Effect of childhood acute lymphoblastic leukemia therapy on spermatogonia populations and future fertility

Preservation of fertility in female and male prepubertal patients diagnosed with cancer

Over the past two decades, the importance of fertility preservation has grown not only in the realm of medical and clinical patient care, but also in the field of basic and applied research in human reproduction. With advancements in cancer treatments resulting in higher rates of patient survival, it is crucial to consider the quality of life post-cure. Therefore, fertility preservation must be taken into account prior to antitumor treatments, as it can significantly impact a patient's future fertility. For postpubertal patients, gamete cryopreservation is the most commonly employed preservation strategy. However, for prepubertal patients, the situation is more intricate. Presently, ovarian tissue cryopreservation is the standard practice for prepubertal girls, but further scientific evidence is required in several aspects. Testicular tissue cryopreservation, on the other hand, is still experimental for prepubertal boys. The primary aim of this review is to address the strategies available for possible fertility preservation in prepubertal girls and boys, such as ovarian cryopreservation/transplantation, in vitro follicle culture and meiotic maturation, artificial ovary, transplantation of cryopreserved spermatogonia, and cryopreservation/grafting of immature testicular tissue and testicular organoids.

Impact of low- or moderate-risk gonadotoxic chemotherapy prior to testicular tissue freezing on spermatogonia quantity in human (pre)pubertal testicular tissue

STUDY QUESTION

What is the impact of low- or moderate-risk gonadotoxic chemotherapy received prior to testicular tissue freezing (TTF), and of the cancer itself, on spermatogonia quantity in testicular tissue from (pre)pubertal boys?

SUMMARY ANSWER

Vincristine, when associated with alkylating agents, has an additional adverse effect on spermatogonia quantity, while carboplatin has no individual contribution to spermatogonia quantity, in testicular tissue of (pre)pubertal boys, when compared to patients who have received non-alkylating chemotherapy.

WHAT IS KNOWN ALREADY

The improved survival rates after cancer treatment necessitate the inclusion of fertility preservation procedures as part of the comprehensive care for patients, taking into consideration their age. Sperm cryopreservation is an established procedure in post-pubertal males while the TTF proposed for (pre)pubertal boys remains experimental. Several studies exploring testicular tissue of (pre)pubertal boys after TTF have examined the tubular fertility index (TFI, percentage of seminiferous tubule cross-sections containing spermatogonia) and the number of spermatogonia per seminiferous tubule cross-section (S/T). All studies have demonstrated that TFI and S/T always decrease after the introduction of chemotherapeutic agents, especially those which carry high gonadotoxic risks such as alkylating agents.

STUDY DESIGN, SIZE, DURATION

Testicular tissue samples from 79 (pre)pubertal boys diagnosed with cancer (from 6 months to 16 years of age) were cryopreserved between May 2009 and June 2014. Their medical diagnoses and previous chemotherapy exposures were recorded. We examined histological sections of (pre)pubertal testicular tissue to elucidate whether the chemotherapy or the primary diagnosis affects mainly TFI and S/T.

PARTICIPANTS/MATERIALS, SETTING, METHODS

(Pre)pubertal boys with cancer diagnosis who had been offered TTF prior to conditioning treatment for hematopoietic stem cell transplantation were included in the study. All the patients had previously received chemotherapy with low- or moderate-risk for future fertility. We have selected patients for whom the information on the chemotherapy received was complete. The quantity of spermatogonia and quality of testicular tissue were assessed by both morphological and immunohistochemical analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

A significant reduction in the number of spermatogonia was observed in boys treated with alkylating agents. The mean S/T values in boys exposed to alkylating agents were significantly lower compared to boys exposed to non-alkylating agents (P = 0.018). In contrast, no difference was observed for patients treated with carboplatin as the sole administered alkylating agent compared to the group of patients exposed to non-alkylating agents. We observed an increase of S/T with age in the group of patients who did not receive any alkylating agent and a decrease of S/T with age when patients received alkylating agents included in the cyclophosphamide equivalent dose (CED) formula (r = 0.6166, P = 0.0434; r = -0.3759, P = 0.0036, respectively). The TFI and S/T decreased further in the group of patients who received vincristine in combination with alkylating agents (decrease of 22.4%, P = 0.0049 and P < 0.0001, respectively), but in this group the CED was also increased significantly (P < 0.0001). Multivariate analysis, after CED adjustment, showed the persistence of a decrease in TFI correlated with vincristine administration (P = 0.02).

LIMITATIONS, REASONS FOR CAUTION

This is a descriptive study of testicular tissues obtained from (pre)pubertal boys who were at risk of infertility. The study population is quite heterogeneous, with a small number of patients in each sub-group. Our results are based on comparisons between patients receiving alkylating agents compared to patients receiving non-alkylating agents rather than chemotherapy-naive patients. The French national guidelines for fertility preservation in cancer patients recommend TTF before highly gonadotoxic treatment. Therefore, all the patients had received low- or moderate-risk gonadotoxic chemotherapy before TTF. Access to testicular tissue samples from chemotherapy-naive patients with comparable histological types of cancer was not possible. The functionality of spermatogonia and somatic cells could not be tested by transplantation or in vitro maturation due to limited sample sizes.

WIDER IMPLICATIONS OF THE FINDINGS

This study summarizes the spermatogonial quantity of (pre)pubertal boys prior to TTF. We confirmed a negative correlation between the cumulative exposure to alkylating agents and spermatogonial quantity. In addition, the synergistic use of vincristine in combination with alkylating agents showed a cumulative deleterious effect on the TFI. For patients for whom fertility preservation is indicated, TTF should be proposed for chemotherapy with a predicted CED above 4000 mg/m2. However, the data obtained from vincristine and carboplatin use should be confirmed in a subsequent study including more patients.

STUDY FUNDING/COMPETING INTEREST(S)

This study had financial support from a French national research grant PHRC No. 2008/071/HP obtained by the French Institute of Cancer and the French Healthcare Organization. The sponsors played no role in the study. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Lovastatin promotes the self-renewal of murine and primate spermatogonial stem cells

The spermatogonial stem cell (SSC) niche is critical for SSC maintenance and subsequent spermatogenesis. Numerous reproductive hazards impair the SSC niche, thereby resulting in aberrant SSC self-renewal and male infertility. However, promising agents targeting the impaired SSC niche to promote SSC self-renewal are still limited. Here, we screen out and assess the effects of Lovastatin on the self-renewal of mouse SSCs (mSSCs). Mechanistically, Lovastatin promotes the self-renewal of mSSCs and inhibits its inflammation and apoptosis through the regulation of isoprenoid intermediates. Remarkably, treatment by Lovastatin could promote the proliferation of undifferentiated spermatogonia in the male gonadotoxicity model generated by busulfan injection. Of note, we demonstrate that Lovastatin could enhance the proliferation of primate undifferentiated spermatogonia. Collectively, our findings uncover that lovastatin could promote the self-renewal of both murine and primate SSCs and have implications for the treatment of certain types of male infertility using small compounds.

The impact of vincristine on testicular development and function in childhood cancer

BACKGROUND

Increasing childhood cancer survival rates in recent decades have led to an increased focus on fertility as a long-term complication of cancer treatment. Male childhood cancer survivors often face compromised testicular function as a late effect of chemotherapy exposure, with no well-established options to prevent such damage and subsequent infertility. Despite vincristine being considered to be associated with low-gonadotoxic potential, in prepubertal rodents, it was recently shown to result in morphological alterations of the testis and in severely impaired fertility.

OBJECTIVE AND RATIONALE

This systematic review aimed to evaluate the effects of vincristine-containing regimens on human prepubertal testis with reference to testicular function and fertility in adulthood.

