Erythropoietin expands a stromal cell population that can mediate renoprotection.

Recent studies have demonstrated that erythropoietin (EPO) receptors are expressed on tubular epithelial cells and that EPO can protect tubular cells from injury in vitro and in vivo. Separate studies have demonstrated that marrow stromal cells (MSCs) exert a renoprotective effect in ischemia-reperfusion and cisplatin tubular injury via the secretion of factors that reduce apoptosis and increase proliferation of tubular epithelial cells. In the present study we demonstrate that MSCs express EPO receptors and that EPO can protect MSCs from serum deprivation-induced cell death and can stimulate MSC proliferation in vitro.