Adult stem cells may be redefinable.

New research indicates that adult neural stem cells--previously thought to be committed to becoming either neurones, astrocytes, or oligodendrocytes--can de-differentiate and reinvent themselves as haemopoietic precursors (Science 1999;985:471, 534-7).

This finding raises the possibility that adult human stem cells may some day be coached to grow into organs, regenerate damaged tissue, or reconstitute the immune system.

The problem of immune rejection may also be circumvented if an individual's own cells can be used.

It also means that the need for fetal cells as a source of stem cells for medical research may soon be eclipsed by the more readily …