SEARCH METHODS

The systematic search of the literature was conducted according to PRISMA guidelines, and the study was registered with PROSPERO. PubMed and Scopus were searched for articles published in English between 01 January 1900 and 05 March 2021, with the search including 'chemotherapy', 'vincristine', 'prepubertal', 'testis', 'spermatogenesis' and related terms. Abstracts and full-text articles were screened and selected for, providing they met the inclusion criteria (≤12 years at treatment, exposure to vincristine-containing regimens and long-term fertility outcomes). Additional studies were identified via bibliography screening. Bias evaluation across included studies was conducted using the ROBINS-I tool, subdivided into assessment for confounding, participant selection, intervention classification, missing data, outcome measurements and selection of reported results.

OUTCOMES

Our initial search identified 288 articles of which 24 (8%; n = 7134 males) met all inclusion criteria. Control groups were included for 9/24 (38%) studies and 4/24 (17%) studies provided sub-analysis of the relative gonadotoxicity of vincristine-based agents. Primary outcome measures were: fertility and parenthood; semen analysis (World Health Organization criteria); and hormonal function and testicular volume. For the studies that performed vincristine sub-analysis, none reported negative associations with vincristine for the potential of siring a pregnancy, including the largest (n = 6224; hazard ratio = 0.56) controlled study. For semen analysis, no significant difference versus healthy controls was illustrated for mitotic inhibitors (including vincristine) following sub-analysis in one study (n = 143). For hormone analysis, a single study did not find significant impacts on spermatogenesis attributed to vincristine based on levels of FSH and semen analysis, which meant that its administration was unlikely to be responsible for the diminished testicular reserve; however, most of the studies were based on low numbers of patients receiving vincristine-containing chemotherapy. Analysis of bias demonstrated that studies which included vincristine exposure sub-analysis had a lower risk of bias when compared with cohorts which did not.

WIDER IMPLICATIONS

In contrast to recent findings in rodent studies, the limited number of clinical studies do not indicate gonadotoxic effects of vincristine following prepubertal exposure. However, given the relative lack of data from studies with vincristine sub-analysis, experimental studies involving vincristine exposure using human testicular tissues are warranted. Results from such studies could better inform paediatric cancer patients about their future fertility and eligibility for fertility preservation before initiation of treatment.

Review of the Function of the Hypothalamic-Pituitary-Gonadal Axis in Children and Adolescents with Cancer

The most common malignancies in childhood are leukaemias, brain tumours, lymphomas, neuroblastomas, soft tissue sarcomas and kidney tumours. At present, about 80% of childhood cancers can be treated successfully, which has significantly increased long-term survival. Concomitantly, adult gonadal function in childhood cancer survivors has become a concern. However, the immediate effect of cancer and its management on the reproductive axis function has received less attention. We conducted a review of the effects of malignancies and their treatments on the gonadal axis during childhood and adolescence. Some results are controversial, probably because the analyses do not distinguish between the malignancy types, their treatments and/or the age at treatment. However, there is agreement that cancer can partially affect gonadal function before treatment, as revealed by low circulating levels of inhibin B and anti-Müllerian hormone. Subsequently, chemotherapy transiently impairs the somatic component of the gonads (i.e. testicular Sertoli cells and ovarian granulosa cells) with normalization after treatment ends. The impact of chemotherapy may persist through adulthood after more intensive chemotherapy regimens, radiotherapy and conditioning for haematopoietic stem cell transplantation, when there is a severe impairment of the somatic component of the gonads or of the stem germ cells.

A multi-organ-chip co-culture of liver and testis equivalents: a first step toward a systemic male reprotoxicity model

STUDY QUESTION

Is it possible to co-culture and functionally link human liver and testis equivalents in the combined medium circuit of a multi-organ chip?

SUMMARY ANSWER

Multi-organ-chip co-cultures of human liver and testis equivalents were maintained at a steady-state for at least 1 week and the co-cultures reproduced specific natural and drug-induced liver-testis systemic interactions.

WHAT IS KNOWN ALREADY

Current benchtop reprotoxicity models typically do not include hepatic metabolism and interactions of the liver-testis axis. However, these are important to study the biotransformation of substances.

STUDY DESIGN, SIZE, DURATION

Testicular organoids derived from primary adult testicular cells and liver spheroids consisting of cultured HepaRG cells and hepatic stellate cells were loaded into separate culture compartments of each multi-organ-chip circuit for co-culture in liver spheroid-specific medium, testicular organoid-specific medium or a combined medium over a week. Additional multi-organ-chips (single) and well plates (static) were loaded only with testicular organoids or liver spheroids for comparison. Subsequently, the selected type of medium was supplemented with cyclophosphamide, an alkylating anti-neoplastic prodrug that has demonstrated germ cell toxicity after its bioactivation in the liver, and added to chip-based co-cultures to replicate a human liver-testis systemic interaction in vitro. Single chip-based testicular organoids were used as a control. Experiments were performed with three biological replicates unless otherwise stated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The metabolic activity was determined as glucose consumption and lactate production. The cell viability was measured as lactate dehydrogenase activity in the medium. Additionally, immunohistochemical and real-time quantitative PCR end-point analyses were performed for apoptosis, proliferation and cell-specific phenotypical and functional markers. The functionality of Sertoli and Leydig cells in testicular spheroids was specifically evaluated by measuring daily inhibin B and testosterone release, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

Co-culture in multi-organ chips with liver spheroid-specific medium better supported the metabolic activity of the cultured tissues compared to other media tested. The liver spheroids did not show significantly different behaviour during co-culture compared to that in single culture on multi-organ-chips. The testicular organoids also developed accordingly and produced higher inhibin B but lower testosterone levels than the static culture in plates with testicular organoid-specific medium. By comparison, testosterone secretion by testicular organoids cultured individually on multi-organ-chips reached a similar level as the static culture at Day 7. This suggests that the liver spheroids have metabolised the steroids in the co-cultures, a naturally occurring phenomenon. The addition of cyclophosphamide led to upregulation of specific cytochromes in liver spheroids and loss of germ cells in testicular organoids in the multi-organ-chip co-cultures but not in single-testis culture.

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The number of biological replicates included in this study was relatively small due to the limited availability of individual donor testes and the labour-intensive nature of multi-organ-chip co-cultures. Moreover, testicular organoids and liver spheroids are miniaturised organ equivalents that capture key features, but are still simplified versions of the native tissues. Also, it should be noted that only the prodrug cyclophosphamide was administered. The final concentration of the active metabolite was not measured.

WIDER IMPLICATIONS OF THE FINDINGS

This co-culture model responds to the request of setting up a specific tool that enables the testing of candidate reprotoxic substances with the possibility of human biotransformation. It further allows the inclusion of other human tissue equivalents for chemical risk assessment on the systemic level.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by research grants from the Scientific Research Foundation Flanders (FWO), Universitair Ziekenhuis Brussel (scientific fund Willy Gepts) and the Vrije Universiteit Brussel. Y.B. is a postdoctoral fellow of the FWO. U.M. is founder, shareholder and CEO of TissUse GmbH, Berlin, Germany, a company commercializing the Multi-Organ-Chip platform systems used in the study. The other authors have no conflict of interest to declare.

