Measuring cellular traction forces on non-planar substrates.

Area of Science:

• Biophysics
• Cell Biology
• Biomaterials

Background:

• Animal cells sense their environment through traction forces.
• Existing methods primarily focus on planar substrates using Green's function formalism.
• Measuring forces on complex, non-planar surfaces remains a challenge.

Purpose of the Study:

• To develop and validate a workflow for measuring cell traction forces on non-planar elastic substrates.
• To adapt force reconstruction techniques for complex geometries.
• To investigate the force-exerting behavior of cardiac myofibroblasts on wavy surfaces.

Main Methods:

• Micromoulding of wave-like polydimethylsiloxane substrates with embedded fluorescent beads.
• Feature vector-based tracking of marker beads to create a hexahedral mesh.
• Finite-element method (FEM) to solve the direct elastic boundary volume problem.
• Inverse problem solving using L1-norm residue and L2-norm Tikhonov regularization for force reconstruction.

Main Results:

• Successfully reconstructed traction forces from substrate deformations on non-planar surfaces.
• Demonstrated the feasibility of the developed workflow through data simulations and experimental application.
• Cardiac myofibroblasts exhibited alignment of cellular shape and force exertion along the substrate's long axis.

Conclusions:

• The new workflow enables accurate measurement of cell traction forces on complex, non-planar substrates.
• Cardiac myofibroblasts display anisotropic force generation and morphological alignment in response to wavy microenvironments.
• This method advances the study of cell-environment interactions in physiologically relevant, non-planar geometries.