Experimental Approaches for Fertility Preservation in Prepubertal Boys Undergoing Oncological Therapy

Document Type : Review

Author

1. Gametogenesis Research Center, Kashan University of Medical Sciences, Kashan, Iran.

Abstract

An increasing number of prepubertal boys encountering infertility due to cancer treatment has prompted a range of studies to set up new methods for fertility restoration and male germ cell maturation. In this regard, cryopreservation of immature testicular tissue (ITT) from biopsy samples is being progressively advised in infertility centers. Different strategies to in vivo or in vitro male germ cell development using stored testicular tissues have been followed: autotransplantation or Xenotransplantation of testicular tissue pieces, spermatogonial stem cells (SSCs) isolation, and transplantation, in vitro spermatogenesis using three-dimensional (3D) culture and tissue culture. Combination of these strategies with assisted reproductive techniques (ART) like intracytoplasmic sperm injection (ICSI) and in vitro fertilization (IVF) has resulted from complete spermatogenesis resulting in offspring in several animal models but no achievement in producing mature spermatozoa from human prepubertal SSCs has yet been reported. This review describes studies done by researcher making effort on fertility restoration from ITT containing SSCs, Considering the limitations and specific concerns of each strategy.

Highlights

  • An increasing number of prepubertal boys encountering infertility due to cancer treatment.
  • Cryopreservation of immature testicular tissue (ITT) is being advised in infertility centres.
  • This review describes studies done by researcher making effort on fertility restoration.

Keywords

Main Subjects


Introduction

Although oncological therapy has resulted in significant improvements in life satisfaction of prepubertal boys with cancer, it has adverse effects on their gonads such as azoospermia and decreased fertility potential, when they become adults (1). Sperm banking is a reliable option for postpubertal adolescents and young men but cryopreservation of ITT is the only solution for prepubertal boys (2). Alternative methods for fertility protection for these younger patients are still at the research level and do not apply to the clinic. At the present, to achieve these goals, two main experimental protocols have been addressed by the researcher: 1) testicular germ cell transplantation or testicular grafting into host animals (3-5) or 2) germ cell or testicular tissue culture(6, 7), as shown in Figure 1.

 

 

Figure 1. Experimental protocols for fertility protection in prepubertal boys with cancer and their possible clinical applications (8). Isolation and in-vitro proliferation and transplantation of SSCs. In-vitro spermatogenesis using 3D or conventional culture systems. III. Ex vivo testicular tissue culture. IV. Xenografting of cryopreserved tissue under the skin of immunodeficient mice

 

 Xenotransplantation of ITTs or SSCs

 Xenotransplantation provides a microenvironment by maintaining molecular interactions and a testicular compartment for spermatogonial stem cells (SSCs) similar to the situation in the donor. Although grafting efficiency is low, tissue maturation and complete spermatogenesis have been achieved in ITT grafted under the skin of immunodeficient mice in several animal species (3, 4, 9) and also the resumption of spermatogenesis in slow-frozen ITT xenografts from rabbits (10), pigs (3), lambs (11) and primates (12) has been reported with lower efficiency than fresh tissue. Despite the advances in animal studios, the study in which spermatogenesis became complete using xenotransplantation of human ITT has not yet been published (13). xenotransplantation is a useful option to study the potential of ITT grafts but its disadvantages such as animal contamination, hypoxia of grafted tissues, the endocrine difference between donor and recipient should be addressed and improved in future studies (1). Transplantation of testicular cell suspension to the testes of infertile mice was the first study for the SSC transplantation approach instead of xenotransplantation of human ITT, yielding offspring (5). This method was used for other species, such as non-human primates (14) and it has led to spermatozoa generation or offspring. Excluding cancer cells from testicular cell suspensions and using specific culture conditions for the suitable proliferation of SSCs are several concerns that still need to be considered before clinical use (1).

 

In vitro maturation of ITTs or SSCs

For the elimination of concerns related to autologous SSC transplantation or ITT grafting, cited above, in vitro spermatogenesis using a 3D cell culture system or tissue culture can be an alternative method (6). Fertile sperm obtained in vitro organotypic culture of fresh mice ITTs led to offspring (7). This study has opened a new window for understanding the developmental requirements of in vitro maturation of sperm such as cellular interaction, special arrangement, and paracrine communication (6). Concerning the importance of cell-cell contacts, conventional cultures were replaced with 3D culture systems providing a spatial arrangement in which the testicular cells can have interaction and communication (15). In 3D culture, testicular cell suspensions are embedded in collagen (15), alginate, or agar matrix (6, 16) to provide the microenvironment which regulates germ cell maturation and cellular interactions. Stukenborg et al. reported a study in which the entire spermatogenic process occurred in vitro after embedding mouse testicular cells in a soft agar culture system (6).

