Red Blood Cells
We are exploring the stacking of red blood cells into rouleaux - that is, coin like rolls - due to depletion interactions. The presence of rouleaux in a patient's blood is a non-specific disease indicator. The formation of rouleaux is associated with the over expression of soluble proteins, but it is not known if the driving mechanism is proteins binding the cells together (enthalpy) or simply depletion forces (entropy). Using a coarse-grained model where a red blood cell is represented by 27 spherical particles joined together, we have shown that rouleaux do form for physical reasonable volume fractions of smaller proteins (see image). This result demonstrates that depletion forces may be a driving mechanism for the formation of rouleaux. We are also exploring the details of rouleaux formation in terms of the kinetics and equilibrium statistics in the hopes of being able to discern between the different driving mechanism for rouleaux formation.
Nehring A, Shendruk TN , de Haan HW, "Morphology of depletant-induced erythrocyte aggregates", Soft matter. 14(40): 8160-817, 2018.
Shendruk TN, Bertrand M, de Haan HW, Harden JL, Slater GW, "Simulating the Entropic Collapse of Coarse-Grained Chromosomes", Biophysical Journal, 108(4), 810-820 (2015).
Shendruk TN, Bertrand M, Harden JL, Slater GW, de Haan HW,"Coarse-Grained Molecular Dynamics Simulations of Depletion-Induced Interactions for Soft Matter Systems", Journal of Chemical Physics, 141, 244910 (2014).