Granulocyte-colony stimulating factor does not prevent in vitro cisplatin-induced germ cell reduction in immature human and mouse testis

BACKGROUND

Currently there are no established fertility preservation options for pre-pubertal boys facing cancer treatment. Granulocyte-colony stimulating factor (G-CSF) treatment has been proposed to be chemoprotective against spermatogonial cell loss in an alkylating chemotherapy model of busulfan treated adult mice. Having previously shown that exposure to the alkylating-like chemotherapy cisplatin resulted in a reduction in germ cell numbers in immature human testicular tissues, we here investigate whether G-CSF would prevent cisplatin-induced germ cell loss in immature human and mouse (fetal and pre-pubertal) testicular tissues.

METHODS

Organotypic in vitro culture systems were utilised to determine the effects of clinically-relevant concentrations of G-CSF in cisplatin-exposed immature testicular tissues. Human fetal (n = 14 fetuses) and mouse pre-pubertal (n = 4 litters) testicular tissue pieces were cultured and exposed to cisplatin or vehicle control for 24 hrs and analysed at 72 and 240 hrs post-exposure. Combined G-CSF and cisplatin exposure groups explored varying concentrations and duration of G-CSF supplementation to the culture medium (including groups receiving G-CSF before, during and after cisplatin exposure). In addition, effects of G-CSF supplementation alone were investigated. Survival of total germ cell and sub-populations were identified by expression of AP2γ and MAGE-A4 for human gonocytes and (pre)spermatogonia, respectively, and MVH and PLZF, for mouse germ cells and putative spermatogonial stem cells (SSCs) respectively, were quantified.

RESULTS

Exposure to cisplatin resulted in a reduced germ cell number in human fetal and mouse pre-pubertal testicular tissues at 240 hrs post-exposure. Germ cell number was not preserved by combined exposure with G-CSF using any of the exposure regimens (prior to, during or after cisplatin exposure). Continuous supplementation with G-CSF alone for 14 days did not change the germ cell composition in either human or mouse immature testicular tissues.

CONCLUSIONS

This study demonstrates that exposure to G-CSF does not prevent cisplatin-induced germ cell loss in immature human and mouse testicular tissues in an in vitro system.

Identification of a window of androgen sensitivity for somatic cell function in human fetal testis cultured ex vivo

BACKGROUND

Reduced androgen action during early fetal development has been suggested as the origin of reproductive disorders comprised within the testicular dysgenesis syndrome (TDS). This hypothesis has been supported by studies in rats demonstrating that normal male development and adult reproductive function depend on sufficient androgen exposure during a sensitive fetal period, called the masculinization programming window (MPW). The main aim of this study was therefore to examine the effects of manipulating androgen production during different timepoints during early human fetal testis development to identify the existence and timing of a possible window of androgen sensitivity resembling the MPW in rats.

METHODS

The effects of experimentally reduced androgen exposure during different periods of human fetal testis development and function were examined using an established and validated human ex vivo tissue culture model. The androgen production was reduced by treatment with ketoconazole and validated by treatment with flutamide which blocks the androgen receptor. Testicular hormone production ex vivo was measured by liquid chromatography-tandem mass spectrometry or ELISA assays, and selected protein markers were assessed by immunohistochemistry.

RESULTS

Ketoconazole reduced androgen production in testes from gestational weeks (GW) 7-21, which were subsequently divided into four age groups: GW 7-10, 10-12, 12-16 and 16-21. Additionally, reduced secretion of testicular hormones INSL3, AMH and Inhibin B was observed, but only in the age groups GW 7-10 and 10-12, while a decrease in the total density of germ cells and OCT4⁺ gonocytes was found in the GW 7-10 age group. Flutamide treatment in specimens aged GW 7-12 did not alter androgen production, but the secretion of INSL3, AMH and Inhibin B was reduced, and a reduced number of pre-spermatogonia was observed.

CONCLUSIONS

This study showed that reduced androgen action during early development affects the function and density of several cell types in the human fetal testis, with similar effects observed after ketoconazole and flutamide treatment. The effects were only observed within the GW 7-14 period-thereby indicating the presence of a window of androgen sensitivity in the human fetal testis.