Effect of EPA on Neonatal Pig Sertoli Cells "In Vitro": A Possible Treatment to Help Maintain Fertility in Pre-Pubertal Boys Undergoing Treatment With Gonado-Toxic Therapies

The incidence of cancer in pre-pubertal boys has significantly increased and, it has been recognized that the gonado-toxic effect of the cancer treatments may lead to infertility. Here, we have evaluated the effects on porcine neonatal Sertoli cells (SCs) of three commonly used chemotherapy drugs; cisplatin, 4-Hydroperoxycyclophosphamide and doxorubicin. All three drugs induced a statistical reduction of 5-hydroxymethylcytosine in comparison with the control group, performed by Immunofluorescence Analysis. The gene and protein expression levels of GDNF, were significantly down-regulated after treatment to all three chemotherapy drugs comparison with the control group. Specifically, differences in the mRNA levels of GDNF were: 0,8200 ± 0,0440, 0,6400 ± 0,0140, 0,4400 ± 0,0130 fold change at 0.33, 1.66, and 3.33μM cisplatin concentrations, respectively (**p < 0.01 at 0.33 and 1.66 μM vs SCs and ***p < 0.001 at 3.33μM vs SCs); 0,6000 ± 0,0340, 0,4200 ± 0,0130 fold change at 50 and 100 μM of 4-Hydroperoxycyclophosphamide concentrations, respectively (**p < 0.01 at both these concentrations vs SCs); 0,7000 ± 0,0340, 0,6200 ± 0,0240, 0,4000 ± 0,0230 fold change at 0.1, 0.2 and 1 µM doxorubicin concentrations, respectively (**p < 0.01 at 0.1 and 0.2 μM vs SCs and ***p < 0.001 at 1 μM vs SCs). Differences in the protein expression levels of GDNF were: 0,7400 ± 0,0340, 0,2000 ± 0,0240, 0,0400 ± 0,0230 A.U. at 0.33, 1.66, and 3.33μM cisplatin concentrations, respectively (**p < 0.01 at both these concentrations vs SCs); 0,7300 ± 0,0340, 0,4000 ± 0,0130 A.U. at 50 and 100 μM of 4- Hydroperoxycyclophosphamide concentrations, respectively (**p < 0.01 at both these concentrations vs SCs); 0,6200 ± 0,0340, 0,4000 ± 0,0240, 0,3800 ± 0,0230 A.U. at 0.l, 0.2 and 1 µM doxorubicin concentrations, respectively (**p < 0.01 at 0.1 and 0.2 μM vs SCs and ***p < 0.001 at 1 μM vs SCs). Furthermore, we have demonstrated the protective effect of eicosapentaenoic acid on SCs only at the highest concentration of cisplatin, resulting in an increase in both gene and protein expression levels of GDNF (1,3400 ± 0,0280 fold change; **p < 0.01 vs SCs); and of AMH and inhibin B that were significantly recovered with values comparable to the control group. Results from this study, offers the opportunity to develop future therapeutic strategies for male fertility management, especially in pre-pubertal boys.

Paradoxical risk of reduced fertility after exposure of prepubertal mice to vincristine or cyclophosphamide at low gonadotoxic doses in humans

Cancer treatment can have long-term side effects in cured patients and infertility is one of them. Given the urgency of diagnosis in children with cancer, the toxicity of treatments on the gonad was overshadowed for a long time. In the present study, prepubertal mice were treated by vincristine or cyclophosphamide commonly used in acute leukaemia treatment. The prepubertal exposure to cyclophosphamide, at a low gonadotoxic dose in humans (< 3.5 g/m²), led to morphological alterations of prepubertal testicular tissue. An increased proportion of spermatozoa with hypocondensed chromatin and oxidized DNA associated with decreased fertility were uncovered at adulthood. Short- and long-term morphological alterations of the testicular tissue, disturbed progression of spermatogenesis along with increased proportions of isolated flagella and spermatozoa with fragmented DNA were evidenced in vincristine-treated mice. Moreover, the fertility of mice exposed to vincristine was severely affected despite being considered low-risk for fertility in humans. Paternal exposure to vincristine or cyclophosphamide before puberty had no impact on offspring development. Contrary to the current gonadotoxic risk classification, our results using a mouse model show that vincristine and cyclophosphamide (< 3.5 g/m²) present a high gonadotoxic risk when administered before the initiation of spermatogenesis.

A prospective study on the long-term outcome of prepubertal and pubertal boys undergoing testicular biopsy for fertility preservation prior to hematologic stem cell transplantation

BACKGROUND

Few studies have reported the long-term outcomes of prepubertal and pubertal boys undergoing testicular biopsy for fertility preservation (FP).

PROCEDURE

This prospective longitudinal study examined 21 boys (aged 1.5-14.5 years) who underwent testicular biopsy for FP prior to allogeneic (n = 20) or autologous (n = 1) hematological stem cell transplantation (HSCT) between 2003 and 2010. During counseling, pubertal boys were encouraged to produce a sperm sample by masturbation , while prepubertal boys were presented with surgical testicular tissue retrieval as an option for experimental FP. Clinical outcomes included postoperative complications, pubertal development, and sex-hormone levels. Survivors approaching adulthood were encouraged to provide semen samples.

RESULTS

Twenty boys, including 14 in prepuberty and six in early puberty (Tanner stage 2-3), underwent open testicular biopsies. Two pubertal biopsies contained mature sperms, which were cryopreserved. Testicular tissue was vitrified in the remaining 18 cases. One pubertal boy (Tanner stage 4) underwent percutaneous testicular sperm aspiration and sperms obtained were cryopreserved. Postoperative complications (hematoma or infection) were rare. Overall, 14 boys survived >5 years (mean follow-up after HSCT, 7.2 years) and 11 showed advanced puberty. Semen samples were provided by five boys and obtained sperm were cryopreserved from two. Individuals at adulthood had normal testosterone levels but subnormal testicular size, high follicle stimulating hormone, and low inhibin B and anti-Müllerian hormone levels.

CONCLUSION

No long-term risks were detected during continuous clinical follow-up. Experimental testicular biopsies for FP were well accepted by the patients and families, despite the absence of methods to use prepubertal tissue for fertility treatment.

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.

Differential seminal plasma proteome signatures of acute lymphoblastic leukemia survivors

With advances in therapeutic methods, there is a high survival rate among leukemia patients, of an extent more than 80%. However, chemotherapeutic drugs used to treat these patients have adverse effects on their overall health profile including fertility. The primary aim of this study was to identify differentially expressed proteins in seminal plasma of acute lymphoblastic leukemia (ALL) survivors compared to age-matched healthy controls, which can provide molecular basis of idiopathic infertility in such survivors. Differential proteome profiling was performed by 2D-differential in-gel electrophoresis, protein spots were identified by mass spectrometry and selective differentially expressed proteins (DEPs) were validated by western blotting and ELISA method. Out of eight DEPs identified, five proteins (isocitrate dehydrogenase 1, semenogelin 1, lactoferrin, prolactin-inducible protein, and human serum albumin) were upregulated and three (pepsinogen, prostate specific antigen and prostatic acid phosphatase) were downregulated. Expression profiles of these proteins are suggestive of reduction in semen quality in ALL survivors and can further be explored to determine their fertility status.

Oncofertility: Pharmacological Protection and Immature Testicular Tissue (ITT)-Based Strategies for Prepubertal and Adolescent Male Cancer Patients

While the incidence of cancer in children and adolescents has significantly increased over the last decades, improvements made in the field of cancer therapy have led to an increased life expectancy for childhood cancer survivors. However, the gonadotoxic effect of the treatments may lead to infertility. Although semen cryopreservation represents the most efficient and safe fertility preservation method for males producing sperm, it is not feasible for prepubertal boys. The development of an effective strategy based on the pharmacological protection of the germ cells and testicular function during gonadotoxic exposure is a non-invasive preventive approach that prepubertal boys could benefit from. However, the progress in this field is slow. Currently, cryopreservation of immature testicular tissue (ITT) containing spermatogonial stem cells is offered to prepubertal boys as an experimental fertility preservation strategy by a number of medical centers. Several in vitro and in vivo fertility restoration approaches based on the use of ITT have been developed so far with autotransplantation of ITT appearing more promising. In this review, we discuss the pharmacological approaches for fertility protection in prepubertal and adolescent boys and the fertility restoration approaches developed on the utilization of ITT.

DNA methylation and histone post-translational modifications in the mouse germline following in-vitro maturation of fresh or cryopreserved prepubertal testicular tissue

RESEARCH QUESTION

Do cryopreservation and in-vitro culture procedures affect the expression of DNA methyltransferases (DNMT) and histone-modifying enzymes, as well as the establishment of DNA methylation and histone post-translational modifications (PTM) in germ cells in prepubertal mouse testicular tissue?

DESIGN

This study investigated the expression of epigenetic modification enzymes, DNA methylation and histone PTM, and the spermatogenic progression after in-vitro maturation of fresh or cryopreserved mouse prepubertal testicular tissue. Fresh or cryopreserved testicular fragments from 6-7 days post-partum mice were cultured for 30 days in the presence of retinol with or without FSH.

