Capillary plexuses are vulnerable to neutrophil extracellular traps

Area of Science:

• Biomedical Engineering
• Hematology
• Microfluidics

Background:

• Capillary plexuses ensure oxygen delivery, with redundancy against clots.
• Severe inflammation can cause secondary organ injury despite robust vasculature.
• Neutrophils' role in inflammation-induced organ injury is not fully understood.

Purpose of the Study:

• To investigate the impact of neutrophil extracellular traps (NETs) on blood flow within capillary-like microfluidic networks.
• To determine if NETs affect red blood cell and plasma traffic independently.

Main Methods:

• Utilized microfluidic networks mimicking capillary plexus geometry.
• Introduced NETs from activated neutrophils into the networks.
• Observed and quantified red blood cell and plasma flow dynamics in vitro.

Main Results:

• NETs significantly decoupled red blood cell traffic from plasma flow.
• A small number of neutrophils (under 200) caused widespread disruption of red blood cell traffic (over 50% of a 0.6 mm² network).
• NETs impeded blood flow even in the presence of anticoagulants.

Conclusions:

• NETs can obstruct microvascular blood flow by altering red blood cell dynamics.
• This NET-induced flow perturbation may represent a novel mechanism for tissue hypoxia and secondary organ injury during severe inflammation.
• Findings suggest a potential cause for organ damage in patients on anticoagulant therapies.