Cisplatin Effects on the Human Fetal Testis - Establishing the Sensitive Period for (Pre)Spermatogonial Loss and Relevance for Fertility Preservation in Pre-Pubertal Boys

Background

Exposure to chemotherapy during childhood can impair future fertility. Studies using in vitro culture have shown exposure to platinum-based alkylating-like chemotherapy reduces the germ cell number in the human fetal testicular tissues. We aimed to determine whether effects of exposure to cisplatin on the germ cell sub-populations are dependent on the gestational age of the fetus and what impact this might have on the utility of using human fetal testis cultures to model chemotherapy exposure in childhood testis.

Methods

We utilised an in vitro culture system to culture pieces of human fetal testicular tissues (total n=23 fetuses) from three different gestational age groups (14-16 (early), 17-19 (mid) and 20-22 (late) gestational weeks; GW) of the second trimester. Tissues were exposed to cisplatin or vehicle control for 24 hours, analysing the tissues 72 and 240 hours post-exposure. Number of germ cells and their sub-populations, including gonocytes and (pre)spermatogonia, were quantified.

Results

Total germ cell number and number of both germ cell sub-populations were unchanged at 72 hours post-exposure to cisplatin in the testicular tissues from fetuses of the early (14-16 GW) and late (20-22 GW) second trimester. In the testicular tissues from fetuses of mid (17-19 GW) second trimester, total germ cell and gonocyte number were significantly reduced, whilst (pre)spermatogonial number was unchanged. At 240 hours post-exposure, the total number of germ cells and that of both sub-populations was significantly reduced in the testicular tissues from fetuses of mid- and late-second trimester, whilst germ cells in early-second trimester tissues were unchanged at this time-point.

Conclusions

In vitro culture of human fetal testicular tissues can be a useful model system to investigate the effects of chemotherapy-exposure on germ cell sub-populations during pre-puberty. Interpretation of the results of such studies in terms of relevance to later (infant and pre-pubertal) developmental stages should take into account the changes in germ cell composition and periods of germ cell sensitivity in the human fetal testis.

Maintenance of Sertoli Cell Number and Function in Immature Human Testicular Tissues Exposed to Platinum-Based Chemotherapy-Implications for Fertility Restoration

Background: Retrospective studies in adult survivors of childhood cancer show long-term impacts of exposure to alkylating chemotherapy on future fertility. We recently demonstrated germ cell loss in immature human testicular tissues following exposure to platinum-based chemotherapeutic drugs. This study investigated the effects of platinum-based chemotherapy exposure on the somatic Sertoli cell population in human fetal and pre-pubertal testicular tissues. Methods: Human fetal (n = 23; 14-22 gestational weeks) testicular tissue pieces were exposed to cisplatin (0.5 or 1.0 μg/ml) or vehicle for 24 h in vitro and analysed 24-240 h post-exposure or 12 weeks after xenografting. Human pre-pubertal (n = 10; 1-12 years) testicular tissue pieces were exposed to cisplatin (0.5 μg/ml), carboplatin (5 μg/ml) or vehicle for 24 h in vitro and analysed 24-240 h post-exposure; exposure to carboplatin at 10-times the concentration of cisplatin reflects the relative clinical doses given to patients. Immunohistochemistry was performed for SOX9 and anti-Müllerian hormone (AMH) expression and quantification was carried out to assess effects on Sertoli cell number and function respectively. AMH and inhibin B was measured in culture medium collected post-exposure to assess effects on Sertoli cell function. Results: Sertoli cell (SOX9+ve) number was maintained in cisplatin-exposed human fetal testicular tissues (7,647 ± 459 vs. 7,767 ± 498 cells/mm2; p > 0.05) at 240 h post-exposure. No effect on inhibin B (indicator of Sertoli cell function) production was observed at 96 h after cisplatin (0.5 and 1.0 μg/ml) exposure compared to control (21 ± 5 (0.5 μg/ml cisplatin) vs. 23 ± 7 (1.0 μg/ml cisplatin) vs. 25 ± 7 (control) ng/ml, p > 0.05). Xenografting of cisplatin-exposed (0.5 μg/ml) human fetal testicular tissues had no long-term effect on Sertoli cell number or function (percentage seminiferous area stained for SOX9 and AMH, respectively), compared with non-exposed tissues. Sertoli cell number was maintained in human pre-pubertal testicular tissues following exposure to either 0.5 μg/ml cisplatin (6,723 ± 1,647 cells/mm2) or 5 μg/ml carboplatin (7,502 ± 627 cells/mm2) compared to control (6,592 ± 1,545 cells/mm2). Conclusions: This study demonstrates maintenance of Sertoli cell number and function in immature human testicular tissues exposed to platinum-based chemotherapeutic agents. The maintenance of a functional Sertoli cell environment following chemotherapy exposure suggests that fertility restoration by spermatogonial stem cell (SSC) transplant may be possible in boys facing platinum-based cancer treatment.

