Team Fully Characterizes EPC Cells

Experts at the Northwestern University announce that they have finally managed to crack the mystery surrounding one of the most potent and little-researched line of stem cells. Called endothelial progenitor cells (EPC), these special structures can usually be found in the bloodstream, and they are in charge of producing new endothelial cells. These, in turn, form the type of tissue that lines the walls of blood vessels, and are therefore crucially important to the human body. The finding was made at the NU McCormick School of Engineering, and details of it appear in the latest online issue of the respected scientific journal Stem Cells.

One of the main medical disorders that could receive a new cure following the new investigation is called peripheral arterial disease. It affects between 8 and 12 million people in the United States alone. This is roughly equivalent to one in 20 individuals. During their experiments, the researchers wanted to learn whether progenitor cells can differentiate to both look and act like the cells they were supposed to create, but in a Petri dish, rather than in the human body. So they took EPC cells, placed them in a culture, and then watched them to see if they would differentiate into adult, endothelial cells.

“Normally, stem cells are not studied in the context of improving vascular grafts for bypass surgery. Therefore, we had to develop new tests to assess their use in this application. We looked at the function of the cells on a citric acid-based polymer, which will be the basis for a new generation of bioengineered vascular grafts,” says the senior author of the new journal entry, Guillermo Ameer. He is also an associate professor of biomedical engineering and surgery at the university. “These new tests show that these endothelial-like cells can inhibit blood clotting and can prevent platelets from adhering to their surface. But if you antagonize the cells or stimulate them, they will also respond the same way that an endothelial cell would and will clot blood if needed,” the expert adds.

The new work also sets the foundation for a new type of bioengineering, and namely building a tissue-based vascular graft, that could address blood vessel problems directly inside the body. At this point, existing technologies only work well in large veins and arteries, but fail inside smaller ones. “These small-diameter synthetic grafts are more prone to blood clots and other complications, especially over time. It's thought that a tissue-engineered graft would allow us to preserve many of the body's natural defenses against these complications,” Ameer concludes.