Derivation of sperm from xenografted testis cells and tissues of the peccary (Tayassu tajacu)

Abstract

Because the collared peccary (Tayassu tajacu) has a peculiar Leydig cell cytoarchitecture, this species represents a unique mammalian model for investigating testis function. Taking advantage of the well-established and very useful testis xenograft technique, in the present study, testis tissue and testis cell suspensions from immature collared peccaries (nZ4; 3 months old) were xenografted in SCID mice (nZ48) and evaluated at 2, 4, 6, and 8 months after grafting. Complete spermatogenesis was observed at 6 and 8 months after testis tissue xenografting. However, probably due to de novo testis morphogenesis and low androgen secretion, functionally evaluated by the seminal vesicle weight, a delay in spermatogenesis progression was observed in the testis cell suspension xenografts, with the production of fertile sperm only at 8 months after grafting. Importantly, demonstrating that the peculiar testicular cytoarchitecture of the collared peccary is intrinsically programmed, the unique Leydig cell arrangement observed in this species was re-established after de novo testis morphogenesis. The sperm collected from the xenografts resulted in diploid embryos that expressed the paternally imprinted gene NNAT after ICSI. The present study is the first to demonstrate complete spermatogenesis with the production of fertile sperm from testis cell suspension xenografts in a wild mammalian species. Therefore, due to its unique testicular cytoarchitecture, xenograft techniques, particularly testis cell suspensions, may represent a new and very promising approach to evaluate testis morphogenesis and to investigate spermatogonial stem cell physiology and niche in the collared peccary.

Slow Freezing, but Not Vitrification Supports Complete Spermatogenesis in Cryopreserved, Neonatal Sheep Testicular Xenografts

“…A basis for this justification comes from work in common, mostly domesticated species where testicular tissue is recovered within 24 h of death and the testicular parenchyma dissected into 1 to 2 mm 3 pieces that are placed immediately (or after cryopreservation/thawing) under the skin of special, immune-suppressed mice to initiate spermatogenesis in vivo [ 9 – 10 ]. Round spermatids, elongating spermatids or spermatozoa have been isolated from these xenografts and used with intracytoplasmic sperm injection (ICSI) to produce embryos or live offspring [ 9 – 11 ]. With fresh testicular tissue, this approach has been used to achieve complete or advanced stages of spermatogenesis in the domesticated goat [ 12 ], pig [ 12 ], rabbit [ 13 ], bull [ 14 , 15 ], cat [ 16 , 17 ], horse [ 18 ], sheep [ 19 , 20 ], dog [ 21 ], hamster [ 22 ], ferret, Mustela putorius [ 23 ] and the non-domesticated bison ( Bison bison bison [ 24 ], rhesus monkey [ 25 ], Javan banteng ( Bos javanicus javanicus [ 26 ], white-tailed deer ( Odocoileus virginianus [ 27 ]), Mohor gazelle ( Gazella dama mohor [ 28 ]) and collared peccary ( Tayassu tajacu [ 11 ]) as well as the human [ 29 ].…”

Spermatogonial stem cells: Current biotechnological advances in reproduction and regenerative medicine

“…Interestingly, all these cells reassemble under the mouse skin and testicular tissue becomes organized in a process that has been called de novo testicular morphogenesis [106,107] . This novel technique has been tested with testicular cell suspensions from rats [108] , mice [109] , pigs [110] , sheep [111] and recently from a wild pig, the peccary [112] . Testis xenografts have produced so far fertile sperm in pigs and the related peccaries [112][113][114] demonstrating that SSCs present in the testicular tissues show a correct functioning that leads to the production of viable normal sperm within the body of a foreign species.…”

Assisted Reproductive Techniques on South American Wild Mammals

“…Although this is a promising area, studies on the collection of sperm or even on the preservation of testicular tissues are very scarce. In South American individuals, the unique published results can be found in collared peccaries, in which the first successful xenotransplantation of fresh testicular tissue was also documented [42]. In addition, its testicular tissue was efficiently vitrified using ethylene glycol (EG) as cryoprotectant at 3.0 or 6.0 M [43].…”