BTH have DM; screening starts by the age of 10, and ferritin correlated with glycaemia. Larger studies found DM in up to 34%of cases. Many studies do not take into consideration IGF, IGT, or do not routinely include OGTT. Glucose anomalies are time dependent. Emerging new markers represent promising alternatives, such as insulin secretion-sensitivity index-2. The pitfalls of glucose profile interpretation include the levels of HbA1c and the particular risk of gestational DM. Thalassemia bone disease (TBD) is related to hypoGn-related osteoporosis, renal function anomalies, DM, GHD, malnutrition, chronic hypoxia-induced calcium malabsorption, and transplant-associated protocols. Low BMD was identified in both paediatric and adult population; the prevalence of osteoporosis/TBD in major BTH patients varies; the highest rate is 40–72% depending on age, studied parameters, DXA evaluation and corrections, and screening thoracic–lumbar spine X-ray. Lower TBS and abnormal dynamics of bone turnover markers are reported. The largest cohorts on transfusion-dependent BTH identified the prevalence of hypoGn to be between 44.5% and 82%. Ferritin positively correlates with pubertal delay, and negatively with pituitary volume. Some authors appreciate hypoGn as the most frequent ED below the age of 15. Long-term untreated hypoGn induces a high cardiovascular risk and increased FR. Hormonal replacement therapy is necessary in addition to specific BTH therapy. Infertility underlines TED-related hormonal elements (primary and secondary hypoGn) and IO-induced gonadal toxicity. Males with BTH are at risk of infertility due to germ cell loss. IO induces an excessive amount of free radicals which impair the quality of sperm, iron being a local catalyser of ROS. Adequate chelation might improve fertility issues. Due to the advances in current therapies, the reproductive health of females with major BTH is improving; a low level of statistical significance reflects the pregnancy status in major BTH (limited data on spontaneous pregnancies and growing evidence of the induction of ovulation/assisted reproductive techniques). Pregnancy outcome also depends on TED approach, including factors such as DM control, adequate replacement of hypoT and hypoPT, and vitamin D supplementation for bone health. Asymptomatic TED elements such as subclinical hypothyroidism or IFG/IGT might become overt during pregnancy. Endocrine glands are particularly sensitive to iron deposits, hence TED includes a complicated puzzle of EDs which massively impacts on the overall picture, including the quality of life in major BTH. The BTH prognostic has registered progress in the last decades due to modern therapy, but the medical and social burden remains elevated. Genetic counselling represents a major step in approaching TH individuals, including as part of the pre-conception assessment. A multidisciplinary surveillance team is mandatory.

In vitro production of mouse morphological sperm in artificial testis bioengineered by 3D printing of extracellular matrix

Since autologous stem cell transplantation is prone to cancer recurrence, in vitro sperm production is regarded a safer approach to fertility preservation. In this study, the spermatogenesis process on testicular tissue extracellular matrix (T-ECM)-derived printing structure was evaluated. Ram testicular tissue was decellularized using a hypertonic solution containing triton and the extracted ECM was used as a bio-ink to print an artificial testis. Following cell adhesion and viability examination, pre-meiotic and post-meiotic cells in the study groups (as testicular suspension and co-culture with Sertoli cells) were confirmed by real-time PCR, flow-cytometry and immunocytochemistry methods. Morphology of differentiated cells was evaluated using transmission electron microscopy (TEM), toluidine blue, Giemsa, and hematoxylin and eosin (H&E) staining. The functionality of Leydig and Sertoli cells was determined by their ability for hormone secretion. The decellularization of testicular tissue fragments was successful and had efficiently removed the cellular debris and preserved the ECM compounds. High cell viability, colonization, and increased expression of pre-meiotic markers in cultured testicular cells on T-ECM-enriched scaffolds confirmed their proliferation. Furthermore, the inoculation of neonatal mouse testicular cells onto T-ECM-enriched scaffolds resulted in the generation of sperm. Morphology evaluation showed that the structure of these cells was quite similar to mature sperm with a specialized tail structure. The hormonal analysis also confirmed production and secretion of testosterone and inhibin B by Leydig and Sertoli cells. T-ECM printed artificial testis is a future milestone that promises for enhancing germ cell maintenance and differentiation, toxicology studies, and fertility restoration to pave the way for new human infertility treatments in the future.

Microfluidic and Static Organotypic Culture Systems to Support Ex Vivo Spermatogenesis From Prepubertal Porcine Testicular Tissue: A Comparative Study

Background:In vitro maturation of immature testicular tissue (ITT) cryopreserved for fertility preservation is a promising fertility restoration strategy. Organotypic tissue culture proved successful in mice, leading to live births. In larger mammals, including humans, efficiently reproducing spermatogenesis ex vivo remains challenging. With advances in biomaterials technology, culture systems are becoming more complex to better mimic in vivo conditions. Along with improving culture media components, optimizing physical culture conditions (e.g., tissue perfusion, oxygen diffusion) also needs to be considered. Recent studies in mice showed that by using silicone-based hybrid culture systems, the efficiency of spermatogenesis can be improved. Such systems have not been reported for ITT of large mammals.

