Assembly of multiple cell gradients directed by three-dimensional microfluidic channels

Area of Science:

• Biomedical Engineering
• Cell Biology
• Microfluidics

Background:

• Precise control over cell distribution is crucial for biological studies and tissue engineering, especially for organ-on-a-chip applications.
• Existing methods for creating cell gradients can be complex or lack fine control over gradient profiles.

Purpose of the Study:

• To develop a simple and versatile three-dimensional (3D) microfluidic strategy for generating controllable cell density gradients.
• To demonstrate the ability to create various gradient profiles and multiple overlapping gradients for advanced tissue reconstruction.

Main Methods:

• Utilized a 3D stair-shaped polydimethylsiloxane (PDMS) microchannel for cell sedimentation.
• Fabricated microchannels with controlled layer heights to achieve specific gradient profiles (exponential, piecewise linear).
• Employed sequential seeding to generate overlapping cell gradients on a single substrate.

Main Results:

• Successfully generated controllable cell gradients within 10 minutes using sedimentation in the 3D microchannel.
• Achieved diverse gradient profiles (exponential, piecewise linear) by precisely controlling microchannel layer heights.
• Demonstrated the creation of two overlapping cell gradients with pre-defined designs using sequential seeding.
• Showcased that cell density gradients influence cell behavior and resistance in a cytotoxicity assay.

Conclusions:

• The proposed 3D microfluidic strategy offers a straightforward and adaptable method for establishing controlled cell density gradients.
• This technique provides a new pathway for reconstructing functional tissues and advancing organ-on-a-chip technologies.