Coddling cancer

The brain pampers not just its normal stem cells, but also the cancer stem cells responsible for most tumor growth, report Christopher Calabrese, Richard Gilbertson (St. Jude Children's Research Hospital, Memphis, TN), and colleagues. The study is the first to demonstrate that tumors contain a stem cell niche and may help researchers devise ways to evict the cells from their cushy digs.

Neighboring cells cradle stem cells within a structure termed a niche. Besides providing protection, niche cells release factors that maintain stem cells' ability to divide. But researchers weren't certain whether cancer stem cells (CSCs) also reside within niches in tumors.

Using multiphoton laser scanning microscopy, Gilbertson and colleagues observed that CSCs adhere to capillaries within brain tumors, suggesting that the vessels fashioned a niche. To determine whether this interaction was vital for...