O-190 Comparison between effects of exposure to platinum-based chemotherapeutics (cisplatin and carboplatin) on Sertoli cell number and functions in immature human testicular tissues

Study question

Does exposure to either cisplatin or carboplatin have a damaging effect on the Sertoli cell population in the immature human testicular tissues?

Summary answer

Exposure to cisplatin or carboplatin did not appear to have a major effect on Sertoli cell number or function in the immature human testicular tissues

What is known already

Long-term survival rates for children with cancer are more than 80%. However, childhood cancer treatment may result in subsequent infertility. Cisplatin is one of the most commonly used drugs for childhood cancers. Carboplatin, a second generation platinum drug, is administered at 10-times the dose of cisplatin and is believed to be less gonadotoxic. In our recent publication we have shown that exposure to both cisplatin and carboplatin acutely reduce the germ cell number in immature human testicular tissues. However, it is not known how cisplatin and carboplatin affect Sertoli cell number and function.

Study design, size, duration

In-vitro culture of human fetal and pre-pubertal testicular tissues was utilised. Tissue pieces were cultured for 1-3 days prior to exposure to clinically-relevant doses of chemotherapeutics or vehicle control for 24hrs in two sets of experiments: 1) 0.5 or 1 μg/ml cisplatin and culture ended at 24 and 96hrs post-exposure (fetal only); 2) 0.5 μg/ml cisplatin or 5 ­μg/ml carboplatin until 72 (both fetal and pre-pubertal) and 240hrs post-­exposure (fetal only).

Participants/materials, setting, methods

Testicular tissue fragments from second trimester human fetal (14-22 gestational weeks; n = 3-6) or pre-pubertal patients (1-8years old; n = 5) were cultured in a ‘hanging drop’ system.Quantification of Sertoli cell number (cells per cord/tubular area (mm2)) was performed on sections stained for expression of SOX9. Culture medium was collected to measure levels (ng/ml) of Anti-Mullerian hormone (AMH) and Inhibin B using ELISA. Statistical analysis was performed using two-way ANOVA to account for inter-individual variation between fetuses/patients.

Main results and the role of chance

Quantification of positively stained Sertoli cells showed that exposure to both doses of cisplatin had no effect on Sertoli cell number at 24 and 96hrs post-exposure. No changes in AMH and inhibin B levels were observed at these time-points. Comparison between cisplatin- or carboplatin-exposed human fetal testicular tissues showed no difference in Sertoli cell numbers at either 72hrs or 240hrs post-exposure. No difference in Sertoli cell number was observed in pre-pubertal testicular tissues exposed to either cisplatin or carboplatin at 72hrs post-exposure.

Limitations, reasons for caution

Human fetal and pre-pubertal testis tissue is of limited availability, thus, sample sizes used in this study were relatively low. ‘Hanging drop’ culture might not recapitulate all in-vivo aspects of immature testis microenvironment.

Wider implications of the findings

Exposure to cisplatin or carboplatin did not affect Sertoli cell number in the immature human testicular tissues. Taken together with our recent publication, this suggests that these two platinum-based chemotherapeutic agents cause direct damage to germ cells. Functionality of Sertoli cells in chemotherapy-exposed tissues need to be further investigated.

Trial registration number

not applicable

Cisplatin and carboplatin result in similar gonadotoxicity in immature human testis with implications for fertility preservation in childhood cancer

BACKGROUND

Clinical studies indicate chemotherapy agents used in childhood cancer treatment regimens may impact future fertility. However, effects of individual agents on prepubertal human testis, necessary to identify later risk, have not been determined. The study aimed to investigate the impact of cisplatin, commonly used in childhood cancer, on immature (foetal and prepubertal) human testicular tissues. Comparison was made with carboplatin, which is used as an alternative to cisplatin in order to reduce toxicity in healthy tissues.

METHODS

We developed an organotypic culture system combined with xenografting to determine the effect of clinically-relevant exposure to platinum-based chemotherapeutics on human testis. Human foetal and prepubertal testicular tissues were cultured and exposed to cisplatin, carboplatin or vehicle for 24 h, followed by 24-240 h in culture or long-term xenografting. Survival, proliferation and apoptosis of prepubertal germ stem cell populations (gonocytes and spermatogonia), critical for sperm production in adulthood, were quantified.

