Confinement dependent chemotaxis in two-photon polymerized linear migration constructs with highly definable...

Area of Science:

• Cellular biology
• Biophysics
• Microfluidics

Background:

• Dendritic cell chemotaxis guides immune responses.
• Cell migration occurs in complex tissue environments with varying pore sizes.
• Understanding migration velocity dependence on pore size and gradient steepness is crucial.

Purpose of the Study:

• To investigate how channel dimensions and chemokine gradient steepness affect dendritic cell migration velocity.
• To decouple the effects of spatial confinement and gradient enhancement in microfluidic channels.
• To elucidate the primary drivers of directed cell migration in engineered microenvironments.

Main Methods:

• Two-photon polymerization used to create microchannels (10x10 μm² to 20x20 μm²) in chemotaxis chips.
• Long-term (≥42 hours) live cell imaging to track dendritic cell migration.
• Finite element modeling to simulate chemokine diffusion and gradient formation.
• Introduction of micro-scale 'venting slits' to modulate chemokine gradients.

Main Results:

• Faster migration observed in narrower channels, despite increased cell deformation.
• Modeling showed enhanced chemokine gradients due to cells obstructing diffusion in confined spaces.
• Venting slits significantly reduced gradient accentuation, leading to slower migration speeds.
• Migration speeds in slitted 10x10 μm² channels matched unslitted 20x20 μm² channels.

Conclusions:

• Chemoattractant gradient steepness, not just channel size, strongly influences dendritic cell migration velocity.
• Microfluidic devices with venting slits can decouple spatial confinement and gradient effects.
• Findings highlight the importance of chemokine gradient dynamics in directed cell movement within tissues.