Red Blood Cells Take On Many-Sided Shape During Clotting

Shiva Mudide

Author: John Weisel
Date Published: December 13, 2013
Link: http://www.sciencedaily.com/releases/2014/01/140109132133.htm

Summary: 

While studying how blood clots contract John W. Weisel, Ph.D. and colleagues, discovered a new geometry that red blood cells assume, when compressed during clot formation.The Penn team found that red blood cells can be compressed into many-sided, closely-packed polyhedral structures, instead of their free flowing concave, disc shape. 

Furthermore they came upon the fact that the fibrin and platelets that make up clots lie primarily on the clot exterior, with the red blood cells crowded within the clot interior. Clots may have a seal and help prevent vascular obstruction, but get resistance to drugs that break down fibrin, a common treatment option for heart attacks and strokes. Little was known about the structure of contracted clots or the role of red blood cells in the contraction process, but they found that "contracted blood clots develop a mesh work of fibrin and platelets on the exterior of the clot and a close-packed, tessellated array of compressed polyhedral erythrocytes within," says Weisel.This shape is likely taken on by the red blood cells when contracted or pushed together when the platelets compress a clot so as to decrease volume, surface energy, or bending energy. 

Clinically, physicians need to inject thrombolytic agents to rapidly break up clots that obstruct blood flow, in coronary arteries to treat a heart attack, or in the arteries to the brain to treat a stroke. These clots develop resistance to being broken up, which is one reason why early intervention is so important. Clot contraction could be a target of intervention to prevent the formation this resistance. 

Connection:

We learned how blood can clot in order to heal from ruptures to the vessels or capillaries, as well as how plaque build-up can lead to heart attack or stroke. When a vessel ruptures, platelets clump at the injured site and release clotting factors. This activates a series of reactions leading to the production of the protein fibrin, which forms a "patch." This article explains how the vessel can become resistant to drugs that break down fibrin in order to unclot a vessel to help prevent a heart attack or stroke. This can thus be an issue. Also, the shape of the blood cells as described in the article leads to a tighter fit with the fibrin, making the "patch" more effective. We also learned that atherosclerosis, the narrowing of the arteries results from plaque building up inside the artery wall. As the pathway narrows, blood pressure increases. Sometimes the narrowing completely blocks the flow of blood. If such a blockage occurs in one of the coronary arteries, the main arteries that supply the heart, the heart becomes deprived of oxygen and other nutrients. The article explains how physicians can inject thrombolytic agents to rapidly break up clots that obstruct blood flow to treat this.