title: Glial cell line-derived neurotrophic factor and endothelial cells promote self-renewal of rabbit germ cells with spermatogonial stem cell properties.
abstract: Previous studies suggest that exogenous factors crucial for spermatogonial stem cell (SSC) self-renewal are conserved among several mammalian species. Since glial cell line-derived neurotrophic factor (GDNF) and fibroblast growth factor 2 (FGF2) are critical for rodent SSC self-renewal, we hypothesized that they might promote self-renewal of nonrodent SSCs. Therefore, we cultured testicular germ cells from prepubertal rabbits in the presence of GDNF and FGF2 and found they proliferated indefinitely as cellular clumps that displayed characteristics previously identified for rodent SSCs. The rabbit germ cells could not be maintained on mouse embryonic fibroblast (STO) feeders that support rodent SSC self-renewal in vitro but were rather supported on mouse yolk sac-derived endothelial cell (C166) feeder layers. Proliferation of rabbit germ cells was dependent on GDNF. Of critical importance was that clump-forming rabbit germ cells colonized seminiferous tubules of immunodeficient mice, proliferated for at least 6 mo, while retaining an SSC phenotype in the testes of recipient mice, indicating that they were rabbit SSCs. This study demonstrates that GDNF is a mitogenic factor promoting self-renewal that is conserved between rodent and rabbit SSCs; with an evolutionary separation of ∼ 60 million years. These findings provide a foundation to study the mechanisms governing SSC self-renewal in nonrodent species.
authors.affiliation: Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, 3850 Baltimore Ave., Philadelphia, PA 19104, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kubota
authors.forename: Xin
authors.initials: X
authors.lastname: Wu
authors.forename: Shaun M
authors.initials: SM
authors.lastname: Goodyear
authors.forename: Mary R
authors.initials: MR
authors.lastname: Avarbock
authors.forename: Ralph L
authors.initials: RL
authors.lastname: Brinster
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000494:pharmacology*; D008297:Male; D051379:Mice; D011817:Rabbits; D013045:Species Specificity; D013091:Spermatogenesis / Q000187:drug effects; D013093:Spermatogonia / Q000166:cytology* / Q000187:drug effects* / Q000637:transplantation; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects*
chemical_list: D051100:Glial Cell Line-Derived Neurotrophic Factor; D016222:Fibroblast Growth Factor 2