Adult stem cells taken from bone marrow can develop into kidney cells, British scientists have discovered.
Bone marrow stem cells, which are immature blood cells, have already been shown to transform into liver, nerve and muscle cells.

Both adult and embryonic stem cells have enormous medical potential due to their ability to mature into a wide range of different tissues, which could then be transplanted. However, ethical considerations have prompted many to argue that research on embryonic stem cells, which requires the destruction of human embryos, should not receive US government support.

Bush must weigh the ethical problems of using embryonic stem cells against their healing potential and so a great deal hinges on whether adult stem cells can be shown to be as versatile as their less mature cousins, embryonic stem cells. The latter are thought to be able to develop into any type of cell.

On Monday, Pope John Paul II met Bush near Rome and condemned the “evils” of research on embryonic stem cells. Bush’s decision — the most politically difficult he has faced in a brief presidency marked by difficult decisions — is thought to be imminent.