Histological study on the influence of puberty suppression and hormonal treatment on developing germ cells in transgender women.

STUDY QUESTION: Can transgender women cryopreserve germ cells obtained from their orchiectomy specimen for fertility preservation, after having used puberty suppression and/or hormonal treatment? SUMMARY ANSWER: In the vast majority of transgender women, there were still immature germ cells present in the orchiectomy specimen, and in 4.7% of transgender women-who all initiated medical treatment in Tanner stage 4 or higher-mature spermatozoa were found, which would enable cryopreservation of spermatozoa or testicular tissue after having used puberty suppression and/or hormonal treatment. WHAT IS KNOWN ALREADY: Gender affirming treatment (i.e. puberty suppression, hormonal treatment, and subsequent orchiectomy) impairs reproductive function in transgender women. Although semen cryopreservation is generally offered during the transition process, this option is not feasible for all transgender women (e.g. due to incomplete spermatogenesis when initiating treatment in early puberty, in case of inability to masturbate, or when temporary cessation of hormonal treatment is too disruptive). Harvesting mature spermatozoa, or testicular tissue harboring immature germ cells, from orchiectomy specimens obtained during genital gender-affirming surgery (gGAS) might give this group a chance of having biological children later in life. Previous studies on spermatogenesis in orchiectomy specimens showed conflicting results, ranging from complete absence of germ cells to full spermatogenesis, and did not involve transgender women who initiated medical treatment in early- or late puberty. STUDY DESIGN, SIZE, DURATION: Histological and immunohistochemical analyses were performed on orchiectomy specimens from 214 transgender women who underwent gGAS between 2006 and 2018. Six subgroups were identified, depending on pubertal stage at initiation of medical treatment (Tanner stage 2-3, Tanner stage 4-5, adult), and whether hormonal treatment was continued or temporarily stopped prior to gGAS in each of these groups. PARTICIPANTS/MATERIALS, SETTING, METHODS: All transgender women used a combination of estrogens and testosterone suppressing therapy. Orchiectomy specimen sections were stained with Mayer's hematoxylin and eosin and histologically analyzed to assess the Johnsen score and the ratio of most advanced germ cell types in at least 50 seminiferous tubular cross-sections. Subsequently, immunohistochemistry was used to validate these findings using spermatogonia, spermatocytes or spermatids markers (MAGE-A3/A4, γH2AX, Acrosin, respectively). Possibilities for fertility preservation were defined as: preservation of spermatozoa, preservation of spermatogonial stem cells or no possibilities (in case no germ cells were found). Outcomes were compared between subgroups and logistic regression analyses were used to assess the association between the duration of hormonal treatment and the possibilities for fertility preservation. MAIN RESULTS AND THE ROLE OF CHANCE: Mature spermatozoa were encountered in 4.7% of orchiectomy specimens, all from transgender women who had initiated medical treatment in Tanner stage 4 or higher. In 88.3% of the study sample orchiectomy specimens only contained immature germ cells (round spermatids, spermatocytes or spermatogonia, as most advanced germ cell type). In 7.0%, a complete absence of germ cells was observed, all these samples were from transgender women who had initiated medical treatment in adulthood. Cessation of hormonal treatment prior to gGAS did not affect the presence of germ cells or their maturation stage, nor was there an effect of the duration of hormonal treatment prior to gGAS. LIMITATIONS, REASONS FOR CAUTION: Since data on serum hormone levels on the day of gGAS were not available, we were unable to verify if the transgender women who were asked to temporarily stop hormonal treatment 4 weeks prior to surgery actually did so, and if people with full spermatogenesis were compliant to treatment. WIDER IMPLICATIONS OF THE FINDINGS: There may still be options for fertility preservation in orchiectomy specimens obtained during gGAS since a small percentage of transgender women had full spermatogenesis, which could enable cryopreservation of mature spermatozoa via a testicular sperm extraction procedure. Furthermore, the vast majority still had immature germ cells, which could enable cryopreservation of testicular tissue harboring spermatogonial stem cells. If maturation techniques like in vitro spermatogenesis become available in the future, harvesting germ cells from orchiectomy specimens might be a promising option for those who are otherwise unable to have biological children. STUDY FUNDING/COMPETING INTEREST: None. TRIAL REGISTRATION NUMBER: N/A.

Bi-allelic variants in DNA mismatch repair proteins MutS Homolog MSH4 and MSH5 cause infertility in both sexes.

