A Materials Answer to Deadly Blood Clots

Photo of Chris Siedlecki

Penn State professor and researcher Chris Siedlecki works at the interface where the surface of devices meets the human body, and in particular where artificial materials contact the blood supply. In his laboratories for materials fabrication and characterization and biology at the Penn State Milton S. Hershey College of Medicine, he pursues the understanding of the cascade of events that occurs when proteins in the blood meet a foreign object, such as a vascular stent or heart assist device, in the circulatory system.

Blood thinning drugs used to control clotting, such as heparin and warfarin, carry serious risks. It is hard to control the amount of drug that will keep a patient from clotting without making the blood too thin. Too much of the drug can cause dangerous bleeding in critical locations, including the brain. Bleeding complications are found in as many as 20 percent to 50 percent of patients receiving some forms of blood contacting devices, such as artificial hearts.

Siedlecki and his colleagues have developed an approach that minimizes the binding force that attaches blood platelets to the surface of the implanted device. At the Penn State Nanofabrication Laboratory at University Park, the researchers used a soft lithography replication molding technique to create patterns of pillars 700 nm wide, roughly 1/2 to 1/4 the size of the platelets, and 700 nm apart. The tiny pillars limit the contact area between platelets and the material to only about 25 to 30 percent of what it would be in a smooth material. The 700-nm spacing showed a significant decrease in adhesion of platelets at low shear. With further refinements of the material, platelet adhesion was reduced by almost 10-fold, equivalent to the best results that can be achieved chemically.

For the significant number of people who cannot tolerate the anticoagulant drug regimen required for current device implants, a materials solution to blood clotting will come as an important development. Penn State has filed a U.S. patent application on the sub-micron texturing technique.

Christopher A. Siedlecki is associate professor of surgery and bioengineering, Alan J. Snyder is professor of surgery and bioengineering.

This research brief was featured in the brochure Biomedical Materials.