Is the most important role of the bone marrow–derived cell protective rather than reparative in the kidney?
The study by Duffield et al. reported in this issue of the JCI (10) demonstrates the ability of purified MSCs to improve renal function in an I/R model of acute tubular injury in the mouse, but the authors noted an important difference from the prior studies. They found that the effects of transplanted MSCs were independent of any direct contribution to the renal parenchyma, either tubular or endothelial in nature. Furthermore, using 3 separate approaches for tracking donor-derived cells (GFP, Y chromosome, and β-gal), they found that animals undergoing whole bone marrow transplantation followed by acute renal injury also failed to exhibit any tubular cells derived from donor bone marrow, although they did find small numbers of cells expressing endothelial markers that were of bone marrow origin in the kidneys of these animals (Figure 1). The absence of bone marrow–derived endothelial cells in kidneys from mice transplanted with purified MSCs suggests that the endothelial cells come fr
