Editing Rheology (section)

==== Red blood cell aggregation ====
There are two current major hypotheses to explain blood flow predictions and [[shear thinning]] responses. The two models also attempt to demonstrate the drive for reversible red blood cell aggregation, although the mechanism is still being debated. There is a direct effect of red blood cell aggregation on blood viscosity and circulation.<ref name="Lee-2017">{{Cite journal |last1=Lee |first1=Kisung |last2=Wagner |first2=Christian |last3=Priezzhev |first3=Alexander V. |date=2017 |title=Assessment of the "cross-bridge"-induced interaction of red blood cells by optical trapping combined with microfluidics |journal=Journal of Biomedical Optics |volume=22 |issue=9 |pages=091516 |doi=10.1117/1.JBO.22.9.091516 |pmid=28636066 |bibcode=2017JBO....22i1516L |s2cid=27534435 |doi-access=free }}</ref> The foundation of [[hemorheology]] can also provide information for modeling of other biofluids.<ref name="Beris-2021" /> The bridging or "cross-bridging" hypothesis suggests that macromolecules physically crosslink adjacent red blood cells into rouleaux structures. This occurs through adsorption of macromolecules onto the red blood cell surfaces.<ref name="Beris-2021" /><ref name="Lee-2017" /> The depletion layer hypothesis suggests the opposite mechanism. The surfaces of the red blood cells are bound together by an osmotic pressure gradient that is created by depletion layers overlapping.<ref name="Beris-2021" /> The effect of rouleaux aggregation tendency can be explained by [[hematocrit]] and fibrinogen concentration in whole blood rheology.<ref name="Beris-2021" /> Some techniques researchers use are optical trapping and microfluidics to measure cell interaction in vitro.<ref name="Lee-2017" />