RESULTS

The in-vitro maturation of fresh or cryopreserved tissue allowed the differentiation of spermatogonia into spermatozoa. Differences in the levels of transcripts encoding epigenetic modification enzymes (Dnmt1, Dnmt3a, Jarid1b, Src1, Sirt1, Hdac1) were found between 30-day tissue cultures and age-matched in-vivo controls. DNMT1/DNMT3a expression and the presence of 5-methylcytosine (5mC) were detected in spermatogonia and leptotene/zygotene spermatocytes in cultures. The relative 5mC fluorescence intensity was similar in spermatozoa produced in cultures of cryopreserved tissues or in vivo. H3K4me3, H3K9ac and H4K8ac were present in all germ cell types but differences in the proportion of germ cells containing these epigenetic marks were found after cultures.

CONCLUSIONS

Despite differences with the in-vivo situation, DNA methylation and histone methylation and acetylation occur in the mouse germline in in-vitro matured fresh or cryopreserved mouse prepubertal testicular tissue, and the expression of the enzymes catalysing these epigenetic modifications are maintained in vitro.

Acute Myeloid Leukemia Affects Mouse Sperm Parameters, Spontaneous Acrosome Reaction, and Fertility Capacity

Leukemia is one of the most common cancers in patients of reproductive age. It is well known that chemotherapy, used as anti-cancer therapy, adversely affects male fertility. Moreover, the negative effect of leukemia on sperm quality, even before chemotherapy treatment, has been reported. However, the mechanisms behind this disease's effect on sperm quality remains unknown. In this study, we examine the direct effect of leukemia and chemotherapy alone and in combination on sperm parameters and male fertility. For this, we developed an acute myeloid leukemia (AML) mouse model (mice were treated with AML cells C1498 and developed leukemia); these mice then received cytarabine chemotherapy. Our findings reveal a significant reduction in sperm concentration and motility and a significant increase in abnormal morphology and spontaneous acrosome reaction of the sperm following AML and chemotherapy treatment, alone and in combination. We also found a reduction in male fertility and the number of delivered offspring. Our results support previous findings that AML impairs sperm parameters and show for the first time that AML increases spontaneous acrosome reaction and decreases male fertility capacity and number of offspring.

Molecular Mechanisms and Signaling Pathways Involved in Sertoli Cell Proliferation

Sertoli cells are somatic cells present in seminiferous tubules which have essential roles in regulating spermatogenesis. Considering that each Sertoli cell is able to support a limited number of germ cells, the final number of Sertoli cells reached during the proliferative period determines sperm production capacity. Only immature Sertoli cells, which have not established the blood-testis barrier, proliferate. A number of hormonal cues regulate Sertoli cell proliferation. Among them, FSH, the insulin family of growth factors, activin, and cytokines action must be highlighted. It has been demonstrated that cAMP/PKA, ERK1/2, PI3K/Akt, and mTORC1/p70SK6 pathways are the main signal transduction pathways involved in Sertoli cell proliferation. Additionally, c-Myc and hypoxia inducible factor are transcription factors which participate in the induction by FSH of various genes of relevance in cell cycle progression. Cessation of proliferation is a pre-requisite to Sertoli cell maturation accompanied by the establishment of the blood-testis barrier. With respect to this barrier, the participation of androgens, estrogens, thyroid hormones, retinoic acid and opioids has been reported. Additionally, two central enzymes that are involved in sensing cell energy status have been associated with the suppression of Sertoli cell proliferation, namely AMPK and Sirtuin 1 (SIRT1). Among the molecular mechanisms involved in the cessation of proliferation and in the maturation of Sertoli cells, it is worth mentioning the up-regulation of the cell cycle inhibitors p21Cip1, p27Kip, and p19INK4, and of the gap junction protein connexin 43. A decrease in Sertoli cell proliferation due to administration of certain therapeutic drugs and exposure to xenobiotic agents before puberty has been experimentally demonstrated. This review focuses on the hormones, locally produced factors, signal transduction pathways, and molecular mechanisms controlling Sertoli cell proliferation and maturation. The comprehension of how the final number of Sertoli cells in adulthood is established constitutes a pre-requisite to understand the underlying causes responsible for the progressive decrease in sperm production that has been observed during the last 50 years in humans.

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.

Spermatogonial quantity in human prepubertal testicular tissue collected for fertility preservation prior to potentially sterilizing therapy

STUDY QUESTION

Does chemotherapy exposure (with or without alkylating agents) or primary diagnosis affect spermatogonial quantity in human prepubertal testicular tissue?

SUMMARY ANSWER

Spermatogonial quantity is significantly reduced in testes of prepubertal boys treated with alkylating agent therapies or with hydroxyurea for sickle cell disease.

WHAT IS KNOWN ALREADY

Cryopreservation of spermatogonial stem cells, followed by transplantation into the testis after treatment, is a proposed clinical option for fertility restoration in children. The key clinical consideration behind this approach is a sufficient quantity of healthy cryopreserved spermatogonia. However, since most boys with malignancies start therapy with agents that are not potentially sterilizing, they will have already received some chemotherapy before testicular tissue cryopreservation is considered.

STUDY DESIGN, SIZE, DURATION

We examined histological sections of prepubertal testicular tissue to elucidate whether chemotherapy exposure or primary diagnosis affects spermatogonial quantity. Quantity of spermatogonia per transverse tubular cross-section (S/T) was assessed in relation to treatment characteristics and normative reference values in histological sections of paraffin embedded testicular tissue samples collected from 32 consecutive boy patients (aged 6.3 ± 3.8 [mean ± SD] years) between 2014 and 2017, as part of the NORDFERTIL study, and in 14 control samples (from boys aged 5.6 ± 5.0 [mean ± SD] years) from an internal biobank.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Prepubertal boys in Sweden, Finland and Iceland who were facing treatments associated with a very high risk of infertility, were offered the experimental procedure of testicular cryopreservation. Exclusion criteria were testicular volumes >10 ml and high bleeding or infection risk. There were 18 patients with a diagnosis of malignancy and 14 patients a non-malignant diagnosis. While 20 patients had the testicular biopsy performed 1-45 days after chemotherapy, 12 patients had not received any chemotherapy. In addition, 14 testicular tissue samples of patients with no reported testicular pathology, obtained from the internal biobank of the Department of Pathology at Karolinska University Hospital, were included as control samples in addition to reference values obtained from a recently published meta-analysis. The quantity of spermatogonia was assessed by both morphological and immunohistochemical analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

The main finding was a significant reduction in spermatogonial cell counts in boys treated with alkylating agents or with hydroxyurea for sickle cell disease. The mean S/T values in boys exposed to alkylating agents (0.2 ± 0.3, n = 6) or in boys with sickle cell disease and exposed to hydroxyurea (0.3 ± 0.6, n = 6) were significantly lower (P = 0.003 and P = 0.008, respectively) than in a group exposed to non-alkylating agents or in biobank control samples (1.7 ± 1.0, n = 8 and 4.1 ± 4.6, n = 14, respectively). The mean S/T values of the testicular tissue samples included in the biobank control group and the patient group exposed to non-alkylating agents were within recently published normative reference values.

LIMITATIONS, REASONS FOR CAUTION

Normal testicular tissue samples included in this study were obtained from the internal biobank of Karolinska University Hospital. Samples were considered normal and included in the study if no testicular pathology was reported in the analysed samples. However, detailed information regarding previous medical treatments and testicular volumes of patients included in this biobank were not available.