STUDY QUESTION: Do bi-allelic variants in the genes encoding the MSH4/MSH5 heterodimer cause male infertility? SUMMARY ANSWER: We detected biallelic, (likely) pathogenic variants in MSH5 (4 men) and MSH4 (3 men) in six azoospermic men, demonstrating that genetic variants in these genes are a relevant cause of male infertility. WHAT IS KNOWN ALREADY: MSH4 and MSH5 form a heterodimer, which is required for prophase of meiosis I. One variant in MSH5 and two variants in MSH4 have been described as causal for premature ovarian insufficiency (POI) in a total of five women, resulting in infertility. Recently, pathogenic variants in MSH4 have been reported in infertile men. So far, no pathogenic variants in MSH5 had been described in males. STUDY DESIGN, SIZE, DURATION: We utilized exome data from 1305 men included in the Male Reproductive Genomics (MERGE) study, including 90 males with meiotic arrest (MeiA). Independently, exome sequencing was performed in a man with MeiA from a large consanguineous family. PARTICIPANTS/MATERIALS, SETTING, METHODS: Assuming an autosomal-recessive mode of inheritance, we screened the exome data for rare, biallelic coding variants in MSH4 and MSH5. If possible, segregation analysis in the patients' families was performed. The functional consequences of identified loss-of-function (LoF) variants in MSH5 were studied using heterologous expression of the MSH5 protein in HEK293T cells. The point of arrest during meiosis was determined by γH2AX staining. MAIN RESULTS AND THE ROLE OF CHANCE: We report for the first time (likely) pathogenic, homozygous variants in MSH5 causing infertility in 2 out of 90 men with MeiA and overall in 4 out of 902 azoospermic men. Additionally, we detected biallelic variants in MSH4 in two men with MeiA and in the sister of one proband with POI. γH2AX staining revealed an arrest in early prophase of meiosis I in individuals with pathogenic MSH4 or MSH5 variants. Heterologous in vitro expression of the detected LoF variants in MSH5 showed that the variant p.(Ala620GlnTer9) resulted in MSH5 protein truncation and the variant p.(Ser26GlnfsTer42) resulted in a complete loss of MSH5. LARGE SCALE DATA: All variants have been submitted to ClinVar (SCV001468891-SCV001468896 and SCV001591030) and can also be accessed in the Male Fertility Gene Atlas (MFGA). LIMITATIONS, REASONS FOR CAUTION: By selecting for variants in MSH4 and MSH5, we were able to determine the cause of infertility in six men and one woman, leaving most of the examined individuals without a causal diagnosis. WIDER IMPLICATIONS OF THE FINDINGS: Our findings have diagnostic value by increasing the number of genes associated with non-obstructive azoospermia with high clinical validity. The analysis of such genes has prognostic consequences for assessing whether men with azoospermia would benefit from a testicular biopsy. We also provide further evidence that MeiA in men and POI in women share the same genetic causes. STUDY FUNDING/COMPETING INTEREST(S): This study was carried out within the frame of the German Research Foundation sponsored Clinical Research Unit 'Male Germ Cells: from Genes to Function' (DFG, CRU326), and supported by institutional funding of the Research Institute Amsterdam Reproduction and Development and funds from the LucaBella Foundation. The authors declare no conflict of interest.

The initial maturation status of marmoset testicular tissues has an impact on germ cell maintenance and somatic cell response in tissue fragment culture.

Successful in vitro spermatogenesis was reported using immature mouse testicular tissues in a fragment culture approach, raising hopes that this method could also be applied for fertility preservation in humans. Although maintaining immature human testicular tissue fragments in culture is feasible for an extended period, it remains unknown whether germ cell survival and the somatic cell response depend on the differentiation status of tissue. Employing the marmoset monkey (Callithrix jacchus), we aimed to assess whether the maturation status of prepubertal and peri-/pubertal testicular tissues influence the outcome of testis fragment culture. Testicular tissue fragments from 4- and 8-month-old (n = 3, each) marmosets were cultured and evaluated after 0, 7, 14, 28 and 42 days. Immunohistochemistry was performed for identification and quantification of germ cells (melanoma-associated antigen 4) and Sertoli cell maturation status (anti-Müllerian hormone: AMH). During testis fragment culture, spermatogonial numbers were significantly reduced (P < 0.05) in the 4- but not 8-month-old monkeys, at Day 0 versus Day 42 of culture. Moreover, while Sertoli cells from 4-month-old monkeys maintained an immature phenotype (i.e. AMH expression) during culture, AMH expression was regained in two of the 8-month-old monkeys. Interestingly, progression of differentiation to later meiotic stage was solely observed in one 8-month-old marmoset, which was at an intermediate state regarding germ cell content, with gonocytes as well as spermatocytes present, as well as Sertoli cell maturation status. Although species-specific differences might influence the outcome of testis fragment experiments in vitro, our study demonstrated that the developmental status of the testicular tissues needs to be considered as it seems to be decisive for germ cell maintenance, somatic cell response and possibly the differentiation potential.

Assessment of fresh and cryopreserved testicular tissues from (pre)pubertal boys during organ culture as a strategy for in vitro spermatogenesis.

