Stem Cells' Malevolent Side

Even as the ethical debate rages over the use of stem cells in research, scientists are continuing to discover how understanding such cells can be medically important. Stem cells are immature cells that have the capability of developing into a wide range of adult cells, thus raising the possibility that they could be used to regenerate organs damaged by disease or trauma.

However, stem cells also have a malevolent side, as has been discovered by Duke researchers studying the origin of the aggressive, deadly childhood brain cancer, medulloblastoma. In their studies, the scientists discovered brain stem cells in the cerebellum--the brain region where medulloblastomas arise. Their findings suggest that the uncontrolled proliferation of such stem cells could cause medulloblastomas, which could provide a starting point for understanding the still-mysterious cancer, say the researchers. And, such understanding could enable development of more targeted, less toxic treatments that thwart such rogue stem cells, they say.

In an article in the June 2005 issue of Nature Neuroscience, Robert Wechsler-Reya and his colleagues described how they discovered the stem cells while studying the development of "granule cells," the most common cell type in the cerebellum. Some medulloblastomas had been believed to originate from granule cells. In purifying the granule cells, what the scientists first believed to be contaminating cells turned out, surprisingly, to be stem cells.

Building on their discovery, the researchers hope to create animal models of medulloblastoma by mutating such stem cells to make them cause the cancer. Such animal models will give the researchers the ability to test drugs that shut down the culprit genes that drive the stem cells to over proliferate. Such targeted drugs would be far safer than current chemotherapy drugs that target all dividing cells--a particularly toxic strategy in children.