Xenografting of sheep testis tissue and isolated cells as a model for preservation of genetic material from endangered ungulates

Abstract

Recovery of germ cells could be an option for preservation of the genetic pool of endangered animals. In immature males, xenografting of testis tissue provides the opportunity to recover sperm from these animals. In adult animals, xenografting has been less successful, but de novo morphogenesis of functional testis tissue from dissociated testis cells could be an alternative. To assess the potential use of these techniques in endangered bovid species, the domestic sheep was used as a model. Testes from 2-week-old lambs were grafted as tissue fragments or cell suspensions into nude mice. Grafts were recovered at 4, 8, 12 and 16 weeks post grafting. For isolated cells, two additional time points at 35 and 40 weeks after grafting were added. In addition, to analyse the possible effect of social stress among mice within a group on the development of the grafts, testis tissue grafts were recovered 13 weeks post grafting from mice housed individually and in groups. Complete spermatogenesis occurred in sheep testis xenografts at 12 weeks, similar to the situation in situ. Isolated sheep testis cells were able to reorganize and form functional testicular tissue de novo. Housing mice individually or in groups did not have any effect on the development of xenografts. Xenografting of testis tissue might be useful to obtain sperm from immature endangered ungulates that die prematurely. Testis tissue de novo morphogenesis from isolated cells could open interesting options to recover germ cells from mature males with impaired spermatogenesis. Reproduction (2008) 136 85-93

Development of strips of ovine testes after xenografting under the skin of mice and co-transplantation of exogenous spermatogonia with grafts

“…The flat strips of testis from prepubertal ram lambs in this study survived engraftment and developed similarly to that reported for 1 mm 3 pieces from newborn lambs , Arregui et al 2008. Both in this study and that of Arregui et al (2008), grafts were collected up to 16 weeks after transplantation, and percentage of grafts that were recovered was 97 and 96% respectively.…”

“…The flat strips of testis from prepubertal ram lambs in this study survived engraftment and developed similarly to that reported for 1 mm 3 pieces from newborn lambs , Arregui et al 2008. Both in this study and that of Arregui et al (2008), grafts were collected up to 16 weeks after transplantation, and percentage of grafts that were recovered was 97 and 96% respectively. In this study, elongated spermatids were not detected at 8 weeks, but were detected at 16 weeks in 16% of tubules, while in the Arregui et al (2008) study they were not detected at 8 weeks and were present at 16 weeks in 19% of tubules.…”

“…Both in this study and that of Arregui et al (2008), grafts were collected up to 16 weeks after transplantation, and percentage of grafts that were recovered was 97 and 96% respectively. In this study, elongated spermatids were not detected at 8 weeks, but were detected at 16 weeks in 16% of tubules, while in the Arregui et al (2008) study they were not detected at 8 weeks and were present at 16 weeks in 19% of tubules. Although small cube xenografts were not included in this study, the size of our strips (w45 mm 3 ) at xenografting is much bigger than the cubic pieces (w1 mm 3 ) used by Arregui et al (2008), and thus it is reasonable to expect that there will be more seminiferous tubules with complete spermatogenesis in each of the strip xenografts than in each small cube of tissue.…”

Optimal dose of busulfan for depleting testicular germ cells of recipient mice before spermatogonial transplantation

“…Studies of spermatogenesis were long hampered because of a lack of powerful in vitro and in vivo assay systems until an exciting new technique, a method for the transplantation of germ cells from one animal to another, was established [1]. It was shown that germ cells from hamsters, rabbits, dogs, sheep or bulls can be heterotransplanted into the mouse, which then survive and result in long-lasting spermatogenesis in the host testes, proliferate and differentiate into spermatozoa or elongated spermatids [2][3][4][5]. Germ-cell transplantation has also been successfully performed in cat, goat, pig, monkey and human testes [6][7][8][9].…”

Cryopreservation of Testicular Tissue

“…The approach has especially been successful using neonatal/immature donors (Fig. 5), from laboratory animals to domestic animals, primates, and even humans (Honaramooz et al, 2002aSchlatt et al, 2002;Oatley et al, 2004;Snedaker et al, 2004;Rathi et al, 2005Rathi et al, , 2006Arregui et al, 2008;Abrishami et al, 2010b). .…”