STUDY QUESTION: Can the organ culture method be applied to both fresh and cryopreserved human (pre)pubertal testicular tissue as a strategy for in vitro spermatogenesis? SUMMARY ANSWER: Although induction of spermatogenesis was not achieved in vitro, testicular architecture, endocrine function and spermatogonial proliferation were maintained in both fresh and cryopreserved testicular tissues. WHAT IS KNOWN ALREADY: Cryopreservation of a testicular biopsy is increasingly offered as a fertility preservation strategy for prepubertal cancer patients. One of the proposed experimental approaches to restore fertility is the organ culture method, which, in the mouse model, successfully allows for in vitro development of spermatozoa from testicular biopsies. However, complete spermatogenesis from human prepubertal testicular tissue in such an organ culture system has not been demonstrated. STUDY DESIGN, SIZE, DURATION: Testicular tissue was collected from nine (pre)pubertal boys diagnosed with cancer (ranging from 6 to 14 years of age) admitted for fertility preservation before treatment. Testicular biopsies were either immediately processed for culture or first cryopreserved, using a controlled slow freezing protocol, and thawed before culture. Organ culture of testicular fragments was performed in two different media for a maximum period of 5 weeks, targeting early cellular events (viability, meiosis and somatic differentiation) in vitro. PARTICIPANTS/MATERIALS, SETTING, METHODS: Fresh and cryopreserved-thawed testis fragments (1-2 mm3) were cultured at a gas-liquid interphase (34°C, 5% CO2) in Minimum Essential Medium alpha + 10% knock-out serum replacement medium containing 10-7 M melatonin and 10-6 M retinoic acid, with or without 3 IU/L FSH/LH supplementation. The effect of culture conditions on testicular fragments was weekly assessed by histological evaluation of germ cell development and immunohistochemical identification of spermatogonia (using MAGEA4), proliferative status of spermatogonia and Sertoli cells (using proliferating cell nuclear antigen [PCNA]), intratubular cell apoptosis (by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) and Sertoli cells maturation (using Anti-Müllerian Hormone [AMH] versus Androgen Receptor [AR]). Additionally, Leydig cells' functionality was determined by measuring testosterone concentration in the culture media supernatants. MAIN RESULTS AND THE ROLE OF CHANCE: Neither fresh nor cryopreserved human (pre)pubertal testicular fragments were able to initiate spermatogenesis in our organ culture system. Nonetheless, our data suggest that fresh and cryopreserved testicular fragments have comparable functionality in the described organ culture conditions, as reflected by the absence of significant differences in any of the weekly evaluated functional parameters. Additionally, no significant differences were found between the two tested media when culturing fresh and cryopreserved human testicular fragments. Although spermatogonia survived and remained proliferative in all culture conditions, a significant reduction of the spermatogonial population (P ≤ 0.001) was observed over the culture period, justified by a combined reduction of proliferation activity (P ≤ 0.001) and increased intratubular cell apoptosis (P ≤ 0.001). We observed a transient increase in Sertoli cell proliferative activity, loss of AMH expression (P ≤ 0.001) but no induction of AR expression. Leydig cell endocrine function was successfully stimulated in vitro as indicated by increased testosterone production in all conditions throughout the entire culture period (P ≤ 0.02). LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Although not noticeable in this study, we cannot exclude that if an optimized culture method ensuring complete spermatogenesis in human testicular fragments is established, differences in functional or spermatogenic efficiency between fresh and cryopreserved tissue might be found. WIDER IMPLICATIONS OF THE FINDINGS: The current inability to initiate spermatogenesis in vitro from cryopreserved human testicular fragments should be included in the counselling of patients who are offered testicular tissue cryopreservation to preserve fertility. STUDY FUNDING/COMPETING INTEREST(S): This project was funded by EU-FP7-PEOPLE-2013-ITN 603568 `Growsperm'. None of the authors have competing interests. TRIAL REGISTRATION NUMBER: Not applicable.

Primary human testicular PDGFRα+ cells are multipotent and can be differentiated into cells with Leydig cell characteristics in vitro.

