High content evaluation of shear dependent platelet function in a microfluidic flow assay.

Area of Science:

• Biomedical Engineering
• Hematology
• Microfluidics

Background:

• Conventional flow assays for platelet function demand high blood volumes and offer low throughput, limiting their clinical and drug screening utility.
• Platelet function assays are crucial for diagnosing bleeding disorders and evaluating antiplatelet therapies.

Purpose of the Study:

• To develop a microfluidic flow assay for measuring platelet function using a small volume of whole blood.
• To enable high-throughput screening and clinical monitoring of platelet activity and antiplatelet agents.

Main Methods:

• A novel microfluidic device was fabricated using a hydrated microcontact stamping method to pattern collagen thin films (CTF) on glass substrates.
• Micropatterned CTF spots (20, 50, 100 μm) were exposed to whole blood (50 μL) across physiologic shear rates (50-920 s⁻¹).
• Platelet accumulation metrics (lag time, growth rate, total accumulation) were quantified using Hoffman modulation contrast microscopy.

Main Results:

• A minimum spot size of 20 μm was required for stable platelet adhesion under flow, indicating a threshold injury size.
• The microfluidic assay successfully measured platelet function metrics with high content from ~300 micropatterned spots.
• The assay demonstrated sensitivity to platelet adhesion and aggregation dynamics at various shear rates.

Conclusions:

• The developed microfluidic assay offers a high-throughput, low-volume alternative to conventional platelet function tests.
• This technology has significant potential for identifying platelet function defects and for the screening, monitoring, and dosing of antiplatelet medications.
• The assay's ability to mimic physiologic shear rates enhances its relevance for clinical applications.