The fate of bone marrow-derived cells carrying a polycystic kidney disease mutation in the genetically normal kidney

BACKGROUND: Polycystic Kidney Disease (PKD) is a genetic condition in which dedifferentiated and highly proliferative epithelial cells form renal cysts and is frequently treated by renal transplantation. Studies have reported that bone marrow-derived cells give rise to renal epithelial cells, particularly following renal injury as often occurs during transplantation. This raises the possibility that bone marrow-derived cells from a PKD-afflicted recipient could populate a transplanted kidney and express a disease phenotype. However, for reasons that are not clear the reoccurrence of PKD has not been reported in a genetically normal renal graft. We used a mouse model to examine whether PKD mutant bone marrow-derived cells are capable of expressing a disease phenotype in the kidney. METHODS: Wild type female mice were transplanted with bone marrow from male mice homozygous for a PKD-causing mutation and subjected to renal injury. Y chromosome positive, bone marrow-derived cells in the kidney were assessed for epithelial markers. RESULTS: Mutant bone marrow-derived cells were present in the kidney. Some mutant cells were within the bounds of the tubule or duct, but none demonstrated convincing evidence of an epithelial phenotype. CONCLUSIONS: Bone marrow-derived cells appear incapable of giving rise to genuine epithelial cells and this is the most likely reason cysts do not reoccur in kidneys transplanted into PKD patients.