Methods: Four different organotypic tissue culture systems were compared: static i.e., polytetrafluoroethylene membrane inserts (OT), agarose gel (AG) and agarose gel with polydimethylsiloxane chamber (AGPC), and dynamic i.e., microfluidic (MF). OT served as control. Porcine ITT fragments were cultured over a 30-day period using a single culture medium. Analyses were performed at days (d) 0, 5, 10, 20 and 30. Seminiferous tubule (ST) integrity, diameters, and tissue core integrity were evaluated on histology. Immunohistochemistry was used to identify germ cells (PGP9.5, VASA, SYCP3, CREM), somatic cells (SOX9, INSL3) and proliferating cells (Ki67), and to assess oxidative stress (MDA) and apoptosis (C-Caspase3). Testosterone was measured in supernatants using ELISA.

Results: ITT fragments survived and grew in all systems. ST diameters, and Sertoli cell (SOX9) numbers increased, meiotic (SYCP3) and post-meiotic (CREM) germ cells were generated, and testosterone was secreted. When compared to control (OT), significantly larger STs (d10 through d30), better tissue core integrity (d5 through d20), higher numbers of undifferentiated spermatogonia (d30), meiotic and post-meiotic germ cells (SYCP3: d20 and 30, CREM: d20) were observed in the AGPC system. Apoptosis, lipid peroxidation (MDA), ST integrity, proliferating germ cell (Ki67/VASA) numbers, Leydig cell (INSL3) numbers and testosterone levels were not significantly different between systems.

Conclusions: Using a modified culture system (AGPC), germ cell survival and the efficiency of porcine germ cell differentiation were moderately improved ex vivo. We assume that further optimization can be obtained with concomitant modifications in culture media components.

Achievement of complete in vitro spermatogenesis in testicular tissues from prepubertal mice exposed to mono- or polychemotherapy

The assessment of the impact of chemotherapies on in vitro spermatogenesis in experimental models is required before considering the application of this fertility restoration strategy to prepubertal boys who received these treatments before testicular tissue cryopreservation. The present work investigated the effects of exposure of prepubertal mice to mono- (vincristine or cyclophosphamide) and polychemotherapy (a combination of vincristine and cyclophosphamide) on the first wave of in vitro spermatogenesis. When testicular tissue exposed to monochemotherapy was preserved, polychemotherapy led to severe alterations of the seminiferous epithelium and increased apoptosis in prepubertal testes prior in vitro maturation, suggesting a potential additive gonadotoxic effect. These alterations were also found in the testicular tissues of polychemotherapy-treated mice after 30 days of organotypic culture and were associated with a reduction in the germ cell/Sertoli cell ratio. The different treatments neither altered the ability of spermatogonia to differentiate in vitro into spermatozoa nor the yield of in vitro spermatogenesis. However, more spermatozoa with morphological abnormalities and fragmented DNA were produced after administration of polychemotherapy. This work therefore shows for the first time the possibility to achieve a complete in vitro spermatogenesis after an in vivo exposure of mice to a mono- or polychemotherapy before meiotic entry.

Effect of Chemotherapy Cytarabine and Acute Myeloid Leukemia on the Development of Spermatogenesis at the Adult Age of Immature Treated Mice

Acute myeloid leukemia (AML) accounts for around 20% of diagnosed childhood leukemia. Cytarabine (CYT) is involved in the AML treatment regimen. AML and CYT showed impairment in spermatogenesis in human and rodents in adulthood. We successfully developed an AML disease model in sexually immature mice. Monocytes and granulocytes were examined in all groups: untreated control, AML alone, CYT alone and AML+CYT (in combination). There was a significant increase in the counts of monocytes and granulocytes in the AML-treated immature mice (AML) compared to the control, and AML cells were demonstrated in the blood vessels of the testes. AML alone and CYT alone impaired the development of spermatogenesis at the adult age of the AML-treated immature mice. The damage was clear in the structure/histology of their seminiferous tubules, and an increase in the apoptotic cells of the seminiferous tubules was demonstrated. Our results demonstrated a significant decrease in the meiotic/post-meiotic cells compared to the control. However, CYT alone (but not AML) significantly increased the count of spermatogonial cells (premeiotic cells) that positively stained with SALL4 and PLZF per tubule compared to the control. Furthermore, AML significantly increased the count of proliferating spermatogonial cells that positively stained with PCNA in the seminiferous tubules compared to the control, whereas CYT significantly decreased the count compared to the control. Our result showed that AML and CYT affected the microenvironment/niche of the germ cells. AML significantly decreased the levels growth factors, such as SCF, GDNF and MCSF) compared to control, whereas CYT significantly increased the levels of MCSF and GDNF compared to control. In addition, AML significantly increased the RNA expression levels of testicular IL-6 (a proinflammatory cytokine), whereas CYT significantly decreased testicular IL-6 levels compared to the control group. Furthermore, AML alone and CYT alone significantly decreased RNA expression levels of testicular IL-10 (anti-inflammatory cytokine) compared to the control group. Our results demonstrate that pediatric AML disease with or without CYT treatment impairs spermatogenesis at adult age (the impairment was more pronounced in AML+CYT) compared to control. Thus, we suggest that special care should be considered for children with AML who are treated with a CYT regimen regarding their future fertility at adult age.

