# Suspension physics govern the multiscale dynamics of blood flow in sickle cell disease

## TL;DR

This study explores how blood flow is affected in sickle cell disease by analyzing red blood cell properties and their behavior in microfluidic systems.

## Contribution

The study introduces a microfluidic platform to measure red blood cell properties and flow dynamics in the same patient samples, revealing suspension physics in sickle cell disease.

## Key findings

- Effective blood viscosity is explained by the proportion of stiff red blood cells.
- Emergent rheology is governed by spatiotemporal cell organization and localized jamming under hypoxia.
- Cell mechanical heterogeneity drives aberrant blood flow in diverse patient profiles.

## Abstract

From diabetes to malaria, altered blood flow contributes to poor clinical outcomes. Heterogeneity in red blood cell (RBC) properties within and across individuals has hindered our ability to establish the multiscale mechanisms driving pathological flow dynamics in such diseases. To address this, we develop microfluidic platforms to measure RBC properties and flow dynamics in the same blood samples from patients with sickle cell disease (SCD). We find that effective blood viscosity across individuals is explained by the proportion of stiff RBCs, exhibiting qualitative similarities to rigid-particle suspensions, despite considerable mechanical heterogeneity. By combining simulations with spatially resolved measurements of cell dynamics, we show how features of emergent rheology are governed by spatiotemporal cell organization, via margination at intermediate oxygen tensions, and localized jamming caused by spatial hematocrit variations under hypoxia. Our work defines the suspension physics underlying pathological blood flow in SCD and, more broadly, emergent rheology in heterogeneous particle suspensions.

Cell mechanical heterogeneity is established as a main driver of aberrant blood flow across diverse patient profiles.