WIDER IMPLICATIONS OF THE FINDINGS

This study summarizes, for the first time, spermatogonial quantity in a prepubertal patient cohort just before and after potentially sterilizing treatments. Boys facing cancer and cytotoxic therapies are regarded as the major group who will benefit from novel fertility preservation techniques. There are no previous reports correlating spermatogonial quantity to cumulative exposure to alkylating agents and anthracyclines (non-alkylating agents) and no information about the timing of cytotoxic exposures among this particular patient cohort. For prepubertal boys in whom fertility preservation is indicated, testicular tissue should be obtained before initiation of chemotherapy with alkylating agents, whilst for those with sickle cell disease and treated with hydroxyurea, this approach to fertility preservation may not be feasible.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from The Swedish Childhood Cancer Foundation (PR2016-0124; TJ2016-0093; PR2015-0073, TJ2015-0046) (J.-B.S. and K.J.), the Jane and Dan Olssons Foundation (2016-33) (J.-B.S.), the Finnish Cancer Society (K.J.), the Foundation for Paediatric Research (J.-B.S.), Kronprinsessan Lovisas Förening För Barnasjukvård/ Stiftelsen Axel Tielmans Minnesfond, Samariten Foundation (J.-B.S.), the Väre Foundation for Paediatric Cancer Research (K.J.) and the Swedish Research Council (2012-6352) (O.S.). R.T.M. was supported by a Wellcome Trust Fellowship (09822). J.P.A.-L. and M.K. were supported by the ITN Marie Curie program 'Growsperm' (EU-FP7-PEOPLE-2013-ITN 603568). The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

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

Aggressive chemotherapy in childhood often results in testicular damage and consequently jeopardizes future fertility. The presence of spermatogonial cells (SPGCs) in the testes of prepubertal cancer patient boys (PCPBs) can be used to develop future strategies for male fertility preservation. In the present study, we examined the presence of SPGCs in testes of chemotherapy-treated PCPBs and their ability to develop spermatogenesis in vitro using a three-dimensional culture system. Seven testicular biopsies were obtained from chemotherapy-treated PCPBs and one from a patient with β-thalassemia major. Isolated testicular cells were cultured in a methylcellulose culture system (MCS)-containing StemPro enriched with growth factors for 5-15 weeks. The presence of premeiotic, meiotic, and postmeiotic cells was examined by immunofluorescence staining and/or reverse transcription-polymerase chain reaction (RT-PCR) analysis. We observed SPGCs in the examined testicular biopsies. Isolated testicular cells cultured in MCS developed into colonies and contained premeiotic, meiotic, and postmeiotic cells. Furthermore, we identified sperm-like cells that had developed from testicular cells of a PCPB. Our results demonstrate, for the first time, the presence of biologically active SPGCs in testicular biopsies of chemotherapy-treated PCPBs and their capacity to develop in vitro to different stages of spermatogenesis, including the generation of sperm-like cells. This study may open the way for new therapeutic strategies for fertility preservation of PCPBs and for azoospermic patients.

Testicular damage in children and adolescents treated for malignancy: a short review

Significant advances have been made over recent decades in the treatment of childhood malignancies. These advances had an incredible cost, as an increasing number of young survivors suffer subfertility or infertility, because of the high sensitivity of testicular cells, especially the rapidly dividing germ cells, to cytotoxic drugs and irradiation. Therefore, the impact of treatment on future fertility is of significant concern, both to parents and patients. Assessment of fertility damage in childhood remains problematic. For post-pubertal males, semen analysis represents a good indicator of spermatogenesis and testicular function, and allows for sperm cryopreservation. The available method for prepubertal children is only gonadal tissue cryopreservation. This method is still experimental and raises ethical concerns. Ideally, a multidisciplinary team approach needs to be used in addressing the needs of fertility preservation for this population. Precise knowledge of these issues would help pediatric oncologists and endocrinologists to counsel their patients and inform them for factors and resources that may protect or preserve parenthood options in the future. (www.actabiomedica.it)

Chemotherapy drugs cyclophosphamide, cisplatin and doxorubicin induce germ cell loss in an in vitro model of the prepubertal testis

Long term survival rates for childhood cancers is steadily increasing, however cancer survivors can experience fertility problems as a consequence of chemotherapy treatment. This is particularly problematic for young boys, for whom no fertility preservation treatment is yet established. Here, we have determined the effects on prepubertal mouse testis of three commonly used chemotherapy drugs; cyclophosphamide (using its active metabolite phosphoramide mustard), cisplatin and doxorubicin, exposing testicular fragments to a clinically relevant range of concentrations in vitro. All three drugs induced a specific and highly significant loss of germ cells, including spermatogonial stem cells. In contrast, there was no significant effect on somatic cells, for either Sertoli or interstitial cells. Time course analysis of cleaved Caspase-3 expression showed a significant increase in apoptosis eight hours prior to a detectable decrease in germ cell numbers following exposure to phosphoramide mustard or cisplatin, although this pattern was not seen following doxorubicin-exposure. Moreover, analysis of DNA damage at 16 h showed increased γH2AX expression in response to all three drugs. Overall, results show that cisplatin, doxorubicin and cyclophosphamide all specifically induce loss of germ cells, including of spermatogonial stem cells, in the prepubertal mouse testis at concentrations relevant to human therapeutic exposures.

Fertility preservation issues in pediatric hematopoietic stem cell transplantation: practical approaches from the consensus of the Pediatric Diseases Working Party of the EBMT and the International BFM Study Group

Fertility preservation is an urgent challenge in the transplant setting. A panel of transplanters and fertility specialists within the Pediatric Diseases Working Party of the European Society for Blood and Marrow Transplantation (EBMT) and the International BFM Study Group provides specific guidelines. Patients and families should be informed of possible gender- and age-specific cryopreservation strategies that should be tailored according to the underlying disease, clinical condition and previous exposure to chemotherapy. Semen collection should be routinely offered to all postpubertal boys at the diagnosis of any disease requiring therapy that could potentially impair fertility. Testicular tissue collection might be offered to postpubertal boys; nevertheless, its use has been unsuccessful to date. Oocyte collection after hormonal hyperstimulation should be offered to postpubertal girls facing gonadotoxic therapies that could be delayed for the 2 weeks required for the procedure. Ovarian tissue collection could be offered to pre-/post-pubertal girls. Pregnancies have been reported after postpubertal ovarian tissue reimplantation; however, to date, no pregnancy has been reported after the reimplantation of prepubertal ovarian tissue or in vitro maturation of pre-/post-pubertal ovarian tissue. Possible future advances in reproductive medicine could change this scenario. Health authorities should prioritize fertility preservation projects in pediatric transplantation to improve patient care and quality of life.

Improvements in Clinical Trials Information Will Improve the Reproductive Health and Fertility of Cancer Patients

There are a number of barriers that result in cancer patients not being referred for oncofertility care, which include knowledge about reproductive risks of antineoplastic agents. Without this information, clinicians do not always make recommendations for oncofertility care. The objective of this study was to describe the level of reproductive information and recommendations that clinicians have available in clinical trial protocols regarding oncofertility management and follow-up, and the information that patients may receive in clinical trials patient information sheets or consent forms. A literature review of the 71 antineoplastic drugs included in the 68 clinical trial protocols showed that 68% of the antineoplastic drugs had gonadotoxic animal data, 32% had gonadotoxic human data, 83% had teratogenic animal data, and 32% had teratogenic human data. When the clinical trial protocols were reviewed, only 22% of the protocols reported the teratogenic risks and 32% of the protocols reported the gonadotoxic risk. Only 56% of phase 3 protocols had gonadotoxic information and 13% of phase 3 protocols had teratogenic information. Nine percent of the protocols provided fertility preservation recommendations and 4% provided reproductive information in the follow-up and survivorship period. Twenty-six percent had a section in the clinical trials protocol, which identified oncofertility information easily. When gonadotoxic and teratogenic effects of treatment were known, they were not consistently included in the clinical trial protocols and the lack of data for new drugs was not reported. Very few protocols gave recommendations for oncofertility management and follow-up following the completion of cancer treatment. The research team proposes a number of recommendations that should be required for clinicians and pharmaceutical companies developing new trials.

Irinotecan metabolite SN38 results in germ cell loss in the testis but not in the ovary of prepubertal mice

STUDY QUESTION

Does the Irinotecan metabolite 7-ethyl-10-hydroxycamptothecan (SN38) damage the gonads of male and female prepubertal mice?