Testis on a chip - a microfluidic 3-dimensional culture system for the development of spermatogenesisin-vitro

This research presents a novel Testis-on-a Chip- platform. Testicular cells are enzymatically isolated from the seminiferous tubules of sexually immature mice, seeded in a methylcellulose gel and cultured in a microfluidic chip. The unique design sandwiches the soft methylcellulose between stiffer agar support gels. The cells develop into organoids continuing to proliferate and differentiate. After seven weeks of culture the cells have over 95% viability. Confocal microscopy of the developed organoids reveals a structure containing the various stages of spermatogenesis up to and including meiosis II: premeiotic, meiotic and post-meiotic germ cells. The organoid structure also contains the supporting Sertoli and peritubular cells. The responsiveness of the system to the addition of testosterone and retinoic acid to the culture medium during the experiment are also investigated. As a benchmark, the Testis-on-a-Chip is compared to a conventional three-dimensional methylcellulose cell culture in a well plate. Analysis via FACS (Fluorescence-activated cell sorting) shows more haploid cells in the chip as compared to the plates. Immunofluorescence staining after seven weeks of culture shows more differentiated cells in the chip as compared to the well plate. This demonstrates the feasibility of our platform as well as its advantages. This research opens new horizons for the study and realization of spermatogenesis in-vitro. It can also enable the implementation of microfluidic technologies in future therapeutic strategies for pre pubertal male fertility preservation and adults with maturation arrest. Lastly, it can serve as a platform for drug and toxin testing.

Fertility Preservation and Restoration Options for Pre-Pubertal Male Cancer Patients: Current Approaches

Fertility preservation for prepubertal male patients undergoing gonadotoxic therapies, potentially depleting spermatogonial cells, is an expanding necessity, yet most of the feasible options are still in the experimental phase. We present our experience and a summary of current and novel possibilities regarding the different strategies to protect or restore fertility in young male patients, before proceeding with chemotherapy or radiotherapy for malignances or other diseases. Adult oncological patients should always be counselled to cryopreserve the semen before starting treatment, however this approach is not suitable for prepubertal boys, who aren't capable to produce sperm yet. Fortunately, since the survival rate of pediatric cancer patients has skyrocketed in the last decade and it's over 84%, safeguarding their future fertility is becoming a major concern for reproductive medicine. Surgical and medical approaches to personalize treatment or protect the gonads could be a valid first step to take. Testicular tissue autologous grafting or xenografting, and spermatogonial stem cells (SSCs) transplantation, are the main experimental options available, but spermatogenesis in vitro is becoming an intriguing alternative. All of these methods feature both strong and weak prospects. There is also relevant controversy regarding the type of testicular material to preserve and the cryopreservation methods. Since transplanted cells are bound to survive based on SSCs number, many ways to enrich their population in cultures have been proposed, as well as different sites of injection inside the testis. Testicular tissue graft has been experimented on mice, rabbits, rhesus macaques and porcine, allowing the birth of live offspring after performing intracytoplasmic sperm injection (ICSI), however it has never been performed on human males yet. In vitro spermatogenesis remains a mirage, although many steps in the right direction have been performed. The manufacturing of 3D scaffolds and artificial spermatogenetic niche, providing support to stem cells in cultures, seems like the best way to further advance in this field.

POSTN Promotes the Proliferation of Spermatogonial Cells by Activating the Wnt/β-Catenin Signaling Pathway

The self-renewal of spermatogonial cells (SCs) provides the foundation for life-long spermatogenesis. To date, only a few growth factors have been used for the culture of SCs in vitro, and how to enhance proliferation capacity of SCs in vitro needs further research. This study aimed to explore the effects of periostin (POSTN) on the proliferation of human SCs. GC-1 spg cells were cultured in a medium with POSTN, cell proliferation was evaluated by MTS analysis and EdU assay, and the Wnt/β-catenin signaling pathway was examined. Thereafter, the proliferations of human SC were detected using immunofluorescence and RT-PCR. In this study, we found that CM secreted by human amniotic mesenchymal stem cells (hAMSCs) could enhance the proliferation capacity of mouse GC-1 spg cells. Label-free mass spectrometry and ELISA analysis demonstrated that high level of POSTN was secreted by hAMSCs. MTS and EdU staining showed that POSTN increased GC-1 spg cell proliferation, whereas CM from POSTN-silenced hAMSCs suppressed cell proliferation capacity. Then POSTN was found to activate the Wnt/β-catenin signaling pathway to regulate the proliferation of GC-1 spg cells. XAV-939, a Wnt/β-catenin inhibitor, partially reversed the effects of POSTN on GC-1 spg cell proliferation. We then analyzed human SCs and found that POSTN promoted human SC proliferation in vitro. These findings provide insights regarding the role of POSTN in regulating SC proliferation via the Wnt/β-catenin signaling pathway and suggest that POSTN may serve as a cytokine for male infertility therapy.

The Presence of Colony-Stimulating Factor-1 and Its Receptor in Different Cells of the Testis; It Involved in the Development of Spermatogenesis In Vitro

Spermatogenesis is a complex process, in which spermatogonial cells proliferate and differentiate in the seminiferous tubules of the testis to generate sperm. This process is under the regulation of endocrine and testicular paracrine/autocrine factors. In the present study, we demonstrated that colony stimulating factor-1 (CSF-1) is produced by mouse testicular macrophages, Leydig, Sertoli, peritubular cells and spermatogonial cells (such as CDH1-positively stained cells; a marker of spermatogonial cells). In addition, we demonstrated the presence of CSF-1 and its receptor (CSF-1R) in testicular macrophages, Leydig, Sertoli, peritubular cells and spermatogonial cells of human testis. We also show that the protein levels of CSF-1 were the highest in testis of 1-week-old mice and significantly decreased with age (2–12-week-old). However, the transcriptome levels of CSF-1 significantly increased in 2–3-week-old compared to 1-week-old, and thereafter significantly decreased with age. On the other hand, the transcriptome levels of CSF-1R was significantly higher in mouse testicular tissue of all examined ages (2–12-week-old) compared to 1-week-old. Our results demonstrate the involvement of CSF-1 in the induction the proliferation and differentiation of spermatogonial cells to meiotic and postmeiotic stages (BOULE- and ACROSIN-positive cells) under in vitro culture conditions, using methylcellulose culture system (MCS). Thus, it is possible to suggest that CSF-1 system, as a testicular paracrine/autocrine system, is involved in the development of different stages of spermatogenesis and may be used in the development of future therapeutic strategies for treatment of male infertility.

