Abstract
In the past few years stem cells normally present within the bone marrow have been shown to have considerable plasticity in the repertoire of the cells that they produce. They are capable of producing specific lineages of cells not only of the blood, but also contribute usefully to lineages of other organs. In the kidney, studies in humans and rodents provide evidence for the presence of bone marrow-derived 're-programmed' cells, but it remains possible that the cells that arrive and re-differentiate are no longer stem cells (quiescent cells, not actively proliferating). Nevertheless, the fact that appropriately differentiated cells are delivered deep within the kidney simply by injection of bone marrow cells should make us think differently about the way these organs regenerate and repair. Migratory pathways for multipotential stem cells could be exploited to effect repair using an individual's own stem cells, perhaps after gene therapy. It is clear also that a transplanted organ would in time become affected by the genetic susceptibilities of the recipient, because of phenotypes that are expressed when trafficking cells engraft and differentiate.