The present invention relates to a cellular therapy of renal failure, i.e. preventing, delaying, and treating acute/chronic renal failure via the use of an effective dose of a substance capable of inducing and/or enhancing Pax2 expression in a mammal for the preparation of a pharmaceutical composition for treating, preventing or delaying a renal dysfunction/failure in a mammal. Additionally, the present invention provides for a method for converting mesenchymal tissue into an epithelial tissue comprising the administration of an effective amount of a substance capable of inducing and/or enhancing Pax2 expression in mesenchymal tissue and for a method for the regeneration of renal stem cells comprising the administration of an effective amount of a substance capable of inducing and/or enhancing Pax2 expression.