Involvement of Cytokines and Hormones in the Development of Spermatogenesis In Vitro from Spermatogonial Cells of Cyclophosphamide-Treated Immature Mice

Aggressive chemotherapy treatment may lead to male infertility. Prepubertal boys do not produce sperm at this age, however, they have spermatogonial stem cells in their testes. Here, we examined the effect of intraperitoneal injection of cyclophosphamide (CP) on the capacity of immature mice (IM) to develop spermatogenesis in vivo and in vitro [using methylcellulose culture system (MCS)]. Our results show a significant decrease in testicular weight, total number of testicular cells, and the number of Sertoli, peritubular, premeiotic, and meiotic/post-meiotic cells, but an increase in the percentages of damaged seminiferous tubules in CP-treated IM compared to control. The functionality of Sertoli cells was significantly affected. The addition of testosterone to isolated cells from seminiferous tubules of CP-treated IM significantly increased the percentages of premeiotic (CD9-positive cells) and meiotic/post-meiotic cells (ACROSIN-positive cells) developed in MCS compared to control. The addition of FSH did not affect developed cells in MCS compared to control, but in combination with testosterone, it significantly decreased the percentages of CD9-positive cells and ACROSIN-positive cells. The addition of IL-1 did not affect developed cells in MCS compared to control, but in combination with testosterone, it significantly increased the percentages of VASA-positive cells and BOULE-positive cells compared to IL-1 or testosterone. Addition of TNF significantly increased only CD9-positive cells in MCS compared to control, but in combination with testosterone, it significantly decreased ACROSIN-positive cells compared to testosterone. Our results show a significant impairment of spermatogenesis in the testes of CP-treated IM, and that spermatogonial cells from these mice proliferate and differentiate to meiotic/post-meiotic cells under in vitro culture conditions.

The Expression Levels and Cellular Localization of Pigment Epithelium Derived Factor (PEDF) in Mouse Testis: Its Possible Involvement in the Differentiation of Spermatogonial Cells

Pigment epithelium derived factor (PEDF) is a multifunctional secretory soluble glycoprotein that belongs to the serine protease inhibitor (serpin) family. It was reported to have neurotrophic, anti-angiogenic and anti-tumorigenic activity. Recently, PEDF was found in testicular peritubular cells and it was assumed to be involved in the avascular nature of seminiferous tubules. The aim of this study was to determine the cellular origin, expression levels and target cells of PEDF in testicular tissue of immature and adult mice under physiological conditions, and to explore its possible role in the process of spermatogenesis in vitro. Using immunofluorescence staining, we showed that PEDF was localized in spermatogenic cells at different stages of development as well as in the somatic cells of the testis. Its protein levels in testicular homogenates and Sertoli cells supernatant showed a significant decrease with age. PEDF receptor (PEDF-R) was localized within the seminiferous tubule cells and in the interstitial cells compartment. Its RNA expression levels showed an increase with age until 8 weeks followed by a decrease. RNA levels of PEDF-R showed the opposite trend of the protein. Addition of PEDF to cultures of isolated cells from the seminiferous tubules did not changed their proliferation rate, however, a significant increase was observed in number of meiotic/post meiotic cells at 1000 ng/mL of PEDF; indicating an in vitro differentiation effect. This study may suggest a role for PEDF in the process of spermatogenesis.

Fertility preservation for prepubertal boys: lessons learned from the past and update on remaining challenges towards clinical translation

BACKGROUND

Childhood cancer incidence and survivorship are both on the rise. However, many lifesaving treatments threaten the prepubertal testis. Cryopreservation of immature testicular tissue (ITT), containing spermatogonial stem cells (SSCs), as a fertility preservation (FP) option for this population is increasingly proposed worldwide. Recent achievements notably the birth of non-human primate (NHP) progeny using sperm developed in frozen-thawed ITT autografts has given proof of principle of the reproductive potential of banked ITT. Outlining the current state of the art on FP for prepubertal boys is crucial as some of the boys who have cryopreserved ITT since the early 2000s are now in their reproductive age and are already seeking answers with regards to their fertility.

OBJECTIVE AND RATIONALE

In the light of past decade achievements and observations, this review aims to provide insight into relevant questions for clinicians involved in FP programmes. Have the indications for FP for prepubertal boys changed over time? What is key for patient counselling and ITT sampling based on the latest achievements in animals and research performed with human ITT? How far are we from clinical application of methods to restore reproductive capacity with cryostored ITT?

SEARCH METHODS

An extensive search for articles published in English or French since January 2010 to June 2020 using keywords relevant to the topic of FP for prepubertal boys was made in the MEDLINE database through PubMed. Original articles on fertility preservation with emphasis on those involving prepubertal testicular tissue, as well as comprehensive and systematic reviews were included. Papers with redundancy of information or with an absence of a relevant link for future clinical application were excluded. Papers on alternative sources of stem cells besides SSCs were excluded.

