Cell stretching measurement utilizing viscoelastic particle focusing

Area of Science:

• Biophysics
• Cell Mechanics
• Microfluidics

Background:

• Accurate measurement of cell stretching is crucial for understanding cell mechanics and disease.
• Conventional methods using Newtonian media face challenges with cell distribution and controlled stretching.

Purpose of the Study:

• To develop an efficient and accurate method for measuring cell stretching.
• To utilize viscoelastic properties of a medium for improved cell focusing and stretching in microfluidic devices.

Main Methods:

• Cells were suspended in a biocompatible viscoelastic medium (poly(vinylpyrrolidone) in phosphate-buffered saline).
• A cross-slot microchannel was used to apply extensional flow for cell stretching.
• Computational simulations were employed to validate the method's accuracy and cell trajectory control.

Main Results:

• Over 95% of red blood cells (RBCs) were successfully focused and stretched at the channel centerline.
• Viscoelastic medium significantly homogenized cell trajectories, preventing random lateral distributions.
• Demonstrated characterization of RBC deformability differences after heat treatments and nutrient starvation in stem cells.

Conclusions:

• The developed method provides rotational-free cell stretching along a shear-free centerline, enhancing measurement accuracy.
• This technique is applicable for assessing cell deformability in various conditions, including disease states like malaria and diabetes.
• The method holds promise for monitoring cell quality in stem cell therapeutics and diagnosing pathophysiological changes.