STUDY QUESTION: Is it possible to differentiate primary human testicular platelet-derived growth factor receptor alpha positive (PDGFRα+) cells into functional Leydig cells? SUMMARY ANSWER: Although human testicular PDGFRα+ cells are multipotent and are capable of differentiating into steroidogenic cells with Leydig cell characteristics, they are not able to produce testosterone after differentiation. WHAT IS KNOWN ALREADY: In rodents, stem Leydig cells (SLCs) that have been identified and isolated using the marker PDGFRα can give rise to adult testosterone-producing Leydig cells after appropriate differentiation in vitro. Although PDGFRα+ cells have also been identified in human testicular tissue, so far there is no evidence that these cells are true human SLCs that can differentiate into functional Leydig cells in vitro or in vivo. STUDY DESIGN, SIZE, DURATION: We isolated testicular cells enriched for interstitial cells from frozen-thawed fragments of testicular tissue from four human donors. Depending on the obtained cell number, PDGFRα+-sorted cells of three to four donors were exposed to differentiation conditions in vitro to stimulate development into adipocytes, osteocytes, chondrocytes or into Leydig cells. We compared their cell characteristics with cells directly after sorting and cells in propagation conditions. To investigate their differentiation potential in vivo, PDGFRα+-sorted cells were transplanted in the testis of 12 luteinizing hormone receptor-knockout (LuRKO) mice of which 6 mice received immunosuppression treatment. An additional six mice did not receive cell transplantation and were used as a control. PARTICIPANTS/MATERIALS, SETTING, METHODS: Human testicular interstitial cells were cultured to Passage 3 and FACS sorted for HLA-A,B,C+/CD34-/PDGFRα+. We examined their mesenchymal stromal cell (MSC) membrane protein expression by FACS analyses. Furthermore, we investigated lineage-specific staining and gene expression after MSC trilineage differentiation. For the differentiation into Leydig cells, PDGFRα+-sorted cells were cultured in either proliferation or differentiation medium for 28 days, after which they were stimulated either with or without hCG, forskolin or dbcAMP for 24 h to examine the increase in gene expression of steroidogenic enzymes using qPCR. In addition, testosterone, androstenedione and progesterone levels were measured in the culture medium. We also transplanted human PDGFRα+-sorted testicular interstitial cells into the testis of LuRKO mice. Serum was collected at several time points after transplantation, and testosterone was measured. Twenty weeks after transplantation testes were collected for histological examination. MAIN RESULTS AND THE ROLE OF CHANCE: From primary cultured human testicular interstitial cells at Passage 3, we could obtain a population of HLA-A,B,C+/CD34-/PDGFRα+ cells by FACS. The sorted cells showed characteristics of MSC and were able to differentiate into adipocytes, chondrocytes and osteocytes. Upon directed differentiation into Leydig cells in vitro, we observed a significant increase in the expression of HSD3B2 and INSL3. After 24 h stimulation with forskolin or dbcAMP, a significantly increased expression of STAR and CYP11A1 was observed. The cells already expressed HSD17B3 and CYP17A1 before differentiation but the expression of these genes were not significantly increased after differentiation and stimulation. Testosterone levels could not be detected in the medium in any of the stimulation conditions, but after stimulation with forskolin or dbcAMP, androstenedione and progesterone were detected in culture medium. After transplantation of the human cells into the testes of LuRKO mice, no significant increase in serum testosterone levels was found compared to the controls. Also, no human cells were identified in the interstitium of mice testes 20 weeks after transplantation. LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: This study was performed using tissue from only four donors because of limitations in donor material. Because of the need of sufficient cell numbers, we first propagated cells to passage 3 before FACS of the desired cell population was performed. We cannot rule out this propagation of the cells resulted in loss of stem cell properties. WIDER IMPLICATIONS OF THE FINDINGS: A lot of information on Leydig cell development is obtained from rodent studies, while the knowledge on human Leydig cell development is very limited. Our study shows that human testicular interstitial PDGFRα+ cells have different characteristics compared to rodent testicular PDGFRα+ cells in gene expression levels of steroidogenic enzymes and potential to differentiate in adult Leydig cells under comparable culture conditions. This emphasizes the need for confirming results from rodent studies in the human situation to be able to translate this knowledge to the human conditions, to eventually contribute to improvements of testosterone replacement therapies or establishing alternative cell therapies in the future, potentially based on SLCs. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by Amsterdam UMC, location AMC, Amsterdam, the Netherlands. All authors declare no competing interests.

Simultaneous Purification of Round and Elongated Spermatids from Testis Tissue Using a FACS-Based DNA Ploidy Assay.

Spermiogenesis is the final phase of spermatogenesis during which post-meiotic haploid round spermatids (rSpt) differentiate into elongated spermatozoa and includes several critical cell-specific processes like DNA condensation, formation of the acrosome, and production of the flagellum. Disturbances in this process will lead to complications in sperm development and subsequently cause infertility. As such, studying spermiogenesis has clinical relevance in investigating the etiology of male infertility and will improve our scientific understanding of male germ cell formation. Here, we were able to purify round spermatid and elongated spermatid fractions from a single cryopreserved human testicular tissues sample with an efficiency of 85.4% ± 4.9% and 97.6% ± 0.6%, respectively. We confirmed the cell types by morphology and immunohistochemistry for histone H4 and PNA protein expression. The purity was measured by manual counting of histone H4 positive (round) and negative (elongated) spermatids in both sorted 1 N cell fractions. This method can be applied to both human and rodent studies. Especially in studies with limited access to testicular tissue, this method provides a reliable means to simultaneously isolate these cell types with high purity. Our method allows for further investigation of germ cell development and the process of spermiogenesis in particular, as well as provides a tool to study the etiology of male infertility, including morphological and biochemical assessment of round and elongating spermatids from subfertile men. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

Development of the testis in pre-pubertal boys with cancer after biopsy for fertility preservation.

