Anyone who fishes knows that if you hope to catch the “big ones,” you need to have the right bait. That’s especially true if what you need to snag is outnumbered significantly by species you’re not interested in. Nowhere is this more apparent than in blood, where the rare adult stem cells are swimming in an ocean of other materials. For Dr. Michael King, an Associate Professor of Biomedical Engineering at the University of Rochester, the secret to pulling out the prized catches is employing a class of adhesive, membrane-bound glycoproteins known as selectins. In the body, these molecules play roles “grabbing” leukocytes and directing them to the site of wounds. One class of these sticky proteins helps stem cells to interact with bone cells, aiding the process of stem cell transplantation. Reckoning that materials coated with stem cell-specific-selectins might provide a way to catch these elusive quarry in flowing blood, King and colleagues implanted “baited” devices in rats and, after retrieving them, discovered they contained 25% stem cells. Traditional methods involving stimulating the body to produce stem cells and centrifugation produce 3-4% stem cells at best. Writing in the March 3 issue of the British Journal of Haematology, King reports that the method looks to have wide applicability. Equally exciting are current efforts to identify selectins specific to cancer cells. Dr. King envisions one day implanting a device in the body that selectively removes metastatic cells, thus providing a means of early identification of cancer, as well as a way of “cleaning” the blood of problem cells.