Scalable control of stem cell fate by riboswitch-regulated RNA viral vector without genomic integration.

Transgene expression in stem cells is a powerful means of regulating cellular properties and differentiation into various cell types. However, existing vectors for transgene expression in stem cells suffer from limitations such as the need for genomic integration, the transient nature of gene expression, and the inability to temporally regulate transgene expression, which hinder biomedical and clinical applications. Here we report a new class of RNA virus-based vectors for scalable and integration-free transgene expression in mouse embryonic stem cells (mESCs). The vector is equipped with a small molecule-regulated riboswitch and a drug selection marker that allow temporal regulation of transgene expression and stable maintenance of the vector in proliferating stem cells. We demonstrated the utility of the vector by maintaining the pluripotency of mESCs in a differentiation induction medium by expressing Nanog and inducing myogenic differentiation by triggering Myod1 expression, without altering the mESC genome.