STUDY QUESTION: Is testicular growth affected by a testicular biopsy intended for fertility preservation in pre-pubertal boys with cancer? SUMMARY ANSWER: Testicular growth of the biopsied testis is not impeded in comparison to the non-biopsied contralateral testis up until 1 year after surgery. WHAT IS KNOWN ALREADY: Fertility preservation in pre-pubertal boys by means of testicular biopsy has been conducted for more than 15 years. Although immediate adverse effects of testicular biopsy are rare (1%), no data exist on the effect of biopsy on testicular growth. STUDY DESIGN, SIZE, DURATION: In this prospective cohort study, between March 2011 and February 2017, 93 parents of pre-pubertal boys were offered cryopreservation of testicular tissue of their son, of whom 78 consented. Sixty-four boys were included in this follow-up study. PARTICIPANTS/MATERIALS, SETTING, METHODS: All boys with cancer at the paediatric oncology department of the Academic Medical Center (AMC) who needed gonadotoxic therapy and were unable to ejaculate were offered cryopreservation of testicular tissue prior to treatment. By testicular ultrasound before and after biopsy (1, 6 and 12 months after biopsy), volume and parenchymal abnormalities were assessed. Data were analysed using mixed-effects modelling. MAIN RESULTS AND THE ROLE OF CHANCE: Of the 64 included boys all were followed up at 1 month, 58 at 6 months and 55 at 12 months. Mean testicular volumes after 1, 6 and 12 months after biopsy were 1.7 ± 2.1, 1.7 ± 2.2 and 1.9 ± 2.4 for the biopsied testis and 1.8 ± 2.2, 1.8 ± 2.3 and 2.0 ± 2.2 for the non-biopsied testis, respectively. Biopsy of the testis did not have a significant impact on testicular growth. Immediate adverse effects of the biopsy, i.e. wound infections, were seen in 3/78 boys (3.8%). LIMITATIONS, REASONS FOR CAUTION: Although it is the largest cohort available to date, the number of patients included in our follow-up is still relatively small. A larger cohort would be able to evaluate growth more precisely. Follow-up was discontinued in a significant portion of boys, 12/76 (15.8%), mainly because of death due to primary illness but also because they could not be reached or declined further follow-up. WIDER IMPLICATIONS OF THE FINDINGS: These reassuring data may be used in counselling future boys who are eligible for fertility preservation and their parents. STUDY FUNDING/COMPETING INTEREST(S): Study funded by KIKA Foundation (Kika 86), Grant from the Netherlands Organisation for Health Research and Development (ZonMW TAS-116003002). The authors declare no conflict of interest. TRIAL REGISTRATION NUMBER: CCMO-register: NL27690.000.09.

Stem cells in reproductive medicine: ready for the patient?

STUDY QUESTION: Are there effective and clinically validated stem cell-based therapies for reproductive diseases? SUMMARY ANSWER: At the moment, clinically validated stem cell treatments for reproductive diseases and alterations are not available. WHAT IS KNOWN ALREADY: Research in stem cells and regenerative medicine is growing in scope, and its translation to the clinic is heralded by the recent initiation of controlled clinical trials with pluripotent derived cells. Unfortunately, stem cell 'treatments' are currently offered to patients outside of the controlled framework of scientifically sound research and regulated clinical trials. Both physicians and patients in reproductive medicine are often unsure about stem cells therapeutic options. STUDY DESIGN, SIZE, DURATION: An international working group was assembled to review critically the available scientific literature in both the human species and animal models. PARTICIPANTS/MATERIALS, SETTING, METHODS: This review includes work published in English until December 2014, and available through Pubmed. MAIN RESULTS AND THE ROLE OF CHANCE: A few areas of research in stem cell and reproductive medicine were identified: in vitro gamete production, endometrial regeneration, erectile dysfunction amelioration, vaginal reconstruction. The stem cells studied range from pluripotent (embryonic stem cells and induced pluripotent stem cells) to monopotent stem cells, such as spermatogonial stem cells or mesenchymal stem cells. The vast majority of studies have been carried out in animal models, with data that are preliminary at best. LIMITATIONS, REASONS FOR CAUTION: This review was not conducted in a systematic fashion, and reports in publications not indexed in Pubmed were not analyzed. WIDER IMPLICATIONS OF THE FINDINGS: A much broader clinical knowledge will have to be acquired before translation to the clinic of stem cell therapies in reproductive medicine; patients and physicians should be wary of unfounded claims of improvement of existing medical conditions; at the moment, effective stem cell treatment for reproductive diseases and alterations is not available. STUDY FUNDING/COMPETING INTERESTS: None. TRIAL REGISTRATION NUMBER: NA.

AZFc deletions do not affect the function of human spermatogonia in vitro.

Azoospermic factor c (AZFc) deletions are the underlying cause in 10% of azoo- or severe oligozoospermia. Through extensive molecular analysis the precise genetic content of the AZFc region and the origin of its deletion have been determined. However, little is known about the effect of AZFc deletions on the functionality of germ cells at various developmental steps. The presence of normal, fertilization-competent sperm in the ejaculate and/or testis of the majority of men with AZFc deletions suggests that the process of differentiation from spermatogonial stem cells (SSCs) to mature spermatozoa can take place in the absence of the AZFc region. To determine the functionality of AZFc-deleted spermatogonia, we compared in vitro propagated spermatogonia from six men with complete AZFc deletions with spermatogonia from three normozoospermic controls. We found that spermatogonia of AZFc-deleted men behave similar to controls during culture. Short-term (18 days) and long-term (48 days) culture of AZFc-deleted spermatogonia showed the same characteristics as non-deleted spermatogonia. This similarity was revealed by the same number of passages, the same germ cell clusters formation and similar level of genes expression of spermatogonial markers including ubiquitin carboxyl-terminal esterase L1 (UCHL1), zinc finger and BTB domain containing 16 (ZBTB16) and glial cell line-derived neurotrophic factor family receptor alpha 1 (GFRA1), as well as germ cell differentiation markers including signal transducer and activator of transcription 3 (STAT3), spermatogenesis and oogenesis specific basic helix-loophelix 2 (SOHLH2), v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT) and synaptonemal complex protein 3 (SYCP3). The only exception was melanoma antigen family A4 (MAGEA4) which showed significantly lower expression in AZFc-deleted samples than controls in short-term culture while in long-term culture it was hardly detected in both AZFc-deleted and control spermatogonia. These data suggest that, at least in vitro, spermatogonia of AZFc-deleted men are functionally similar to spermatogonia from non-deleted men. Potentially, this enables treatment of men with AZFc deletions by propagating their SSCs in vitro and autotransplanting these SSCs back to the testes to increase sperm counts and restore fertility.

