Complete spermatogenesis in intratesticular testis tissue xenotransplants from immature non-human primate

Abstract

STUDY QUESTION Can full spermatogenesis be achieved after xenotransplantation of prepubertal primate testis tissue to the mouse, in testis or subcutaneously? SUMMARY ANSWER Intratesticular xenotransplantation supported the differentiation of immature germ cells from marmoset ( Callithrix jacchus ) into spermatids and spermatozoa at 4 and 9 months post-transplantation, while in subcutaneous transplants, spermatogenic arrest was observed at 4 months and none of the transplants survived at 9 months. WHAT IS KNOWN ALREADY Auto-transplantation of cryopreserved immature testis tissue (ITT) could be a potential fertility restoration strategy for patients with complete loss of germ cells due to chemo- and/or radiotherapy at a young age. Before ITT transplantation can be used for clinical application, it is a prerequisite to demonstrate the feasibility of the technique and identify the conditions required for establishing spermatogenesis in primate ITT transplants. Although xenotransplantation of ITT from several species has resulted in complete spermatogenesis, in human and marmoset, ITT has not been successful. STUDY DESIGN, SIZE, DURATION In this study, we used marmoset as a pre-clinical animal model. ITT was obtained from two 6-month-old co-twin marmosets. A total of 147 testis tissue pieces (~0.8–1.0 mm 3 each) were transplanted into the testicular parenchyma (intratesticular; n = 40) or under the dorsal skin (ectopic; n = 107) of 4-week-old immunodeficient Swiss Nu/Nu mice ( n = 20). Each mouse received one single marmoset testis tissue piece in each testis and 4–6 pieces subcutaneously. Xenotransplants were retrieved at 4 and 9 months post-transplantation and evaluations were performed with regards to transplant survival, spermatogonial quantity and germ cell differentiation. PARTICIPANTS/MATERIALS, SETTING, METHODS Transplant survival was histologically evaluated by haematoxylin-periodic acid Schiff (H/PAS) staining. Spermatogonia were identified by MAGE-A4 via immunohistochemistry. Germ cell differentiation was assessed by morphological identification of different germ cell types on H/PAS stained sections. Meiotically active germ cells were identified by BOLL expression. CREM immunohistochemistry was performed to confirm the presence of post-meiotic germ cells and ACROSIN was used to determine the presence of round, elongating and elongated spermatids. MAIN RESULTS AND THE ROLE OF CHANCE Four months post-transplantation, 50% of the intratesticular transplants and 21% of the ectopic transplants were recovered ( P = 0.019). The number of spermatogonia per tubule did not show any variation. In 33% of the recovered intratesticular transplants, complete spermatogenesis was establis...

Validation of ultrasound biomicroscopy for the assessment of xenogeneic testis tissue grafts and cell implants in recipient mice

“…5 Using testis tissue xenografting models, it has been proposed that limited central vascularization combined with high oxygen and metabolic demands of the implanted cells during re-organization may lead to better development of testicular cords in the peripheral regions of the grafts. 5,38 In our study, only cell implants showed the differential pattern of cordal development, whereas all grafts displayed a uniform distribution of cords. However, in a study using young chicks, auto-transplanted testis tissue grafts maintained tubular structures in peripheral areas and their central areas undergoing necrosis.…”

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

“…xenotransplantation models. 39 Reports on possible DNA damage and impaired imprinting due to methylation changes might represent risks to the offspring. Three boys in our study had cryopreserved mature spermatozoa obtained from the testicular biopsies in two and from sperm aspiration in one.…”

FERTILITY PRESERVATION: Testicular transplantation for fertility preservation: clinical potential and current challenges

“…Therefore, strategies for generating functional sperm in autologous transplants would be preferable. This has been demonstrated in non-human primate models including rhesus monkey (Jahnukainen et al 2012) and marmoset (Luetjens et al 2008, Ntemou et al 2019, which also highlight the importance of the grafting site. For marmoset transplants, spermatogenesis occurred in orthotopic (intratesticular) tissues, but did not occur in tissues grafted ectopically (subcutaneous).…”