Gene Expression Profiling of the SSC-Enriched Thy1+ and SSC-Depleted Thy1- Fractions of Prepubertal Mouse Testes

Self-renewal and differentiation of spermatogonial stem cells (SSCs) provides the foundation for testis homeostasis, yet mechanisms that control their functions in mammals are poorly defined. We used microarray transcript profiling to identify specific genes whose expression are augmented in the SSC-enriched Thy1+ germ cell fraction of mouse pup testes. Comparisons of gene expression in the Thy1+ germ cell fraction to the Thy1-depeleted testis cell population identified 202 genes that are expressed 10-fold or higher in Thy1+ cells. This database provided a mining tool to investigate specific characteristics of SSCs and identify novel mechanisms that potentially influence their functions. Testis cell fractions with different spermatogonial stem cell contents from mouse testes were collected using a modified MACS isolation. Three replicate samples were collected for each fraction from independent donor preparations. The stem cell contents of these cell fractions were determined using functional germ cell transplantation which showed a >25-fold enrichement of stem cells in the Thy1+ fration. Gene expression profiles were evaluated using DNA microarray analysis and genes expressed 10-fold or greater in the Thy1+ fraction compared to the Thy1- population were identified.