Anisotropic short-range attractions precisely model branched erythrocyte aggregates

Area of Science:

• Biophysics
• Computational Biology
• Materials Science

Background:

• Red blood cells (erythrocytes) in plasma spontaneously aggregate into rouleaux.
• These aggregates often form complex, branched porous networks.
• Existing models fail to accurately predict the branched morphology of erythrocyte aggregates.

Purpose of the Study:

• To develop a model that accurately predicts the branched structures of red blood cell aggregates.
• To investigate the role of alignment-dependent forces in generating these structures.
• To analyze the scaling laws and phase transitions in red blood cell aggregation.

Main Methods:

• Simulations of a dimer system with alignment-dependent attractive forces.
• Derivation of a reaction kernel considering collision cross-section, velocities, and sticking probability.
• Analysis of structural properties, including branching, percolation, and size distribution.

Main Results:

• Alignment-dependent forces in dimer systems accurately generate branched structures resembling RBC aggregates.
• Simulations confirm sub-linear growth rates for rouleau size.
• The system exhibits percolated/giant cluster states, multiple mass-size scalings, and a transition to a branched phase.
• Decreasing depletion thickness increases percolation threshold and branching degree.
• The system self-organizes to produce universal power-law size distribution scaling.

Conclusions:

• Alignment-dependent forces are crucial for forming branched red blood cell aggregates.
• The developed model accurately captures key features of erythrocyte aggregation, including branching and scaling laws.
• This work provides insights into the self-organization principles governing complex biological structures.