Inertial Microfluidics Enables Functional Analysis of Neutrophils Isolated from Ultralow Blood Volume Samples.

Area of Science:

• Biomedical Engineering
• Immunology
• Microfluidics

Background:

• Immune cell function monitoring is crucial but hindered by the need for large blood volumes.
• Traditional white blood cell counts lack the functional relevance of direct immune cell analysis.
• Existing methods for isolating immune cells often require significant sample volumes, limiting applications.

Purpose of the Study:

• To develop a sample-sparing microfluidic platform for isolating leukocytes from minimal blood volumes.
• To assess the purity, recovery, and viability of leukocytes isolated using the developed platform.
• To validate the functional integrity of isolated neutrophils for downstream immune assays.

Main Methods:

• Development of an inertial microfluidic platform capable of processing 10 μL of blood.
• Isolation and purification of leukocytes, with a focus on neutrophils.
• Functional assessment of isolated neutrophils using assays such as phagocytosis, ROS production, and NETosis.
• Testing platform compatibility with standard laboratory workflows (flow cytometry, cell culture).
• Demonstration of platform versatility with various sample types (mouse blood, human capillary blood).

Main Results:

• Leukocyte isolation achieved with approximately 80% purity, >90% in-device recovery, and >95% viability.
• Isolated neutrophils maintained native phenotypes, with no significant changes in CD62L and CD11b expression.
• Functional assays confirmed that isolated neutrophils retained their phagocytic capacity, ROS production, and NETosis capabilities.
• Successful isolation of leukocytes from mouse and human capillary blood samples, demonstrating broad applicability.

Conclusions:

• The developed microfluidic platform effectively isolates functional leukocytes from small blood volumes (10 μL).
• The platform preserves neutrophil viability and function, making it suitable for sensitive immune monitoring.
• This technology offers a versatile solution for immune cell analysis in research and clinical settings, especially when sample volume is limited.