title: Xenografting of human fetal testis tissue: a new approach to study fetal testis development and germ cell differentiation.
abstract: BACKGROUND
  Abnormal fetal testis development can result in disorders of sex development (DSDs) and predispose to later testicular dysgenesis syndrome (TDS) disorders such as testicular germ cell tumours. Studies of human fetal testis development are hampered by the lack of appropriate model, and intervention systems. We hypothesized that human fetal testis xenografts can recapitulate normal development.
  
  
  METHODS
  Human fetal testes (at 9 weeks, n = 4 and 14-18 weeks gestation, n = 6) were xenografted into male nude mice for 6 weeks, with or without hCG treatment of the host, and evaluated for normal cellular development and function using immunohistochemistry, triple immunofluorescence and testosterone assay. The differentiation and proliferation status of germ cells within xenografts was quantified and compared with age-matched controls.
  
  
  RESULTS
  Xenografts showed >75% survival with normal morphology. In the first-trimester xenografts seminiferous cord formation was initiated and in first- and second-trimester grafts normal functional development of Sertoli, Leydig and peritubular myoid cells was demonstrated using cell-specific protein markers. Grafts produced testosterone when hosts were treated with hCG (P = 0.004 versus control). Proliferation of germ cells and differentiation from gonocytes (OCT4(+)) into pre-spermatogonia (VASA(+)) occurred in grafts and quantification showed this progressed comparably with age-matched ungrafted controls.
  
  
  CONCLUSIONS
  Human fetal testis tissue xenografts demonstrate normal structure, function and development after xenografting, including normal germ cell differentiation. This provides an in vivo system to study normal human fetal testis development and its susceptibility to disruption by exogenous factors (e.g. environmental chemicals). This should provide mechanistic insight into the fetal origins of DSDs and TDS disorders.
authors.affiliation: MRC Human Reproductive Sciences Unit, Centre for Reproductive Biology, The Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
authors.forename: Rod T
authors.initials: RT
authors.lastname: Mitchell
authors.forename: Philippa T K
authors.initials: PT
authors.lastname: Saunders
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Childs
authors.forename: Claire
authors.initials: C
authors.lastname: Cassidy-Kojima
authors.forename: Richard A
authors.initials: RA
authors.lastname: Anderson
authors.forename: W Hamish B
authors.initials: WH
authors.lastname: Wallace
authors.forename: Chris J H
authors.initials: CJ
authors.lastname: Kelnar
authors.forename: Richard M
authors.initials: RM
authors.lastname: Sharpe
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000008:administration & dosage; D006801:Humans; D007985:Leydig Cells / Q000166:cytology / Q000378:metabolism; D008297:Male; D051379:Mice; D008819:Mice, Nude; D050814:Octamer Transcription Factor-3 / Q000032:analysis; D012670:Seminiferous Epithelium / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism; D013091:Spermatogenesis; D013094:Spermatozoa / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D013737:Testis / Q000196:embryology* / Q000637:transplantation*; D013739:Testosterone / Q000096:biosynthesis; D014183:Transplantation, Heterologous
chemical_list: D006063:Chorionic Gonadotropin; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D013739:Testosterone