Investigation of Spermatogonial Stem Cells in Adherent and Non-Adherent Culture

Spermatogonial stem cells are the undifferentiated cells in the basal membrane of the seminiferous tubules and are able to produce sperm in male testis. Different experimental studies proved the capatility of undifferentiated spermatogonial stem cells to culture under different conditions, after isolation of the testes. In this study mouse neonate testicular cells (5-7 days-old NMRI strain) isolated by digestive enzymes include Collagenase IV, Dispase and DNAse. Then, approximately 106 cells were cultured in both adherent on MEF feeder layer and non-adherent culture system on 1% agarose with condition mediums that contained growth factors. Studies demonstrates that testicular cells cultured in a non-adherent condition (non-adherent colonies) were able to form colonies similar to spermatogonial stem cell colonies in adherent condition (adherent colonies) and clearly expressed germ cell marker. Electron microscope analyses made evident that both types of colonies were similar to localized spermatogonial stem cells on the basement membrane of seminiferous tubules and showed a high nucleus/cytoplasm ratio. Immunocytochemistry assays proved that both of colony expressed germ cell markers β1-Integrin, α6-Integrin and Oct4 positive. Real-time PCR analysis revealed significant differences in the expression of germ cell genes Oct4, Sox-2, CD9 and EPCAM, between these colonies and somatic cells. On the other hand, high expression of Ki67 in these colonies showed that these cells have proliferative characteristics. These results proved that a non-adherent culture system similar to adherent culture could provide a favorable method for in vitro short-term culture of spermatogonial stem-like cell colonies.