Phenotypic and molecular characterization of spermatogonial stem cells in adult primate testes.
BACKGROUND
Knowledge about the identity and characteristics of spermatogonial stem cells (SSCs) in human is very limited. Here, Rhesus monkey was used as an animal model to investigate molecular and phenotypic characteristics of SSCs in the adult testes.


METHODS
A variety of immunohistological, molecular biological and functional assays were used to study different populations of SSCs in the adult testes.


RESULTS
In adult primate testes, there are distinct populations of CD90+ CD49f+ CD117- (Triple Stained) cells and a small population of stage-specific embryonic antigen-4 (SSEA-4)+ cells which both localized at the basement membrane of seminiferous tubules. Both SSEA-4+ and Triple Stained cells express germ cell and SSC-specific markers and show high telomerase activity; however, only adult Rhesus monkey SSEA-4+ testis cells appear to contain functional and actively dividing SSCs that can repopulate recipient mouse testes following spermatogonial transplantation. DNA analysis of these populations showed that SSEA-4+ cells contain a DNA profile similar to the actively dividing cells, whereas Triple Stained cells showed an accumulated number of cells arrested in the S phase of the cell cycle. SSEA-4+ cells also showed significantly higher proliferation activity, as shown by proliferating cell nuclear antigen staining, than Triple Stained cells (P < 0.01). Interestingly, SSEA-4+ cells expressed a significantly higher level of promyelocytic leukemia zinc finger, a factor required for SSC self-renewal, than Triple Stained cells (P < 0.001).


CONCLUSIONS
Our data indicate that Triple Stained cells may represent a quiescent population of SSCs, whereas SSEA-4 might be expressed on a subpopulation of actively dividing SSCs.
Maki
Chad B
CB
PrimeGen Biotech, 213 Technology Drive, Irvine, CA 92618, USA.
Pacchiarotti
Jason
J
Ramos
Thomas
T
Pascual
Michael
M
Pham
Jane
J
Kinjo
Jessie
J
Anorve
Sandra
S
Izadyar
Fariborz
F
D000367:Age Factors; D000818:Animals; D015415:Biomarkers; D002455:Cell Division / Q000502:physiology; D005434:Flow Cytometry; D007150:Immunohistochemistry; D008253:Macaca mulatta; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D008819:Mice, Nude; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013093:Spermatogonia / Q000166:cytology* / Q000502:physiology*; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology*; D019098:Telomerase / Q000235:genetics / Q000378:metabolism; D013737:Testis / Q000166:cytology*; D014183:Transplantation, Heterologous
D015415:Biomarkers; D019098:Telomerase