While politicos continue to debate the ethics of expanding research on embryonic stem cells, the scientific debate persists as to whether adult stem cells are multipotent, or if they even need to be in order to be therapeutically relevant. Two Hot Papers appearing within a span of two weeks in early 2003 further revealed that one might in fact be able to teach an old cell new tricks. Eva Mezey and colleagues at the National Institutes of Health and Johns Hopkins, and Helen Blau's group at Stanford University, showed that transplanted bone marrow-derived stem cells could not only populate the human brain, but also contribute – either through transdifferentiation or fusion – to neural cells.12
Both studies took advantage of gender-mismatched bone marrow transplants, which leave a signature Y chromosome from male donor cells in female brains. Mezey and colleagues examined postmortem samples from female leukemia patients and found neuron-like ...