OUTCOMES

Preliminary follow-up data indicate that around 27% of boys who have undergone testicular sampling as an FP measure have proved azoospermic and must therefore solely rely on their cryostored ITT to ensure biologic parenthood. Auto-transplantation of ITT appears to be the first technique that could enter pilot clinical trials but should be restricted to tissue free of malignant cells. While in vitro spermatogenesis circumvents the risk linked to cancer cell contamination and has led to offspring in mice, complete spermatogenesis has not been achieved with human ITT. However, generation of haploid germ cells paves the way to further studies aimed at completing the final maturation of germ cells and increasing the efficiency of the processes.

WIDER IMPLICATIONS

Despite all the research done to date, FP for prepubertal boys remains a relatively young field and is often challenging to healthcare providers, patients and parents. As cryopreservation of ITT is now likely to expand further, it is important not only to acknowledge some of the research questions raised on the topic, e.g. the epigenetic and genetic integrity of gametes derived from strategies to restore fertility with banked ITT but also to provide healthcare professionals worldwide with updated knowledge to launch proper multicollaborative care pathways in the field and address clinical issues that will come-up when aiming for the child's best interest.

Interleukin-34, a Novel Paracrine/Autocrine Factor in Mouse Testis, and Its Possible Role in the Development of Spermatogonial Cells In Vitro

Spermatogenesis is the process of spermatogonial stem cell (SSC) proliferation and differentiation to generate sperm. This process is regulated by cell–cell interactions between Sertoli cells and developing SSCs by autocrine/paracrine and endocrine factors. It is also affected by cells in the interstitial compartment, such as Leydig cells and peritubular cells. Here, we demonstrate, for the first time, the presence of interleukin-34 (IL-34) in Leydig, Sertoli, and peritubular cells and in the premeiotic, meiotic, and postmeiotic cells. Its receptor, colony-stimulating factor-1 (CSF-1), has already been demonstrated in Leydig, Sertoli, premeiotic, and meiotic cells. IL-34 was detected in testicular homogenates and Sertoli cell-conditioned media, and was affected by mouse age. We showed that the addition of IL-34 in vitro to isolated cells from the seminiferous tubules of 7-day-old mice, using the methylcellulose culture system (MCS), increased the percentages and expression of the premeiotic cells (VASA), the meiotic cells (BOULE), and the meiotic/postmeiotic cells (ACROSIN) after four weeks of culture, when examined by immunofluorescence staining (IF) and qPCR analysis. It is possible to suggest that IL-34 is a novel paracrine/autocrine factor involved in the development of spermatogenesis. This factor may be used in future therapeutic strategies for the treatment of male infertility.

Stem cell-based therapies for fertility preservation in males: Current status and future prospects

With the decline in male fertility in recent years, strategies for male fertility preservation have received increasing attention. In this study, by reviewing current treatments and recent publications, we describe research progress in and the future directions of stem cell-based therapies for male fertility preservation, focusing on the use of spermatogonial stem cells (SSCs), SSC niches, SSC-based testicular organoids, other stem cell types such as mesenchymal stem cells, and stem cell-derived extracellular vesicles. In conclusion, a more comprehensive understanding of the germ cell microenvironment, stem cell-derived extracellular vesicles, and testicular organoids will play an important role in achieving male fertility preservation.

Absence of SCAPER causes male infertility in humans and Drosophila by modulating microtubule dynamics during meiosis

BACKGROUND

Mutation in S-phase cyclin A-associated protein rin the endoplasmic reticulum (SCAPER) have been found across ethnicities and have been shown to cause variable penetrance of an array of pathological traits, including intellectual disability, retinitis pigmentosa and ciliopathies.

METHODS

Human clinical phenotyping, surgical testicular sperm extraction and testicular tissue staining. Generation and analysis of short spindle 3 (ssp3) (SCAPER orthologue) Drosophila CAS9-knockout lines. In vitro microtubule (MT) binding assayed by total internal reflection fluorescence microscopy.

RESULTS

We show that patients homozygous for a SCAPER mutation lack SCAPER expression in spermatogonia (SPG) and are azoospermic due to early defects in spermatogenesis, leading to the complete absence of meiotic cells. Interestingly, Drosophila null mutants for the ubiquitously expressed ssp3 gene are viable and female fertile but male sterile. We further show that male sterility in ssp3 null mutants is due to failure in both chromosome segregation and cytokinesis. In cells undergoing male meiosis, the MTs emanating from the centrosomes do not appear to interact properly with the chromosomes, which remain dispersed within dividing spermatocytes (SPCs). In addition, mutant SPCs are unable to assemble a normal central spindle and undergo cytokinesis. Consistent with these results, an in vitro assay demonstrated that both SCAPER and Ssp3 directly bind MTs.

CONCLUSIONS

Our results show that SCAPER null mutations block the entry into meiosis of SPG, causing azoospermia. Null mutations in ssp3 specifically disrupt MT dynamics during male meiosis, leading to sterility. Moreover, both SCAPER and Ssp3 bind MTs in vitro. These results raise the intriguing possibility of a common feature between human and Drosophila meiosis.

Fertility preservation in boys: recent developments and new insights †

BACKGROUND

Infertility is an important side effect of treatments used for cancer and other non-malignant conditions in males. This may be due to the loss of spermatogonial stem cells (SSCs) and/or altered functionality of testicular somatic cells (e.g. Sertoli cells, Leydig cells). Whereas sperm cryopreservation is the first-line procedure to preserve fertility in post-pubertal males, this option does not exist for prepubertal boys. For patients unable to produce sperm and at high risk of losing their fertility, testicular tissue freezing is now proposed as an alternative experimental option to safeguard their fertility.