Transgenic overexpression of regucalcin leads to suppression of thapsigargin- and actinomycin D-induced apoptosis in the testis by modulation of apoptotic pathways.

Recent evidence suggested the involvement of calcium-binding protein regucalcin (RGN) in testicular apoptosis. Herein, we investigated the role of RGN controlling apoptotic pathways in the testis by using a transgenic rat model overexpressing RGN (Tg-RGN). Seminiferous tubules (SeT) from Tg-RGN and their wild-type (Wt) counterparts were cultured ex vivo in presence or absence of apoptosis inducers thapsigargin (Thap, 10(-7) and 10(-6) m) and actinomycin D (Act D, 0.5 and 1 µg/mL). Expression levels of key regulators of apoptosis in SeT of Tg-RGN and Wt animals were determined by quantitative real-time PCR and Western blot analysis. Measurement of caspase-3 enzymatic activity was included as an end point of apoptosis. Tg-RGN SeT treated with 10(-6) m of Thap or 1 µg/mL of Act D showed a diminished enzymatic activity and gene transcription of caspase-3, along with increased mRNA and protein expression of antiapoptotic Bcl-2. Bcl-2/Bax (antiapoptotic/proapoptotic) protein ratio was also enhanced in these SeT. Although caspase-9 mRNA was increased in the SeT of Tg-RGN treated with Thap, no differences were observed at protein level, and no differences were also found on protein levels of apoptosis-inducing factor. mRNA expression of proapoptotic p53 and p21 was strongly decreased in Tg-RGN SeT treated with Thap (10(-6) m) or Act D (1 µg/mL). These findings demonstrated that RGN suppresses Thap- and Act D-induced apoptosis in SeT by modulating the expression and activity of key apoptotic and antiapoptotic factors. Moreover, results indicate that RGN overexpression protects germ cell from apoptosis induced by noxious stimuli, which could be a relevant mechanism for fertility preservation in situations of oncological treatments.

Mesenchymal origin of multipotent human testis-derived stem cells in human testicular cell cultures.

In contrast to mouse germ cell-derived pluripotent stem cells, the pluripotent state of human testis-derived embryonic stem cell (ESC)-like that spontaneously arise in primary testicular cell cultures remains controversial. Recent studies have shown that these cells closely resemble multipotent mesenchymal stem cells (MSCs), raising the question of their origin and designating these cell populations as multipotent human testis-derived stem cells (mhtSCs) rather than truly ESC-like cells. Here, we evaluate the origin of mhtSCs in vitro by culturing selected testicular cell types. We demonstrate that mhtSCs can be obtained equally efficiently in cultures of pure testicular somatic cells devoid of germ cells. Conversely, cultures with a purified population of germ cells/spermatogonia do not produce any mhtSCs. Based on common molecular characteristics of the somatic starting population and mhtSCs, we conclude that mhtSCs colonies originate from somatic mesenchymal progenitors present in primary testicular cell cultures and do not arise from germ cells undergoing incomplete reprogramming in vitro.

Role for rodent Smc6 in pericentromeric heterochromatin domains during spermatogonial differentiation and meiosis.

Chromatin structure and function are for a large part determined by the six members of the structural maintenance of chromosomes (SMC) protein family, which form three heterodimeric complexes: Smc1/3 (cohesin), Smc2/4 (condensin) and Smc5/6. Each complex has distinct and important roles in chromatin dynamics, gene expression and differentiation. In yeast and Drosophila, Smc6 is involved in recombinational repair, restarting collapsed replication forks and prevention of recombination in repetitive sequences such as rDNA and pericentromeric heterochromatin. Although such DNA damage control mechanisms, as well as highly dynamic changes in chromatin composition and function, are essential for gametogenesis, knowledge on Smc6 function in mammalian systems is limited. We therefore have investigated the role of Smc6 during mammalian spermatogonial differentiation, meiosis and subsequent spermiogenesis. We found that, during mouse spermatogenesis, Smc6 functions as part of meiotic pericentromeric heterochromatin domains that are initiated when differentiating spermatogonia become irreversibly committed toward meiosis. To our knowledge, we are the first to provide insight into how commitment toward meiosis alters chromatin structure and dynamics, thereby setting apart differentiating spermatogonia from the undifferentiated spermatogonia, including the spermatogonial stem cells. Interestingly, Smc6 is not essential for spermatogonial mitosis, whereas Smc6-negative meiotic cells appear unable to finish their first meiotic division. Importantly, during meiosis, we find that DNA repair or recombination sites, marked by γH2AX or Rad51 respectively, do not co-localize with the pericentromeric heterochromatin domains where Smc6 is located. Considering the repetitive nature of these domains and that Smc6 has been previously shown to prevent recombination in repetitive sequences, we hypothesize that Smc6 has a role in the prevention of aberrant recombination events between pericentromeric regions during the first meiotic prophase that would otherwise cause chromosomal aberrations leading to apoptosis, meiotic arrest or aneuploidies.