SUMMARY ANSWER

The Irinotecan metabolite SN38 reduces germ cell numbers within the seminiferous tubules of mouse testes at concentrations that are relevant to cancer patients, while in contrast it has little if any effect on the female germ cell population.

WHAT IS KNOWN ALREADY

Little is known about the role of the chemotherapeutic agent Irinotecan on female fertility, with only one article to date reporting menopausal symptoms in perimenopausal women treated with Irinotecan, while no data are available either on adult male fertility or on the impact of Irinotecan on the subsequent fertility of prepubertal cancer patients, female or male.

STUDY DESIGN SIZE, DURATION

Male and female gonads were obtained from postnatal day 5 C57BL/6 mice and exposed in vitro to a range of concentrations of the Irinotecan metabolite SN38: 0.002, 0.01, 0.05, 0.1 or 1 µg ml^–1 for the testis and 0.1, 1, 2.5 or 5 µg ml^–1 for the ovary, with treated gonads compared to control gonads not exposed to SN38. SN38 was dissolved in 0.5% dimethyl sulfoxide, with controls exposed to the same concentration of diluent. The number of testis fragments used for each analysis ranged between 3 and 9 per treatment group, while the number of ovaries used for each analysis ranged between 4 and 12 per treatment group.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Neonatal mouse gonads were developed in vitro, with tissue analysed at the end of the 4–6 day culture period, following immunofluorescence or hematoxylin and eosin staining. Statistical analyses were performed using one-way ANOVA followed by Bonferroni post-hoc test for normally distributed data and Kruskal-Wallis test followed by Dunns post-test for non-parametric data.

MAIN RESULTS AND THE ROLE OF CHANCE

Abnormal testis morphology was observed when tissues were exposed to SN38, with a smaller seminiferous tubule diameter at the highest concentration of SN38 (1 µg ml⁻¹, p < 0.001 versus control) and increased number of Sertoli cell-only tubules at the two highest concentrations of SN38 (0.1 µg ml⁻¹, p < 0.001; 1 µg ml⁻¹, p < 0.0001, both versus control). Within seminiferous tubules, a dose response decrease was observed in both germ cell number (mouse vasa homologue (MVH)-positive cells) and in proliferating cell number (bromodeoxyuridine (BrdU)-positive cells), with significance reached at the two highest concentrations of SN38 (0.1 µg ml⁻¹, p < 0.01 for both; 1 µg ml⁻¹, p < 0.001-MVH, p < 0.01-BrdU; all versus control). No change was seen in protein expression of the apoptotic marker cleaved caspase 3. Double immunofluorescence showed that occasional proliferating germ cells were present in treated testes, even after exposure to the highest drug concentration. When prepubertal ovaries were treated with SN38, no effect was seen on germ cell number, apoptosis or cell proliferation, even after exposure to the highest drug concentrations.

LIMITATIONS REASONS FOR CAUTION

As with any study using in vitro experiments with an experimental animal model, caution is required when extrapolating the present findings to humans. Differences between human and mouse spermatogonial development also need to be considered when assessing the effect of chemotherapeutic exposure. However, the prepubertal testes and ovaries used in the present studies contain germ cell populations that are representative of those found in prepubertal patients, and experimental tissues were exposed to drug concentrations within the range found in patient plasma.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings demonstrate that the prepubertal mouse ovary is relatively insensitive to exposure to the Irinotecan metabolite SN38, while it induces a marked dose-dependent sensitivity in the testicular germ cell population. The study identifies the importance of further investigation to identify the risk of infertility in young male cancer patients treated with Irinotecan.

LARGE SCALE DATA

None.

STUDY FUNDING AND COMPETING INTEREST(S)

Work supported by Medical Research Grant (MRC) grant G1002118 and Children with Cancer UK grant 15-198. The authors declare that there is no conflict of interest that could prejudice the impartiality of the present research.

Progress and Prospects in Pediatric Leukemia

Pediatric leukemia is the single most common malignancy affecting children, representing up to 30% of all pediatric cancers. Dramatic improvements in survival for acute lymphoblastic leukemia (ALL) have taken place over the past 4 decades with outcomes approaching 90% in the latest studies. However, progress has been slower for myeloid leukemia and certain subgroups like infant ALL, adolescent/young adult ALL, and relapsed ALL. Recent advances include recognition of molecularly defined subgroups, which has ushered in precision medicine approaches. We discuss the current understanding of the biology of the various childhood leukemias, recent advances in research, and future challenges in this field.

Is the protein expression window during testicular development affected in patients at risk for stem cell loss?

STUDY QUESTION

Is the protein expression window during testicular development affected in prepubertal patients at risk for stem cell loss?

SUMMARY ANSWER

Nuclear ubiquitin carboxyl-terminal esterase L1 (UCHL1) expression in Sertoli cells and interstitial expression of inhibin α (INHA), sex-determining region Y-box 9 (SOX9) and steroidogenic acute regulatory protein (STAR) was affected in patients with Klinefelter syndrome.

WHAT IS KNOWN ALREADY

Some patients undergoing testicular tissue banking have already been treated before the testis biopsy is taken. These treatments include chemotherapy or hydroxyurea, which can have an influence on the stem cell number and function. A germinal loss occurs in Klinefelter patients, but its cause is currently unknown.

STUDY DESIGN, SIZE, DURATION

Parrafin-embedded testicular tissue from 5 fetuses, 25 prepubertal patients and 5 adults was used to characterize the spatial and temporal distribution of different testicular marker proteins during testicular development. Expression of the markers was evaluated in germ cells, Sertoli cell and interstitial cells. The integrity of this time window was analyzed in patients at risk for germ cell loss: patients treated with hydroxyurea (n = 7), patients treated with chemotherapy (n = 6) and patients affected by Klinefelter syndrome (n = 5).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Immunohistochemistry was performed in normal fetal, prepubertal and adult testicular tissue to set up a timeline for the expression of melanoma antigen family A4 (MAGE-A4), ubiquitin carboxyl-terminal esterase L1 (UCHL1), octamer-binding transcription factor 4 (OCT4), stage-specific embryonic antigen-4 (SSEA4), homeobox protein NANOG, INHA, anti-Müllerian hormone, androgen receptor (AR), SOX9 and STAR. The established timeline was used to evaluate whether the expression of these markers was altered in patients at risk for germ cell loss (patients treated for sickle cell disease (hydroxyurea) or cancer (chemotherapy) and patients with Klinefelter syndrome).

MAIN RESULTS AND THE ROLE OF CHANCE

A protein expression timeline was created using different markers expressed in different testicular cell types. Less positive tubules and less positive cells per tubule were observed for MAGE-A4 and UCHL1 expression in the KS compared with the non-treated group (P < 0.01). Higher nuclear UCHL1 Sertoli cell expression was observed in the KS group compared with the non-treated group (P < 0.05). Higher interstitial expression of INHA (P < 0.05), SOX9 (P < 0.01) and STAR (P < 0.05) was observed in KS compared with the non-treated group.

LIMITATIONS, REASONS FOR CAUTION

Important age variations exist in the prepubertal groups. Therefore, data were represented in three age groups. However, owing to the limited access to prepubertal tissue, no statistical comparison was possible between these groups. For the Klinefelter group, tissue was only available from patients older than 12 years.

WIDER IMPLICATIONS OF THE FINDINGS

The expression timeline can add knowledge to the process of spermatogenesis and be used to evaluate altered protein patterns in patients undergoing potentially gonadotoxic treatments, to monitor spermatogenesis established in vitro and to unravel causes of germ cell loss in Klinefelter patients.

A European perspective on testicular tissue cryopreservation for fertility preservation in prepubertal and adolescent boys

STUDY QUESTION

What clinical practices, patient management strategies and experimental methods are currently being used to preserve and restore the fertility of prepubertal boys and adolescent males?

SUMMARY ANSWER

Based on a review of the clinical literature and research evidence for sperm freezing and testicular tissue cryopreservation, and after consideration of the relevant ethical and legal challenges, an algorithm for the cryopreservation of sperm and testicular tissue is proposed for prepubertal boys and adolescent males at high risk of fertility loss.

