Investigating cancer stem cells may uncover useful targets for new selective cell destruction methods, such as this one: researchers "have identified the first human bladder cancer stem cell and revealed how it works to escape the body's natural defenses. ... [the gene] CD47 works to prevent leukemia cells from being engulfed by macrophages by binding to a molecule on the surface of the macrophage. Blocking this interaction with an antibody specific for CD47 allows the macrophages to swallow the leukemia cells. When [researchers] tried a similar experiment with the bladder cancer stem cells in a test tube, the same thing happened - human macrophages began to destroy the cancer cells. ... Leukemia is totally different from the kind of epithelial cancer we see in the bladder, so it was very exciting to see that these two kinds of cancer stem cells use a similar mechanism to escape the macrophages. ... The researchers are now investigating whether CD47 is expressed at high levels on other cancer stem cells and pondering ways to help circulating macrophages better infiltrate solid tumors - always with an eye towards therapy."