Human testis-derived embryonic stem cell-like cells are not pluripotent, but possess potential of mesenchymal progenitors.

BACKGROUND: Spontaneous in vitro transition of undifferentiated spermatogonia into the pluripotent cell state has been achieved using neonatal and adult mouse testis tissue. In an effort to establish an analogous source of human patient-specific pluripotent stem cells, several research groups have described the derivation of embryonic stem cell-like cells from primary cultures of human testis. These cells are characterized in all studies as growing in compact colonies, expressing pluripotency-associated markers and possessing multilineage differentiation capabilities in vitro, but only one study claimed their ability to induce teratomas. This controversy initiated a debate about the pluripotent state and origin of human testis-derived ES-like cells (htES-like cells). METHODS: htES-like cell colonies were obtained from primary testicular cultures of three individuals and selectively expanded using culture conditions known to support the propagation of blastocyst-derived human embryonic stem cells (ESCs), mouse epiblast stem cells and 'naïve' human ESCs. The stem cell properties of htES-like cells were subsequently assessed by testing the expression of ESC-specific markers, differentiation abilities in vitro and in vivo, and microarray profiling. RESULTS: The expression of pluripotency-associated markers in htES-like cells and their differentiation abilities differed significantly from those of ESCs. Gene expression microarray analysis revealed that htES-like cells possess a transcriptome distinct from human ESCs and fibroblasts, but closely resembling the transcriptome of mesenchymal stem cells (MSCs). The similarity to MSCs was confirmed by detection of SSEA4/CD146 expressing cells within htES-like colonies and efficient in vitro differentiation toward three mesodermal lineages (adipogenic, osteogenic, chondrogenic). CONCLUSIONS: Taken together, these results indicate that htES-like cells, in contrast to pluripotent stem cells derived from adult mouse testis, are not pluripotent and most likely not of germ cell but of mesenchymal origin.

Embryonic stem cell-like cells derived from adult human testis.

BACKGROUND: Given the significant drawbacks of using human embryonic stem (hES) cells for regenerative medicine, the search for alternative sources of multipotent cells is ongoing. Studies in mice have shown that multipotent ES-like cells can be derived from neonatal and adult testis. Here we report the derivation of ES-like cells from adult human testis. METHODS: Testis material was donated for research by four men undergoing bilateral castration as part of prostate cancer treatment. Testicular cells were cultured using StemPro medium. Colonies that appeared sharp edged and compact were collected and subcultured under hES-specific conditions. Molecular characterization of these colonies was performed using RT-PCR and immunohistochemistry. (Epi)genetic stability was tested using bisulphite sequencing and karyotype analysis. Directed differentiation protocols in vitro were performed to investigate the potency of these cells and the cells were injected into immunocompromised mice to investigate their tumorigenicity. RESULTS: In testicular cell cultures from all four men, sharp-edged and compact colonies appeared between 3 and 8 weeks. Subcultured cells from these colonies showed alkaline phosphatase activity and expressed hES cell-specific genes (Pou5f1, Sox2, Cripto1, Dnmt3b), proteins and carbohydrate antigens (POU5F1, NANOG, SOX2 and TRA-1-60, TRA-1-81, SSEA4). These ES-like cells were able to differentiate in vitro into derivatives of all three germ layers including neural, epithelial, osteogenic, myogenic, adipocyte and pancreatic lineages. The pancreatic beta cells were able to produce insulin in response to glucose and osteogenic-differentiated cells showed deposition of phosphate and calcium, demonstrating their functional capacity. Although we observed small areas with differentiated cell types of human origin, we never observed extensive teratomas upon injection of testis-derived ES-like cells into immunocompromised mice. CONCLUSIONS: Multipotent cells can be established from adult human testis. Their easy accessibility and ethical acceptability as well as their non-tumorigenic and autogenic nature make these cells an attractive alternative to human ES cells for future stem cell therapies.

Mutations in the testis-specific NALP14 gene in men suffering from spermatogenic failure.

BACKGROUND: Because of the common use of ICSI and the potential genetic aetiology of spermatogenic failure, concern has been raised about transmitting genetic disorders to ICSI offspring. However, to date, in only approximately 15% of all cases of spermatogenic failure, an underlying genetic cause can be identified. We have previously established an association between spermatogenic failure and chromosomal region 11p15. In this study, we set out to explore whether NALP14, a gene recently mapped to 11p15, has a function in spermatogenesis and whether mutations in NALP14 can cause spermatogenic failure. METHODS: We applied two different multiple tissue northern (MTN) blots to determine tissue specificity of NALP14 and performed immunohistochemistry on human testis with anti-NALP14 antiserum. To determine imprinting status of NALP14, we tested the expression pattern of two single-nucleotide polymorphisms (SNPs) in human testis. Finally, we performed a mutation screen of the NALP14 gene in 157 men with azoospermia or severe oligozoospermia by direct sequencing; 158 normospermic men served as controls. RESULTS: NALP14 was, as are the three other genes in 11p15, exclusively expressed in testis. Within the testis, the NALP14 protein was mainly expressed in A dark spermatogonia, mid and late spermatocytes and spermatids. The mutation screen revealed five mutations that occurred only in the patient group. One of these unique mutations introduced an early stop codon in the NALP14 sequence, predicted to result in a severely truncated protein. CONCLUSION: Our data suggest that NALP14 has a function in spermatogenesis and that mutations in this gene might cause spermatogenic failure.

