Contribution of intrarenal cells to cellular repair after acute kidney injury: subcapsular implantation technique

The kidney is capable of regeneration following injury, particularly following acute insults. Although the mechanisms underlying cellular regeneration are incompletely understood, emerging evidence suggests a role for cells of renal origin in the repair and replacement of damaged renal tubule cells. The overall hypothesis of this study is that native kidney cells that reside in a niche in the kidney provide robust contribution to the repair of kidney tubules following injury. To test this hypothesis, we utilized a model of renal ischemia-reperfusion injury that results in extensive morphological changes, particularly in the outer medulla. Renal tissue obtained from mice constitutively expressing Escherichia coli [beta]-galactosidase (ROSA26) was dissected from the cortex, outer medulla, or papilla and implanted under the renal capsule of the injured mice. Mice were allowed to recover for 7 days. Sections through the injured kidney demonstrated the presence of implantderived cells in renal tubules in the outer medulla. The implanted renal region that exhibited the most robust response was the papilla, whereas tissue pieces from the cortex and outer medulla showed less contribution to recipient renal tubules. These results provide proofof-principle evidence that renal-derived reparative cells reside in all regions of the kidney, perhaps more predominantly in the renal papilla. A greater understanding of the cell biology of renal repair by native kidney cells will provide further insight into the design of novel therapies in acute kidney injury, and the subcapsular implant technique described in this study may offer unique advantages to evaluate renal repair mechanisms. epithelial repair; ischemia-reperfusion injury; progenitor cells