Acute kidney injury (AKI) and chronic renal failure (CKD) are the most challenging problems in nephrology. Multiple and varied therapies have been attempted, but these interventions have minimal effects on the eventual outcomes, and all too often the result is end-stage renal disease (ESRD). The only effective therapy for ESRD is renal transplantation but only a small fraction of ESRD patients receive transplants. In this work we introduce a novel approach to transplantation designed to regenerate kidneys afflicted by severe AKI or CKD. Intravenous renal cell transplantation (IRCT) with adult rat primary renal cells re-programmed to express the SAA gene localized and engrafted in kidneys of rat recipients that had severe AKI or CKD. IRCT significantly resolved renal dysfunction and limited kidney damage, inflammation and fibrosis. Severe CKD was successfully improved by IRCT using kidney cells from donor rats or by renal cell self-donation in a form of auto-transplantation. We propose that IRCT with adult primary renal cells re-programmed to express the SAA gene can be used to effectively treat AKI and CKD.