Rheology and Mechanics of Blood Flow Systems

Blood flow is governed by the interplay between hemodynamic forces and the complex rheological properties of blood, a heterogeneous suspension of plasma, erythrocytes, leukocytes, platelets and macromolecules. At physiological shear rates, blood exhibits non-Newtonian, shear-thinning behaviour arising from reversible aggregation of red blood cells and deformation of individual erythrocytes. In large arteries, pulsatile pressure and vessel elasticity shape flow patterns and wall shear stress, influencing vascular remodelling and endothelial function. In microvessels below 300 µm in diameter, the Fåhræus–Lindqvist effect lowers apparent viscosity, while cell margination and phase separation at bifurcations control the distribution of formed elements. Mechanical properties of erythrocytes—membrane elasticity, cytoskeletal stiffness and internal viscosity—critically determine capillary transit times and oxygen delivery. Advances in microfluidic device fabrication, high-speed imaging and computational modelling have enabled multi-scale investigations from single-cell deformation to organ-level circulation. These insights underpin the development of diagnostic tools for blood disorders, optimisation of drug delivery in microchannels and design of blood-mimicking fluids for medical devices. A comprehensive understanding of blood rheology and mechanics is therefore central to tackling cardiovascular disease, tissue engineering and the translation of novel therapeutic strategies.

Research from Nature Portfolio

Recent studies have revealed that arteriolar segments contribute substantially to oxygen extraction in cerebral microcirculation, challenging the traditional view that capillaries dominate gas exchange. Combining intravascular oxygen tension imaging with flow measurements and numerical modelling, researchers demonstrated that a large fraction of baseline oxygen is released from small arterioles, with capillaries acting as a reserve under increased metabolic demand. In parallel, innovative optical-tweezers experiments applied to diabetic cohorts have quantified the reduced deformability of red blood cells in type 2 diabetes mellitus and in diabetic retinopathy. By measuring changes in cell length under calibrated laser-induced stress, these investigations have established a quantitative deformability index that correlates with disease severity and may serve as a prognostic marker. Together, these contributions illustrate the power of integrating high-resolution measurement techniques with theoretical frameworks to unravel the mechanistic underpinnings of blood flow regulation.

Rheology and Mechanics of Blood Flow Systems publication trend

The graph below shows the total number of articles in rheology and mechanics of blood flow systems across all publications each year (not limited to Nature Index journals).

Technical terms

Non-Newtonian fluid: A fluid whose viscosity varies with shear rate, as in blood, where viscosity decreases at higher shear.

Shear-thinning: A property of fluids that exhibit reduced viscosity when subjected to increasing shear stress.

Ektacytometry: A technique measuring red blood cell deformability by analysing cell elongation under controlled shear flow.

Fåhræus–Lindqvist effect: The decrease in apparent blood viscosity observed in small vessels due to axial migration of red blood cells.

Deformability index: A quantitative metric of red blood cell flexibility, defined by the change in cell shape or length under applied force.

References

1. Large arteriolar component of oxygen delivery implies a safe margin of oxygen supply to cerebral tissue. Nature Communications (2014).
2. Assessment of red blood cell deformability in type 2 diabetes mellitus and diabetic retinopathy by dual optical tweezers stretching technique. Scientific Reports (2016).
3. Simulation studies on hemodynamic models for blood flow. International Journal of Mathematics and Computer in Engineering (2024).
4. Altered RBC deformability in diabetes: clinical characteristics and RBC pathophysiology. Cardiovascular Diabetology (2024).
5. Deformation and dynamics of red blood cells in flow through cylindrical microchannels. Soft Matter (2014).