Selectin Adhesion Molecules for Trapping Stem Cells and Killing Cancer

Selectins are peptide cell adhesion molecules that line blood vessel lumens and attach to white blood cells (L-selectin) and platelets (P-Selectin), as well as stem cells and cancer cells.

The ability of selectins to bind stem cells and cancer cells gave researcher Michael King an idea--or two ideas, actually. King realized that he could harvest stem cells from the circulation using selectins, and he also had an idea how he could use selectins to trap and kill metastasizing cancer cells.

he learned that when a cancer cell breaks free of a primary tumor and enters circulation, it flow through the bloodstream to a remote organ, then leaves the bloodstream and forms a secondary tumor. This is how cancer spreads. He put these facts together with one more, very important fact: the selectins grab onto a specific carbohydrate on the surfaces of white blood cells, stem cells, and cancer cells. Associate Professor King decided to capture stem and cancer cells before the selectins release them.

....Because bone marrow stem cells stick to selectin surfaces more strongly than other cells, King’s group coated a slender plastic tube with selectin. They then did a series of lab experiments, both in vitro and in vivo using rats, with this selectin-coated tube to filter the bloodstream for stem cells. It worked, and the King Lab discovered that they could attract a large number of cells to the wall of their selectin-coated device, and that 38% of these captured cells were stem cells. King envisioned a system by which doctors could remove stem cells from the bloodstream by flowing the cells through a device, and make a more concentrated mixture containing, say, 20-40 percent stem cells. These stem cells could then be used for tissue engineering or bone marrow transplantation.

....Another exciting application of King’s invention is filtering the blood for cancer cells and triggering their death, an innovative, new method to prevent the spread of cancer. When someone has a primary cancer tumor, a small number of cancer cells circulates through the bloodstream. In a process called metastasis, these cells are transmitted from the primary tumor to other locations in the body, where they form secondary, cancerous growths.

As a cancer cell flows along the implanted surface, King’s device captures it and delivers an apoptosis signal, a biochemical way of telling the cancer cell to kill itself. Within two days, that cancer cell is dead. Normal cells are left totally unharmed because the device selectively targets cancer cells.

Source.

These are very interesting avenues of research using the selectins. The concept of inserting molecular traps into blood vessels to both harvest good cells and to destroy bad cells suggests even more intriguing experiments to be done in the near future.

Hat tip Medgadget.