Quantitative absorption cytometry for measuring red blood cell hemoglobin mass and volume

Area of Science:

• Biomedical Optics
• Cellular Biology
• Microfluidics

Background:

• Clinical hematology analyzers often require cells to be sphered for accurate volume and hemoglobin measurement.
• Analyzing red blood cells (RBCs) in their native physiological shape is crucial for understanding cellular health and disease.
• Existing methods may struggle with accurate quantification of RBC indices when cells exhibit non-spherical morphologies.

Purpose of the Study:

• To introduce a novel optical system, the quantitative absorption cytometer (QAC).
• To accurately measure the volume and hemoglobin mass of individual red blood cells in their native physiological shape.
• To assess the QAC's performance against clinical hematology analyzers and its utility in studying RBCs under osmotic stress.

Main Methods:

• Developed a quantitative absorption cytometer (QAC) utilizing a transmission light microscope and a color camera.
• Human RBCs were suspended in a refractive index-matching absorbing buffer and flowed through a microfluidic channel.
• Independent retrieval of cell volume and hemoglobin mass using red and blue LED illumination, with image analysis providing height and mass maps.

Main Results:

• The QAC demonstrated good agreement with standard clinical hematology analyzers for RBC indices.
• The QAC achieved a smaller coefficient of variation for hemoglobin concentration compared to clinical analyzers.
• The system accurately measured RBCs under hypertonic and hypotonic conditions, demonstrating shape invariance.

Conclusions:

• The QAC is a robust optical system for precise, shape-independent measurement of RBC volume and hemoglobin mass.
• This technology provides valuable quantitative morphological data for individual cells and population analysis.
• The QAC offers an advancement over traditional methods, particularly for analyzing RBCs with varying shapes and under osmotic stress.