How viscoelastic is human blood plasma?

Area of Science:

• Biophysics
• Fluid Dynamics
• Biomaterials Science

Background:

• Blood plasma was traditionally considered a Newtonian fluid.
• Recent studies suggest plasma possesses viscoelastic properties, evidenced by filament collapse and microchannel flow.
• Conventional rheometers struggle to characterize plasma's viscoelasticity due to its low viscosity.

Purpose of the Study:

• To accurately predict the rheological response of human blood plasma in complex flows.
• To quantitatively estimate plasma's viscoelastic properties in shear and extensional flows.
• To identify the primary protein responsible for plasma's elasticity.

Main Methods:

• Computational rheology
• Molecular-based constitutive modeling
• Analysis of extensional and constriction flows

Main Results:

• Plasma exhibits ultra-short relaxation times (10^-3–10^-5 s).
• Elasticity dominates in high shear and extensional rate flows, like those in microvessels.
• Plasma shows significant strain hardening due to protein stretching, with fibrinogen identified as the likely elastic contributor.

Conclusions:

• Human blood plasma demonstrates bulk viscoelasticity.
• This non-Newtonian behavior is significant in high-flow conditions.
• Plasma's viscoelasticity must be considered in whole blood flow analysis.