Induction of differentiation by down-regulation of Nanog and Rex-1 in cord blood derived unrestricted somatic stem cells.

Stem cells with high self-renewal and tissue regeneration potentials are the core components of regenerative medicine. Adult stem cells with many available sources, high repairing ability, and also possessing no ethical issues are popular candidates in the clinical field. In this study we looked upon the effects of two transcription factors Nanog and Rex-1 in self-renewal and differentiation abilities of a subpopulation of cord blood stem cells known as unrestricted somatic stem cells (USSCs). USSCs were expanded and transfected in vitro with siRNAs targeting either Nanog, Rex-1, and in combination. Gene suppressions were achieved at both transcript and proteome level. Differentiations were evaluated by specific Real time PCR and differentiating staining. Nanog knock down revealed a significant increase in osteogenic markers, Osteocalcin and Osteopontin expression as well as a positive Alizarin Red staining, which proposes Osteogenesis. This treatment also became positive for Oil Red staining, implying adipogenic differentiation as well. In contrast, Rex-1 knock down showed an increase in MAP II and Nestin expression, which is a hall mark of neural differentiation. Surprisingly, treatment with both siRNAs did not express any changes in any of the assessed markers. Therefore, our results indicated a bilateral mesenchymal differentiation for Nanog and a neural lineage fate for Rex-1 suppression. Considering that both transcription factors are core activators of self-renewal and also are orchestrating with other factors, our results imply a positive feedback in response to changes in the regulatory network of self-renewal.