Differentiation of Testis Xenografts in the Prepubertal Marmoset Depends on the Sex and Status of the Mouse Host.

Swati Sharma,Stefan Schlatt,Reinhild Sandhowe-Klaverkamp

doi:10.3389/fendo.2018.00467

Abstract

This study investigates the effects of the endocrine milieu of immunodeficient mouse host (intact vs. castrated male, intact male vs. intact female) on prepubertal marmoset (Callithrix jacchus) testicular xenografts. Previous marmoset xenografting studies used castrated nude mouse hosts which did not support efficient graft survival and maturation. Due to the distinct endocrine milieu in marmosets with a deletion of exon 10 in the LH receptor, we wanted to explore whether the most efficient xenograft development occurs in intact male mouse hosts compared to intact females or castrated males. We xenografted freshly isolated tissue from prepubertal marmosets (age range 4–6 months) into the back skin of three groups of nude mice (intact male, castrated male, and intact female). We collected serum for endocrine determinations and grafts after 20 weeks and determined hormonal/reproductive status, graft survival, somatic cell development and initiation of germ cell differentiation. Graft development, tubular integrity, and germ cell differentiation status in the grafts retrieved from different hosts was scored by morphometric analysis. The influence of the different endocrine status was compared between groups of hosts. Endocrine readouts and histological endpoints in xenografts substantiate that grafts were exposed to different microenvironments and responded with host specific developmental patterns. The intact male hosts supported the most significant progression of germ cell development. Our data provide evidence for the important role of the host milieu on survival and differentiation of marmoset xenografts. The xenografting model offers innovative avenues to exploit development and endocrine effects in the primate marmoset testis using limited numbers of non-human primates for the experimental settings.

Highlights

Xenografting of testicular tissue can be considered co-transplantation of germ cells with its somatic microenvironment into a host
One hundred and twenty testicular fragments were xenografted. 71 of 120 grafts were retrieved in total and subjected to histological evaluation revealing that 32 of 71 grafts contained seminiferous tubules
The xenografting model has been previously used [1, 16]. It is a central strategy in the present study and served as a valid and innovative translational research approach since it allowed the use of limited primate testicular material to generate valid and functional outcomes on spermatogenic induction and testicular development

Summary

Introduction

Xenografting of testicular tissue can be considered co-transplantation of germ cells with its somatic microenvironment into a host. Host Effect in Testis Xenografting experimental tool to generate sperm from testicular fragments of various species (mouse, pig, goat, sheep, hamster, bull, rhesus monkey) [1, 3,4,5,6,7,8,9]. The study gains relevance from the fact that ectopic xenografting of human prepubertal testicular tissue is currently being developed as a clinically viable fertility preservation strategy. Experimental exploration using non-human primates revealed the generation of functional sperm in ectopically grafted macaque testicular xenografts [1, 5, 8, 9, 16,17,18]. Past marmoset and human xenografting studies investigated the effect of donor tissue (maturation status), effect of gonadotropins as well as time post grafting and site of grafting on xenograft survival and maturation [1, 12, 16, 19,20,21,22]

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