Modeling endothelial glycocalyx and its interaction with blood flow

It is sound knowledge in biophysics that a good model for blood is made up of a simple newtonian liquid and one-kind deformable particles [1]. However, such an approach turns to be not enough suitable for a complete description of blood circulation. In vivo observations, in fact, pointed out that red blood cell (RBC) velocity is slower than in in vitro experiments with glass capillary tubes of the same size [2] and an explanation for such an effect needs the model to embrace further details. The reason of the slowing down has been ascribed to a recently discovered network: glycocalyx, an ensemble of polymers grafted to the inner surface of vessel walls (endothelium) [3]. The name “glycocalyx”explicitly refers to one of the major component of such an etherogeneous structure, glucose, that, together with proteins and other kinds of organic macromolecules, form the most relevant compounds (glycoproteins, glycoaminoglycans) this network is constituted by. The first in vivo measurement of endothelium glycocalyx dates back to 1996 [4] and from then on increasingly refined experimental techniques [5] have settled that glycocalyx covers all mammalian blood vessels and ranges from 150nm to 400nm, meaning that its width is no more then 10% of the tube diameter even in the smallest capillaries. Target of this project is to model glycocalyx dynamics and its interaction with in-blood flowing particles and RBCs. In fact, although glycocalyx relevance is beyond any doubt, its functions are still under study and wait for rigorous prooves. Among the suggested hypotheses [3] I mention the major ones: