The invention relates to the alteration of cell properties using RNA molecules. In particular, it relates to the alteration of the ability of cells to mobilise, migrate, integrate, proliferate and/or differentiate. For example, it relates to the induction of differentiation of stem cells, including the acquisition of the ability to migrate, integrate, and proliferate. It also relates to the induction of in vivo stem cell mobilisation, migration, integration, proliferation and/or differentiation. Accordingly, it relates to the promotion of stem cell-mediated functional repair. The invention also relates to the reversal of differentiation of differentiated cells. All these effects may be effected by providing isolated RNA comprising a RNA sequence extractable from cells comprising the desired cell type(s) to a population of cells under conditions whereby the alteration of the cell property is achieved.