Expression of the scaffolding subunit A of protein phosphatase 2A during rat testicular development.

Previously, we found that the poly(A)+ RNA of the scaffolding subunit A (alpha isoform) of protein phosphatase 2A (PP2A-Aalpha) was clearly expressed by fetal gonocytes but weakly expressed by adult single (As), paired (Apr), and aligned (Aal) A spermatogonia. The scaffolding subunit A of PP2A (PP2A-A) is the major subunit in the formation of a functional PP2A holoenzyme. In this study, we investigated the expression of PP2A-A during testicular development in more detail using in situ hybridization, immunohistochemistry, and Western blot with testes of rats of various ages from 16 days postcoitum (pc) to adulthood. The expression of PP2A-A was detected in fetal proliferative gonocytes at 16 days pc, declining thereafter during the quiescent period of the gonocytes. From the day of birth to the start of spermatogenesis (Day 4 postpartum [pp]), the number of PP2A-A-immunopositive gonocytes increased. At Day 4 pp, the first A1 spermatogonia appeared along the basement membrane; all were PP2A-A positive. In the adult, PP2A-A was upregulated during the differentiation of the As, Apr, and Aal spermatogonia to the A1 spermatogonia and expressed thereafter by all other spermatogonia. Spermatocytes from the pachytene stage onward and all spermatids in the adult testis also showed clear expression of PP2A-A. In Sertoli cells, PP2A-A was detected during their proliferative period at 19 days pc to 15 days pp. The presence of a functional enzyme was confirmed by the additional detection of the catalytic subunit C of PP2A using Western blot analyses at various ages during testicular development. This apparent pattern of expression of PP2A-A during testicular development suggests that PP2A may play an important role in the proliferation of distinct populations of testicular cells and during meiosis and sperm maturation.

Transplantation of germ cells from glial cell line-derived neurotrophic factor-overexpressing mice to host testes depleted of endogenous spermatogenesis by fractionated irradiation.

With a novel method of eliminating spermatogenesis in host animals, male germ cells isolated from mice with targeted overexpression of glial cell line-derived neurotrophic factor (GDNF) were transplanted to evaluate their ability to reproduce the phenotype previously found in the transgenic animals. Successful depletion of endogenous spermatogenesis was achieved using fractionated ionizing irradiation. A dose of 1.5 Gy followed by a dose of 12 Gy after 24 h reduced the percentage of tubule cross-sections displaying endogenous spermatogenesis to approximately 3% and 10% as evidenced by histologic evaluation of testes at 12 and 21 wk, respectively, after irradiation. At this dose, no apparent harmful side effects were noted in the animals. Upon transplantation, GDNF-overexpressing germ cells were found to be able to repopulate the irradiated testes and to form clusters of spermatogonia-like cells resembling those found in the overexpressing donor mice. The cluster cells in transplanted host testes expressed human GDNF, as had been shown previously for clusters in donor animals, and both were strongly positive for the tyrosine kinase receptor Ret. Thus, we devised an efficient method for depleting the seminiferous epithelium of host mice without appreciable adverse effects. In these host mice, GDNF-overexpressing cells reproduced the aberrant phenotype found in the donor transgenic mice.

Maintenance of adult mouse type A spermatogonia in vitro: influence of serum and growth factors and comparison with prepubertal spermatogonial cell culture.

The culture of spermatogonial cells under well-defined conditions would be an important method for elucidating the mechanisms involved in spermatogenesis and in establishing tissue regeneration in vivo. In this study, a serum-free culture system was established, with type A spermatogonia isolated from adult vitamin A-deficient mice. At days 1, 3 and 7 of culture, the viability and proliferation of cells were monitored. The viability of the cells decreased by day 7 to 10% of the cells present. Proliferation occurred mainly during day 1, when 1% of the germ cells was proliferating. Co-labelling for a germ cell marker (heat shock protein-90alpha, Hsp90alpha), and a marker used to detect dividing cells (bromodeoxyuridine, BrdU), showed that this proliferation was restricted to germ cells. In an attempt to improve these parameters, medium containing fetal calf serum (FCS) was used. Viability was not influenced by serum, but proliferation was markedly enhanced. However, after day 7 of incubation with FCS, co-immunolocalization for Hsp90alpha and BrdU showed a preferential proliferation of somatic cells. Comparison of cultures of adult cells with cultures of prepubertal germ cells, commonly used in studies of spermatogenesis, showed that prepubertal germ cells are twice as viable. In addition, a different proliferation profile was observed, with a peak at day 3. Here, a distinct proliferation of somatic cells was also noted. The results from the present study indicate that the origin of isolated germ cells partly determines culture outcome and that cultures of prepubertal germ cells may not be representative for adult spermatogenesis. Moreover, adding FCS to the culture medium invokes the risk of profound and undesirable effects on cell composition, also underlining the need for identification of germ cells during culture.