OBJECTIVE AND RATIONALE

With this review, we aim to provide an update on clinical practices and experimental methods, as well as to describe patient management inclusion strategies used to preserve and restore the fertility of prepubertal boys at high risk of fertility loss.

SEARCH METHODS

Based on the expertise of the participating centres and a literature search of the progress in clinical practices, patient management strategies and experimental methods used to preserve and restore the fertility of prepubertal boys at high risk of fertility loss were identified. In addition, a survey was conducted amongst European and North American centres/networks that have published papers on their testicular tissue banking activity.

OUTCOMES

Since the first publication on murine SSC transplantation in 1994, remarkable progress has been made towards clinical application: cryopreservation protocols for testicular tissue have been developed in animal models and are now offered to patients in clinics as a still experimental procedure. Transplantation methods have been adapted for human testis, and the efficiency and safety of the technique are being evaluated in mouse and primate models. However, important practical, medical and ethical issues must be resolved before fertility restoration can be applied in the clinic.Since the previous survey conducted in 2012, the implementation of testicular tissue cryopreservation as a means to preserve the fertility of prepubertal boys has increased. Data have been collected from 24 co-ordinating centres worldwide, which are actively offering testis tissue cryobanking to safeguard the future fertility of boys. More than 1033 young patients (age range 3 months to 18 years) have already undergone testicular tissue retrieval and storage for fertility preservation.

LIMITATIONS REASONS FOR CAUTION

The review does not include the data of all reproductive centres worldwide. Other centres might be offering testicular tissue cryopreservation. Therefore, the numbers might be not representative for the entire field in reproductive medicine and biology worldwide. The key ethical issue regarding fertility preservation in prepubertal boys remains the experimental nature of the intervention.

WIDER IMPLICATIONS

The revised procedures can be implemented by the multi-disciplinary teams offering and/or developing treatment strategies to preserve the fertility of prepubertal boys who have a high risk of fertility loss.

STUDY FUNDING/COMPETING INTERESTS

The work was funded by ESHRE. None of the authors has a conflict of interest.

Progress in translational reproductive science: testicular tissue transplantation and in vitro spermatogenesis

Since the birth of the first child conceived via in vitro fertilization 40 years ago, fertility treatments and assisted reproductive technology have allowed many couples to reach their reproductive goals. As of yet, no fertility options are available for men who cannot produce functional sperm, but many experimental therapies have demonstrated promising results in animal models. Both autologous (stem cell transplantation, de novo morphogenesis, and testicular tissue grafting) and outside-the-body (xenografting and in vitro spermatogenesis) approaches exist for restoring sperm production in infertile animals with varying degrees of success. Once safety profiles are established and an ideal patient population is chosen, some of these techniques may be ready for human experimentation in the near future, with likely clinical implementation within the next decade.

Exposure to Chemotherapy During Childhood or Adulthood and Consequences on Spermatogenesis and Male Fertility

Over the last decade, the number of cancer survivors has increased thanks to progress in diagnosis and treatment. Cancer treatments are often accompanied by adverse side effects depending on the age of the patient, the type of cancer, the treatment regimen, and the doses. The testicular tissue is very sensitive to chemotherapy and radiotherapy. This review will summarize the epidemiological and experimental data concerning the consequences of exposure to chemotherapy during the prepubertal period or adulthood on spermatogenic progression, sperm production, sperm nuclear quality, and the health of the offspring. Studies concerning the gonadotoxicity of anticancer drugs in adult survivors of childhood cancer are still limited compared with those concerning the effects of chemotherapy exposure during adulthood. In humans, it is difficult to evaluate exactly the toxicity of chemotherapeutic agents because cancer treatments often combine chemotherapy and radiotherapy. Thus, it is important to undertake experimental studies in animal models in order to define the mechanism involved in the drug gonadotoxicity and to assess the effects of their administration alone or in combination on immature and mature testis. These data will help to better inform cancer patients after recovery about the risks of chemotherapy for their future fertility and to propose fertility preservation options.

Testicular Function of Childhood Cancer Survivors: Who Is Worse?

Background: A multi-disciplinary approach has led to an improvement in prognosis of childhood cancers. However, in parallel with the increase in survival rate, there is a greater occurrence of long-term toxicity related to antineoplastic treatment. Hypogonadism and infertility are among the most frequent endocrinological sequelae in young adult childhood cancer survivors. The aim of this study was to identify which category of patients, grouped according to diagnosis, therapy, and age at treatment, shows the worst reproductive function in adulthood. Methods: We evaluated morpho-volumetric development of the testis, endocrine function of the hypothalamic–pituitary–gonadal axis, and sperm parameters in 102 young adult childhood cancer survivors. Results: Overall, about one-third of patients showed low total testicular volume, total testosterone (TT) <3.5 ng/mL, and altered sperm count. Hodgkin’s disease, hematopoietic stem cell transplantation, and non-cranial irradiation associated to chemotherapy were risk factors for poor gonadal function. Patients treated in pubertal age showed lower total testicular volume; however, the difference was due to more gonadotoxic treatment performed in older age. Testicular volume was more predictive of spermatogenesis than follicle-stimulating hormone (FSH), while anti-Müllerian hormone (AMH) was not useful in the evaluation of testicular function of male childhood cancer survivors. Conclusions: Pre-pubertal subjects at high risk of future infertility should be candidates for testicular tissue cryopreservation.

