Contribution of bone marrow-derived cells in renal repair after acute kidney injury.

Acute kidney injury (AKI) is a frequent clinical problem with a high mortality rate, generally caused by ischemic insults. Nevertheless, the kidney has a remarkably high capacity to regenerate after ischemic injury. Tubular cells can restore renal function by proliferation and dedifferentiation into a mesenchymal cell-type, but also stem cells residing in bone marrow (BM) have been suggested to contribute. Considerable progress has been made in the development of different techniques to study the role of BM-derived stem cells in renal regeneration after AKI. Trans-differentiation of BM cells to functional tubular epithelium has been demonstrated previously, however, beneficial effects of BM transplantations may have been accelerated by irradiation of mice prior to transplantation and kidney injury. Recent studies support a paracrine or endocrine role of BM-derived cells, in which an improvement of renal function is observed without direct involvement in tubular epithelial engraftment. On the other hand, BM cells have also shown not to improve renal function despite their tubular engraftment. This review gives an overview of the recent progress in studying the role of BM-derived cells as therapeutic strategy in renal tubular repair after acute injury.