Implantable Device Causes Metastasizing Cancer Cells To Self-destruct

Selectin proteins on the inner walls of blood vessels act like velcro to bind selectin ligands on circulating leukocytes with marginal affinity. This causes the leukocytes to slow down and begin rolling along the inner surface of the vessel wall. During this rolling motion, transitory bonds are formed and broken between selectins and their ligands. The surface membranes of metastasizing cancer cells also contain selectin ligands. In the experimental setting, during the brief time when cancer cells interacted with the walls of the coated flow chamber, they were exposed to a protein called TRAIL (tumor necrosis factor related apoptosis-inducing ligand) that initiated an apoptotic process by binding briefly to so-called "death receptors" on the cancer cell membranes.

Results published in the November 14, 2008, online edition of the journal Biotechnology and Bioengineering, revealed that a one hour rolling exposure to a functionalized TRAIL and E-selectin surface was sufficient to kill 30% of circulating cancer cells compared to static conditions in which four hours of exposure was necessary to kill 30% of the cells. There was no significant effect of TRAIL on hematopoietic stem cells or other normal blood cells.

"This has never been tried before. It is a whole new way of approaching cancer treatment, said senior author Dr. Michael King, professor of biomedical engineering at Cornell University. "It is a little more sophisticated than just filtering the blood, because we are not just accumulating cancer cells on the surface. There is a lot of work yet to be done, of course, before this actually helps people -- but this is how it starts. The actual physical device, when it gets eventually tested in humans, will probably look a lot like an arteriovenous shunt with our protein coating."

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