Generation of Organized Porcine Testicular Organoids in Solubilized Hydrogels from Decellularized Extracellular Matrix

Cryopreservation of immature testicular tissue (ITT) prior to chemo/radiotherapy is now ethically accepted and is currently the only way to preserve fertility of prepubertal boys about to undergo cancer therapies. So far, three-dimensional culture of testicular cells isolated from prepubertal human testicular tissue was neither efficient nor reproducible to obtain mature spermatozoa, and ITT transplantation is not a safe option when there is a risk of cancer cell contamination of the testis. Hence, generation of testicular organoids (TOs) after cell selection is a novel strategy aimed at restoring fertility in these patients. Here, we created TOs using hydrogels developed from decellularized porcine ITT and compared cell numbers, organization and function to TOs generated in collagen only hydrogel. Organotypic culture of porcine ITT was used as a control. Rheological and mass spectrometry analyses of both hydrogels highlighted differences in terms of extracellular matrix stiffness and composition, respectively. Sertoli cells (SCs) and germ cells (GCs) assembled into seminiferous tubule-like structures delimited by a basement membrane while Leydig cells (LCs) and peritubular cells localized outside. TOs were maintained for 45 days in culture and secreted stem cell factor and testosterone demonstrating functionality of SCs and LCs, respectively. In both TOs GC numbers decreased and SC numbers increased. However, LC numbers decreased significantly in the collagen hydrogel TOs (p < 0.05) suggesting a better preservation of growth factors within TOs developed from decellularized ITT and thus a better potential to restore the reproductive capacity.

Potential use of stem cells for fertility preservation

BACKGROUND

Infertility and gonadal dysfunction can result from gonadotoxic therapies, environmental exposures, aging, or genetic conditions. In men, non-obstructive azoospermia (NOA) results from defects in the spermatogenic process that can be attributed to spermatogonial stem cells (SSC) or their niche, or both. While assisted reproductive technologies and sperm banking can enable fertility preservation (FP) in men of reproductive age who are at risk for infertility, FP for pre-pubertal patients remains experimental. Therapeutic options for NOA are limited. The rapid advance of stem cell research and of gene editing technologies could enable new FP options for these patients. Induced pluripotent stem cells (iPSC), SSC, and testicular niche cells, as well as mesenchymal stromal cells (aka medicinal signaling cells, MSCs), have been investigated for their potential use in male FP strategies.

OBJECTIVE

Here, we review the benefits and challenges for three types of stem cell-based approaches under investigation for male FP, focusing on the role that promising sources of MSC derived from human umbilical cord, specifically human umbilical cord perivascular cells (HUCPVC), could fulfill. These approaches are as follows: 1. isolation and ex vivo expansion of autologous SSC for in vivo transplantation or in vitro spermatogenesis; 2. in vitro differentiation toward germ cell and testicular somatic cell lineages using autologous SSC, or stem cells such iPSC or MSC; and 3. protection or regeneration of the spermatogenic niche after gonadotoxic insults in vivo.

CONCLUSION

Our studies suggest that HUCPVC are promising sources of cells that could be utilized in multiple aspects of male FP strategies.

Role of stem cells in fertility preservation: current insights

While improvements made in the field of cancer therapy allow high survival rates, gonadotoxicity of chemo- and radiotherapy can lead to infertility in male and female pre- and postpubertal patients. Clinical options to preserve fertility before starting gonadotoxic therapies by cryopreserving sperm or oocytes for future use with assisted reproductive technology (ART) are now applied worldwide. Cryopreservation of pre- and postpubertal ovarian tissue containing primordial follicles, though still considered experimental, has already led to the birth of healthy babies after autotransplantation and is performed in an increasing number of centers. For prepubertal boys who do not produce gametes ready for fertilization, cryopreservation of immature testicular tissue (ITT) containing spermatogonial stem cells may be proposed as an experimental strategy with the aim of restoring fertility. Based on achievements in nonhuman primates, autotransplantation of ITT or testicular cell suspensions appears promising to restore fertility of young cancer survivors. So far, whether in two- or three-dimensional culture systems, in vitro maturation of immature male and female gonadal cells or tissue has not demonstrated a capacity to produce safe gametes for ART. Recently, primordial germ cells have been generated from embryonic and induced pluripotent stem cells, but further investigations regarding efficiency and safety are needed. Transplantation of mesenchymal stem cells to improve the vascularization of gonadal tissue grafts, increase the colonization of transplanted cells, and restore the damaged somatic compartment could overcome the current limitations encountered with transplantation.

Establishing reproductive potential and advances in fertility preservation techniques for XY individuals with differences in sex development

BACKGROUND

Discordance between gonadal type and gender identity has often led to an assumption of infertility in patients with differences in sex development (DSD). However, there is now greater recognition of fertility being an important issue for this group of patients. Currently, gonadal tissue that may have fertility potential is not being stored for individuals with DSD and, where gonadectomy forms part of management, is often discarded. The area of fertility preservation has been predominantly driven by oncofertility which is a field dedicated to preserving the fertility of patients undergoing gonadotoxic cancer treatment. The use of fertility preservation techniques could be expanded to include individuals with DSD where functioning gonads are present.

METHODS

This is a systematic literature review evaluating original research articles and relevant reviews between 1974 and 2018 addressing DSD and fertility, in vitro maturation of sperm, and histological/ultrastructural assessment of gonadal tissue in complete and partial androgen insensitivity syndrome, 17β-hydroxysteroid dehydrogenase type 3 and 5α-reductase deficiency.