WHAT IS KNOWN ALREADY

A known late effect of the chemotherapy agents and radiation exposure regimes used to treat childhood cancers and other non-malignant conditions in males is the damage and/or loss of the proliferating spermatogonial stem cells in the testis. Cryopreservation of spermatozoa is the first line treatment for fertility preservation in adolescent males. Where sperm retrieval is impossible, such as in prepubertal boys, or it is unfeasible in adolescents prior to the onset of ablative therapies, alternative experimental treatments such as testicular tissue cryopreservation and the harvesting and banking of isolated spermatogonial stem cells can now be proposed as viable means of preserving fertility.

STUDY DESIGN, SIZE, DURATION

Advances in clinical treatments, patient management strategies and the research methods used to preserve sperm and testicular tissue for prepubertal boys and adolescents were reviewed. A snapshot of the up-take of testis cryopreservation as a means to preserve the fertility of young males prior to December 2012 was provided using a questionnaire.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A comprehensive literature review was conducted. In addition, survey results of testis freezing practices in young patients were collated from 24 European centres and Israeli University Hospitals.

MAIN RESULTS AND THE ROLE OF CHANCE

There is increasing evidence of the use of testicular tissue cryopreservation as a means to preserve the fertility of pre- and peri-pubertal boys of up to 16 year-old. The survey results indicate that of the 14 respondents, half of the centres were actively offering testis tissue cryobanking as a means of safeguarding the future fertility of boys and adolescents as more than 260 young patients (age range less than 1 year old to 16 years of age), had already undergone testicular tissue retrieval and storage for fertility preservation. The remaining centres were considering the implementation of a tissue-based fertility preservation programme for boys undergoing oncological treatments.

LIMITATIONS, REASONS FOR CAUTION

The data collected were limited by the scope of the questionnaire, the geographical range of the survey area, and the small number of respondents.

WIDER IMPLICATIONS OF THE FINDINGS

The clinical and research questions identified and the ethical and legal issues raised are highly relevant to the multi-disciplinary teams developing treatment strategies to preserve the fertility of prepubertal and adolescent boys who have a high risk of fertility loss due to ablative interventions, trauma or genetic pre-disposition.

Testicular function and fertility preservation after treatment for haematological cancer

PURPOSE OF REVIEW

Treatment for high-risk or relapsed haematological malignancy with haematopoietic stem cell transplantation is known to cause infertility. Today, there are no established options for fertility preservation in pre-pubertal boys. This review aims to describe how therapy for haematological malignancy in childhood affects male fertility, and to summarize recent developments for fertility preservation in these patients.

RECENT FINDINGS

Eventual recovery of spermatogenesis is probable after chemotherapy-based conditioning for haematopoietic stem cell transplantation. However, conditioning with total body irradiation is associated with a very high risk of permanent infertility. For high-risk patients, auto-transplantation of cryopreserved testicular tissue or cells might represent an approach for fertility preservation; however, contamination of testis tissue with malignant cells may prevent their subsequent reintroduction into patients. Recent progress using in-vitro differentiation of germ cells combined with assisted reproductive techniques may, in the future, represent a suitable alternative to retransplantation.

SUMMARY

Particular care must be taken when assessing infertility risk in patients with haematological malignancy as reclassification to high risk may significantly increase the likelihood of treatment-related gonadotoxicity. Importantly, development of fertility preservation strategies in such high-risk patients must also take into account specific risks for haematological cancers including cancer cell contamination.

Adult stem cell transplantation: is gender a factor in stemness?

Cell therapy now constitutes an important area of regenerative medicine. The aging of the population has mandated the discovery and development of new and innovative therapeutic modalities to combat devastating disorders such as stroke. Menstrual blood and Sertoli cells represent two sources of viable transplantable cells that are gender-specific, both of which appear to have potential as donor cells for transplantation in stroke. During the subacute phase of stroke, the use of autologous cells offers effective and practical clinical application and is suggestive of the many benefits of using the aforementioned gender-specific cells. For example, in addition to being exceptionally immunosuppressive, testis-derived Sertoli cells secrete many growth and trophic factors and have been shown to aid in the functional recovery of animals transplanted with fetal dopaminergic cells. Correspondingly, menstrual blood cells are easily obtainable and exhibit angiogenic characteristics, proliferative capability, and pluripotency. Of further interest is the ability of menstrual blood cells, following transplantation in stroke models, to migrate to the infarct site, secrete neurotrophic factors, regulate the inflammatory response, and be steered towards neural differentiation. From cell isolation to transplantation, we emphasize in this review paper the practicality and relevance of the experimental and clinical use of gender-specific stem cells, such as Sertoli cells and menstrual blood cells, in the treatment of stroke.

The battle of the sexes for stroke therapy: female- versus male-derived stem cells

Cell therapy is a major discipline of regenerative medicine that has been continually growing over the last two decades. The aging of the population necessitates discovery of therapeutic innovations to combat debilitating disorders, such as stroke. Menstrual blood and Sertoli cells are two gender-specific sources of viable transplantable cells for stroke therapy. The use of autologous cells for the subacute phase of stroke offers practical clinical application. Menstrual blood cells are readily available, display proliferative capacity, pluripotency and angiogenic features, and, following transplantation in stroke models, have the ability to migrate to the infarct site, regulate the inflammatory response, secrete neurotrophic factors, and have the possibility to differentiate into neural lineage. Similarly, the testis-derived Sertoli cells secrete many growth and trophic factors, are highly immunosuppressive, and exert neuroprotective effects in animal models of neurological disorders. We highlight the practicality of experimental and clinical application of menstrual blood cells and Sertoli cells to treat stroke, from cell isolation and cryopreservation to administration.

Spermatogonial stem cell preservation and transplantation: from research to clinic

STUDY QUESTION

What issues remain to be solved before fertility preservation and transplantation can be offered to prepubertal boys?

SUMMARY ANSWER

The main issues that need further investigation are malignant cell decontamination, improvement of in vivo fertility restoration and in vitro maturation.

WHAT IS KNOWN ALREADY

Prepubertal boys who need gonadotoxic treatment might render sterile for the rest of their life. As these boys do not yet produce sperm cells, they cannot benefit from sperm banking. Spermatogonial stem cell (SSC) banking followed by autologous transplantation has been proposed as a fertility preservation strategy. But before this technique can be applied in the clinic, some important issues have to be resolved.

STUDY DESIGN, SIZE DURATION

Original articles as well as review articles published in English were included in a search of the literature.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Relevant studies were selected by an extensive Medline search. Search terms were fertility preservation, cryopreservation, prepubertal, SSC, testis tissue, transplantation, grafting and in vitro spermatogenesis. The final number of studies selected for this review was 102.

MAIN RESULTS AND THE ROLE OF CHANCE

Cryopreservation protocols for testicular tissue have been developed and are already being used in the clinic. Since the efficiency and safety of SSC transplantation have been reported in mice, transplantation methods are now being adapted to the human testes. Very recently, a few publications reported on in vitro spermatogenesis in mice, but this technique is still far from being applied in a clinical setting.

LIMITATIONS, REASONS FOR CAUTION

Using tissue from cancer patients holds a potential risk for contamination of the collected testicular tissue. Therefore, it is of immense importance to separate malignant cells from the cell suspension before transplantation. Because biopsies obtained from young boys are small and contain only few SSCs, propagation of these cells in vitro will be necessary.

WIDER IMPLICATIONS OF THE FINDINGS

The ultimate use of the banked tissue will depend on the patient's disease. If the patient was suffering from a non-malignant disease, tissue grafting might be offered. In cancer patients, decontaminated cell suspensions will be injected in the testis. For patients with Klinefelter syndrome, the only option would be in vitro spermatogenesis. However, at present, restoring fertility in cancer and Klinefelter patients is not yet possible.