RESULTS

Cisplatin exposure resulted in a significant reduction in the total number of germ cells (- 44%, p < 0.0001) in human foetal testis, which involved an initial loss of gonocytes followed by a significant reduction in spermatogonia. This coincided with a reduction (- 70%, p < 0.05) in germ cell proliferation. Cisplatin exposure resulted in similar effects on total germ cell number (including spermatogonial stem cells) in prepubertal human testicular tissues, demonstrating direct relevance to childhood cancer patients. Xenografting of cisplatin-exposed human foetal testicular tissue demonstrated that germ cell loss (- 42%, p < 0.01) persisted at 12 weeks. Comparison between exposures to human-relevant concentrations of cisplatin and carboplatin revealed a very similar degree of germ cell loss at 240 h post-exposure.

CONCLUSIONS

This is the first demonstration of direct effects of chemotherapy exposure on germ cell populations in human foetal and prepubertal testis, demonstrating platinum-induced loss of all germ cell populations, and similar effects of cisplatin or carboplatin. Furthermore, these experimental approaches can be used to determine the effects of established and novel cancer therapies on the developing testis that will inform fertility counselling and development of strategies to preserve fertility in children with cancer.

The Dynamic Transcriptional Cell Atlas of Testis Development during Human Puberty

The human testis undergoes dramatic developmental and structural changes during puberty, including proliferation and maturation of somatic niche cells, and the onset of spermatogenesis. To characterize this understudied process, we profiled and analyzed single-cell transcriptomes of ∼10,000 testicular cells from four boys spanning puberty and compared them to those of infants and adults. During puberty, undifferentiated spermatogonia sequentially expand and differentiate prior to the initiation of gametogenesis. Notably, we identify a common pre-pubertal progenitor for Leydig and myoid cells and delineate candidate factors controlling pubertal differentiation. Furthermore, pre-pubertal Sertoli cells exhibit two distinct transcriptional states differing in metabolic profiles before converging to an alternative single mature population during puberty. Roles for testosterone in Sertoli cell maturation, antimicrobial peptide secretion, and spermatogonial differentiation are further highlighted through single-cell analysis of testosterone-suppressed transfemale testes. Taken together, our transcriptional atlas of the developing human testis provides multiple insights into developmental changes and key factors accompanying male puberty.

Effects of environmental Bisphenol A exposures on germ cell development and Leydig cell function in the human fetal testis

BACKGROUND

Using an organotypic culture system termed human Fetal Testis Assay (hFeTA) we previously showed that 0.01 μM BPA decreases basal, but not LH-stimulated, testosterone secreted by the first trimester human fetal testis. The present study was conducted to determine the potential for a long-term antiandrogenic effect of BPA using a xenograft model, and also to study the effect of BPA on germ cell development using both the hFETA and xenograft models.

METHODS

Using the hFeTA system, first trimester testes were cultured for 3 days with 0.01 to 10 μM BPA. For xenografts, adult castrate male nude mice were injected with hCG and grafted with first trimester testes. Host mice received 10 μM BPA (~ 500 μg/kg/day) in their drinking water for 5 weeks. Plasma levels of total and unconjugated BPA were 0.10 μM and 0.038 μM respectively. Mice grafted with second trimester testes received 0.5 and 50 μg/kg/day BPA by oral gavage for 5 weeks.

RESULTS

With first trimester human testes, using the hFeTA model, 10 μM BPA increased germ cell apoptosis. In xenografts, germ cell density was also reduced by BPA exposure. Importantly, BPA exposure significantly decreased the percentage of germ cells expressing the pluripotency marker AP-2γ, whilst the percentage of those expressing the pre-spermatogonial marker MAGE-A4 significantly increased. BPA exposure did not affect hCG-stimulated androgen production in first and second trimester xenografts as evaluated by both plasma testosterone level and seminal vesicle weight in host mice.

CONCLUSIONS

Exposure to BPA at environmentally relevant concentrations impairs germ cell development in first trimester human fetal testis, whilst gonadotrophin-stimulated testosterone production was unaffected in both first and second trimester testis. Studies using first trimester human fetal testis demonstrate the complementarity of the FeTA and xenograft models for determining the respective short-term and long term effects of environmental exposures.