CONCLUSION

Successful clinical outcomes of ovarian tissue cryopreservation are paving the way for similar research being conducted using testicular tissue and sperm. There have been promising results from both animal and human studies leading to cryopreservation of testicular tissue now being offered to boys prior to cancer treatment. Although data are limited, there is evidence to suggest the presence of reproductive potential in the gonads of some individuals with DSD. Larger, more detailed studies are required, but if these continue to be encouraging, individuals with DSD should be given the same information, opportunities and access to fertility preservation as other patient groups.

Identification of Premeiotic, Meiotic, and Postmeiotic Cells in Testicular Biopsies Without Sperm from Sertoli Cell-Only Syndrome Patients

Sertoli cell-only syndrome (SCOS) affects about 26.3⁻57.8% of azoospermic men, with their seminiferous tubules containing only Sertoli cells. Recently, it was reported that testicular biopsies from nonobstructive azoospermic (NOA) patients contained germ cells, and that sperm could be found in the tubules of 20% of SCOS patients using testicular sperm extraction technology. Since the patients without sperm in their testicular biopsies do not have therapy to help them to father a biological child, in vitro maturation of spermatogonial stem cells (SSCs) isolated from their testis is a new approach for possible future infertility treatment. Recently, the induction of human and mice SSCs proliferation and differentiation was demonstrated using different culture systems. Our group reported the induction of spermatogonial cell proliferation and differentiation to meiotic and postmeiotic stages in mice, rhesus monkeys, and prepubertal boys with cancer using 3D agar and methylcellulose (MCS) culture systems. The aim of the study was to identify the type of spermatogenic cells present in biopsies without sperm from SCOS patients, and to examine the possibility of inducing spermatogenesis from isolated spermatogonial cells of these biopsies in vitro using 3D MCS. We used nine biopsies without sperm from SCOS patients, and the presence of spermatogenic markers was evaluated by PCR and specific immunofluorescence staining analyses. Isolated testicular cells were cultured in MCS in the presence of StemPro enriched media with different growth factors and the development of colonies/clusters was examined microscopically. We examined the presence of cells from the different stages of spermatogenesis before and after culture in MCS for 3⁻7 weeks. Our results indicated that these biopsies showed the presence of premeiotic markers (two to seven markers/biopsy), meiotic markers (of nine biopsies, cAMP responsive element modulator-1 (CREM-1) was detected in five, lactate dehydrogenase (LDH) in five, and BOULE in three) and postmeiotic markers (protamine was detected in six biopsies and acrosin in three). In addition, we were able to induce the development of meiotic and/or postmeiotic stages from spermatogonial cells isolated from three biopsies. Thus, our study shows for the first time the presence of meiotic and/or postmeiotic cells in biopsies without the sperm of SCOS patients. Isolated cells from some of these biopsies could be induced to meiotic and/or postmeiotic stages under in vitro culture conditions.

How does chemotherapy treatment damage the prepubertal testis?

Chemotherapy treatment is a mainstay of anticancer regimens, significantly contributing to the recent increase in childhood cancer survival rates. Conventional cancer therapy targets not only malignant but also healthy cells resulting in side effects including infertility. For prepubertal boys, there are currently no fertility preservation strategies in use, although several potential methods are under investigation. Most of the current knowledge in relation to prepubertal gonadotoxicity has been deduced from adult studies; however, the prepubertal testis is relatively quiescent in comparison to the adult. This review provides an overview of research to date in humans and animals describing chemotherapy-induced prepubertal gonadotoxicity, focusing on direct gonadal damage. Testicular damage is dependent upon the agent, dosage, administration schedule and age/pubertal status at time of treatment. The chemotherapy agents investigated so far target the germ cell population activating apoptotic pathways and may also impair Sertoli cell function. Due to use of combined chemotherapy agents for patients, the impact of individual drugs is hard to define, however, use of in vivo and in vitro animal models can overcome this problem. Furthering our understanding of how chemotherapy agents target the prepubertal testis will provide clarity to patients on the gonadotoxicity of different drugs and aid in the development of cytoprotective agents.

Development of Spermatogenesis In Vitro in Three-Dimensional Culture from Spermatogonial Cells of Busulfan-Treated Immature Mice

Aggressive chemotherapy may lead to permanent male infertility. Prepubertal males do not generate sperm, but their testes do contain spermatogonial cells (SPGCs) that could be used for fertility preservation. In the present study, we examined the effect of busulfan (BU) on the SPGCs of immature mice, and the possible induction of the survivor SPGCs to develop spermatogenesis in 3D in-vitro culture. Immature mice were injected with BU, and after 0.5⁻12 weeks, their testes were weighed and evaluated histologically compared to the control mice. The spermatogonial cells [Sal-like protein 4 (SALL4) and VASA (a member of the DEAD box protein family) in the testicular tissue were counted/seminiferous tubule (ST). The cells from the STs were enzymatically isolated and cultured in vitro. Our results showed a significant decrease in the testicular weight of the BU-treated mice compared to the control. This was in parallel to a significant increase in the number of severely damaged STs, and a decrease in the number of SALL4 and VASA/STs compared to the control. The cultures of the isolated cells from the STs of the BU-treated mice showed a development of colonies and meiotic and post-meiotic cells after four weeks of culture. The addition of homogenates from adult GFP mice to those cultures induced the development of sperm-like cells after four weeks of culture. This is the first study demonstrating the presence of biologically active spermatogonial cells in the testicular tissue of BU-treated immature mice, and their capacity to develop sperm-like cells in vitro.