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

Abstract

STUDY QUESTIONDoes chemotherapy exposure (with or without alkylating agents) or primary diagnosis affect spermatogonial quantity in human prepubertal testicular tissue?SUMMARY ANSWERSpermatogonial quantity is significantly reduced in testes of prepubertal boys treated with alkylating agent therapies or with hydroxyurea for sickle cell disease.WHAT IS KNOWN ALREADYCryopreservation 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, DURATIONWe 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, METHODSPrepubertal 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 CHANCEThe 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 te...

Hypogonadism in Children with a Previous History of Cancer: Endocrine Management and Follow-Up

“…Several research groups are exploring the possibility that cryopreservation of prepubertal testicular tissue with a view to subsequent spermatogonial stem cell transplantation may preserve future fertility [41, 42]. In some animal models, this has been successful; in humans, this must still be considered experimental [43, 44]. …”

Development and Disease-Dependent Dynamics of Spermatogonial Subpopulations in Human Testicular Tissues

“…Due to limited access to healthy pre/pubertal testicular tissue, in our study, the spermatogonial expression patterns during testicular development were established for untreated cancer patients without any preexisting (congenital) risk factors for impaired testicular function. Reassuringly, Stukenborg et al and Valli-Pulaski et al recently reported that spermatogonial numbers per tubular cross section of untreated cancer patients were within the confidence interval of spermatogonial reference values previously established in healthy boys [10,15,21].…”

“…Reasons for this include pathological conditions such as cryptorchidism and genetic or endocrine disorders [1][2][3][4][5]. Apart from that, cancer therapy and conditioning treatments of non-malignant diseases such as sickle cell disease and thalassemia, are known to induce testicular damage, affect spermatogonial function and reduce or even deplete germ cells [4][5][6][7][8][9][10]. Consequently, gonadotoxic treatment may lead to temporary or permanent infertility depending on treatment dose and duration, patients' age and underlying diagnosis [11][12][13].…”

“…Descriptive and qualitative information of the heterogeneous prepubertal testicular tissues is pivotal to determine its potential use in fertility restoration strategies. While accumulating evidence on spermatogonial numbers in bio-banked tissues is reported, evaluation of molecular properties of spermatogonia remains limited [4,5,9,10,15].…”

Fertility sparing strategies for pre- and peripubertal male cancer patients

“…In vitro propagation of SSCs will most likely be required before transplantation due to the scarcity of SSCs in the testis. Treatment related decrease of spermatogonia quantity reported in cancer patients [24,25] as well as the poor colonisation efficiency of cell transplantation calculated in animal models [26,27], also need to be taken in consideration. However, while in vitro propagation of human prepubertal SSCs was reported [28], safety issues linked to potential cell modification in culture as well as the functional proof that these cells are able to reinitiate sperm production, still need to be addressed.…”