Source: Emory University
Summary: For the first time researchers have measured and mapped the key molecular forces on platelets that trigger blood clotting process.
Platelets are small colorless disk-shaped cells found in the blood whose job is to stop bleeding by sticking together and plug up a wound. A protein in the blood called fibrinogen acts like glue to stick platelets together as a clot forms. Each platelet consists of 70,000 copies of a receptor for fibrinogen on its surface. These receptors act like grappling hooks to lock onto fibrinogen. For the first time, researchers have from the Emory University measured and mapped the key molecular forces on platelets that trigger blood clotting process. They conclusively showed that a cell needs a targeted force of a magnitude of just a few piconewtons (5-20pN)to activate clotting process and found that platelets care about the direction of that force and that it has to be lateral. The research findings were published in the journal Proceedings of the National Academy of Sciences.
In order to explore the biomechanics of blood clotting, the research team anchored fibrinogen ligands onto a lipid membrane. On this surface, the ligands could slip and slide laterally, but resisted motion perpendicular to the surface. They then introduced platelets to this surface, where the platelets failed to activate and stick together. In contrast, when the fibrinogen ligands were anchored to a glass slide and unable to move laterally, the platelets rapidly activated clotting. The ability to map both the magnitude and orientation of forces on a cell provides a powerful tool for investigating not just blood clotting but a range of biomechanical processes, from immune cell activation and embryo development to the replication and spread of cancer cells.
Assoc. Prof. Khalid Salaita said, “We’ve developed a completely new way to see things that were not visible before”, “It’s a basic tool with broad applications to help understand why cells are doing things and maybe predict what they’re going to do next.”
More Information: Yun Zhang et al, “Platelet integrins exhibit anisotropic mechanosensing and harness piconewton forces to mediate platelet aggregation,” PNAS (2017). www.pnas.org/cgi/doi/10.1073/pnas.1710828115