STUDY FUNDING/COMPETING INTEREST(S)

Research Foundation, Flanders (G.0385.08 to H.T.), the Institute for the Agency for Innovation, Belgium (IWT/SB/111245 to E.G.), the Flemish League against Cancer (to E.G.), Kom op tegen kanker (G.0547.11 to H.T.) and the Fund Willy Gepts (to HT). E.G. is a Postdoctoral Fellow of the FWO, Research Foundation, Flanders. There are no conflicts of interest.

Clinical review: Present and future prospects of male fertility preservation for children and adolescents

CONTEXT

Rapid progress in fertility preservation strategies has led to the investigation of ways in which fertile gametes could be generated from cryopreserved immature testicular tissue. Childhood cancer patients remain the major group that can benefit from these techniques. Other potential candidates include patients undergoing gonadectomy and patients with Klinefelter's syndrome and cryptorchid testes. This review aims to present an overview of the current state of knowledge in experimental germ cell transplantation, testicular tissue transplantation, and germ cell culture as fertility preservation methods for males.

METHODOLOGY

We included English articles published in PubMed as well as personal files with the focus on studies including human or nonhuman material.

MAIN FINDINGS

Germ cell and testicular tissue transplantation demonstrate clinical options to mature germ cells from immature primate testicular tissue. The most promising approach involves autologous grafting of immature testicular tissue, whereas germ cell maturation in vitro provides the best strategies to overcome problems of cancer contamination in cryopreserved testicular tissue. Three-dimensional and organ culture systems offer the possibility to differentiate immature male germ cells up to the stage of elongated spermatids. Further characterization of early germ cell development in humans is needed to modify these systems for clinical use.

Oncofertility and the male cancer patient

OPINION STATEMENT

Oncofertility as a discipline plays an important, adjunctive role in the treatment of male patients with cancer. Despite recommendations by the American Society of Clinical Oncology, many clinicians managing malignancies in males fail to consistently incorporate fertility preservation as a routine aspect of health care. Providers involved in the treatment of oncologic patients should have an awareness of the impact of their prescribed treatments on reproductive potential, just as they would be knowledgeable of the potential deleterious effects of cancer therapies on vital organs such as the kidneys, lungs, and liver. Providers should then have a discussion with their patients regarding these potential adverse therapeutic effects or consult a fertility preservation specialist to discuss these matters and fertility preservation options with the patient. Cryopreservation of sperm remains an excellent option for male fertility preservation as it is readily available and results in storage of viable gametes for future use in the event of post treatment infertility. With the use of assisted reproductive techniques (ART), cryopreserved sperm may ultimately result in successful paternity, even in the setting of very low numbers of stored sperm. While sperm cryopreservation is usually an option for adolescent and adult males, fertility preservation in pre-pubertal males presents a more challenging problem. To date, no clinically proven methods are available to preserve fertility in these males. However, some centers do offer experimental protocols under the oversight of an IRB, such as testicular tissue cryopreservation in these males. The hope is that one day science will provide a mechanism for immature germ cells from the testicular tissue of these patients to be used in vivo or in vitro to facilitate reproduction. In closing, studies have shown that the patient's regard for his provider is enhanced when the issue fertility preservation is raised. While oncologic care is often fraught with time constraints and acute medical concerns, fertility preservation care in the male can typically be administered quickly and without disruption of the overall plan of care.

Fertility preservation in young cancer patients

As a result of advances in treatment, almost 80% of children and adolescents who receive a diagnosis of cancer become long-term survivors. The increased survival rate of children and adolescents with cancer has resulted in a major interest in the long-term effects of cancer treatment on the possibility for future fertility. Currently established methods for the preservation of fertility are available only for pubertal males and females. Pubertal male cancer patients should be encouraged to freeze numerous sperm samples even when sperm count and motility are poor. In these cases, intracytoplasmic sperm injection is a powerful technique compared with intrauterine insemination since thawed sperm samples with poor parameters can produce relatively high fertilization rates resulting in normal pregnancies and deliveries. Married pubertal women should be proposed ovulation induction, follicular aspiration, and fertilization with husband sperm. Single women could benefit from vitrification of oocytes. This requires a delay of about 3 weeks in the commencement of chemotherapy to enable follicular growth. Fertility preservation for prepubertal patients is more of a problem. Young girls could be offered cryopreservation of gametes in the gonadal tissue. Cryopreservation of testicular tissue was suggested for fertility preservation for young boys, but this method is totally experimental and not currently offered. Discussing future fertility is part of the consultation of young female and male patients facing potentially gonadotoxic cancer therapy. It is the role of reproductive specialists to create various options in their laboratory to preserve fertility potential of cancer patients.

High risk of azoospermia in men treated for childhood cancer

Childhood cancer survivors (CCS) have an increased risk of impaired spermatogenesis, but data regarding the disease- and treatment-related risk factors of azoospermia are scarce. Such information is crucial both for counselling CCS and for selecting patients for testicular tissue cryopreservation. The proportion of azoospermic men in CCS was 18% [95% confidence interval (CI): 12-26], specifically for leukaemias (19%; 95% CI: 5.5-42), Hodgkin's disease (53%; 95% CI: 29-76), non-Hodgkin's lymphoma (11%; 95% CI: 0.28-48) and testicular cancer (11%; 95% CI: 0.28-48). In CCS treated with high doses of alkylating agents, the proportion of azoospermic men was 80% (95% CI: 28-99) and if radiotherapy was used additionally, the proportion was 64% (95% CI: 35-87). In CCS with subnormal Inhibin B levels, the proportion of azoospermic men was 66% (95% CI: 47-81) and for those with elevated follicle-stimulating hormone (FSH) levels, the proportion was 50% (95% CI: 35-67). Among CCS with subnormal testicular volume (≤ 24 mL), azoospermia was found in 61% (95% CI: 39-80) of the cases. Most childhood cancer diagnoses are associated with an increased risk of azoospermia, especially in CCS receiving testicular irradiation, high doses of alkylating drugs and other types of cytotoxic treatment, if combined with irradiation. Inhibin B, FSH and testicular volume can be used as predictors for the risk of azoospermia.

Incorporating fertility preservation into the care of young oncology patients

As the number of cancer survivors continues to increase, oncologists are faced with the challenge of providing cancer therapy to patients who may 1 day want to have children. Yet, gonadotoxic cancer treatments can compromise future fertility, either temporarily or permanently. There are established means of preserving fertility before cancer treatment; specifically, sperm cryopreservation for men and in vitro fertilization and embryo cryopreservation for women. Several innovative techniques are being actively investigated, including oocyte and ovarian follicle cryopreservation, ovarian tissue transplantation, and in vitro follicle maturation, which may expand the number of fertility preservation choices for young cancer patients. Fertility preservation may also require some modification of cancer therapy; thus, patients' wishes regarding future fertility and available fertility preservation alternatives should be discussed before initiation of therapy. This commentary provides an overview of the range of fertility preservation options currently available and under development, using case-based discussions to illustrate ways in which fertility preservation can be incorporated into oncology care. Cases involving breast cancer, testicular cancer, and rectal cancer are described to illustrate fertility issues experienced by male and female patients, as well as to provide examples of strategies for modifying surgical, medical, and radiation therapy to spare fertility. Current guidelines in oncology and reproductive medicine are also reviewed to underscore the importance of communicating fertility preservation options to young patients with cancer.

Sperm analysis of patients after successful treatment of childhood acute lymphoblastic leukemia with chemotherapy

Survivors of childhood acute lymphoblastic leukemia (ALL) treated with radiotherapy are at risk for impaired fertility. Whether chemotherapy alone is also long-term gonadotoxic is unclear. We assessed gonadal function in 11 male ALL-survivors treated with the same chemotherapy regimen and compared sperm analysis to healthy men. While sex hormone levels were normal in all subjects, 5/11 survivors showed pathological sperm concentration and 4/11 a decreased total sperm count compared to WHO criteria. Compared to healthy controls, all quantitative parameters in semen analysis of survivors were decreased. This suggests that treatment with chemotherapeutic agents alone, even in moderate doses, might have a gonadotoxic effect.