 

Conclusions

Taking everything into account, cryopreservation of ITT before oncological therapy has now been accepted for more than a decade by infertility centers worldwide, and today, ITT banks have put much pressure on researchers and clinicians to respond to Patients' expectations hoping fertility restoration. All methods cited in this review for SSC maturation in vivo or in vitro led to complete spermatogenesis sperm or offspring in at least one animal model. With the knowledge of limitations like complex human spermatogenic process, the scarcity of human ITT, more efforts should be done for fertility protection in prepubertal boys with cancer.

 

Acknowledgments

Special thanks to the Kashan University of Medical Sciences.

 

Conflict of interest

The author declares that there are no conflicts of interest.

 

Funding

No Funding.

 

Ethical statements

Not applicable

 

Data availability

Not applicable

 

Abbreviations

ART     Assisted reproductive techniques

ICS       Intra Cytoplasmic Sperm Injection

ITT       Immature testicular tissue

IVF       In-vitro Fertilization

SSCs   Spermatogonial stem cells

3D        Three-dimensional

1.            Giudice MG, De Michele F, Poels J, Vermeulen M, Wyns CJScr. Update on fertility restoration from prepubertal spermatogonial stem cells: how far are we from clinical practice? 2017;21:171-7.
2.            Wyns C, Curaba M, Vanabelle B, Van Langendonckt A, Donnez JJHru. Options for fertility preservation in prepubertal boys. 2010;16(3):312-28.
3.            Honaramooz A, Snedaker A, Boiani M, Schöler H, Dobrinski I, Schlatt SJN. Sperm from neonatal mammalian testes grafted in mice. 2002;418(6899):778-81.
4.            Nakai M, Kaneko H, Somfai T, Maedomari N, Ozawa M, Noguchi J, et al. Production of viable piglets for the first time using sperm derived from ectopic testicular xenografts. 2010;139(2):331.
5.            Brinster RL, Zimmermann JWJPotNAoS. Spermatogenesis following male germ-cell transplantation. 1994;91(24):11298-302.
6.            Stukenborg J-B, Schlatt S, Simoni M, Yeung C-H, Elhija MA, Luetjens CM, et al. New horizons for in vitro spermatogenesis? An update on novel three-dimensional culture systems as tools for meiotic and post-meiotic differentiation of testicular germ cells. 2009;15(9):521-9.
7.            Sato T, Katagiri K, Gohbara A, Inoue K, Ogonuki N, Ogura A, et al. In vitro production of functional sperm in cultured neonatal mouse testes. 2011;471(7339):504.
8.            Zarandi NP, Galdon G, Kogan S, Atala A, Sadri-Ardekani HJSc, advances c, et al. Cryostorage of immature and mature human testis tissue to preserve spermatogonial stem cells (SSCs): A systematic review of current experiences toward clinical applications. 2018;11:23.
9.            Schlatt S, Kim SS, Gosden RJR-C-. Spermatogenesis and steroidogenesis in mouse, hamster and monkey testicular tissue after cryopreservation and heterotopic grafting to castrated hosts. 2002;124(3):339-46.
10.          Shinohara T, Inoue K, Ogonuki N, Kanatsu-Shinohara M, Miki H, Nakata K, et al. Birth of offspring following transplantation of cryopreserved immature testicular pieces and in-vitro microinsemination. 2002;17(12):3039-45.
11.          Pukazhenthi BS, Nagashima J, Travis AJ, Costa GM, Escobar EN, França LR, et al. Slow freezing, but not vitrification supports complete spermatogenesis in cryopreserved, neonatal sheep testicular xenografts. 2015;10(4):e0123957.
12.          Jahnukainen K, Ehmcke J, Nurmio M, Schlatt SJCr. Autologous ectopic grafting of cryopreserved testicular tissue preserves the fertility of prepubescent monkeys that receive sterilizing cytotoxic therapy. 2012;72(20):5174-8.
13.          Wyns C, Van Langendonckt A, Wese F-X, Donnez J, Curaba MJHr. Long-term spermatogonial survival in cryopreserved and xenografted immature human testicular tissue. 2008;23(11):2402-14.
14.          Honaramooz A, Behboodi E, Megee SO, Overton SA, Galantino-Homer H, Echelard Y, et al. Fertility and germline transmission of donor haplotype following germ cell transplantation in immunocompetent goats. 2003;69(4):1260-4.
15.          Lee J-H, Gye MC, Choi KW, Hong JY, Lee YB, Park D-W, et al. In vitro differentiation of germ cells from nonobstructive azoospermic patients using three-dimensional culture in a collagen gel matrix. 2007;87(4):824-33.
16.          Gholami K, Pourmand G, Koruji M, Sadighigilani M, Navid S, Izadyar F, et al. Efficiency of colony formation and differentiation of human spermatogenic cells in two different culture systems. 2018;18(4):397-403.