Fibrous nonlinear elasticity enables positive mechanical feedback between cells and ECMs

Area of Science:

• Biophysics
• Cell Biology
• Biomaterials Science

Background:

• Animal cells are supported by fibrous extracellular matrix (ECM) networks.
• Mechanical interactions between cells and the 3D ECM regulate cell functions like growth and migration.
• The physical mechanisms of cell interaction with fibrous 3D ECM remain largely unknown.

Purpose of the Study:

• To investigate the physical mechanisms governing cell interactions with 3D fibrous ECM.
• To measure single-cell traction forces in breast tumor cells within 3D collagen matrices.
• To understand the role of matrix microstructure and density in cellular mechanical responses.

Main Methods:

• Utilized single-cell traction force microscopy.
• Embedded breast tumor cells within 3D type I collagen matrices.
• Controlled collagen matrix microstructure and density to mimic tumor mechanical environments.

Main Results:

• Identified a positive mechanical feedback loop between cells and the ECM.
• Observed that cells pulling on collagen locally align and stiffen the matrix.
• Demonstrated that stiffer matrices enhance cell force generation and cell body stiffness.
• Found that cell force transmission distance increases with matrix strain-induced stiffening and fiber alignment.

Conclusions:

• The nonlinear elasticity of fibrous matrices is critical for regulating cell-ECM interactions in 3D.
• The uncovered cell force regulation principle may explain rapid mechanical tissue stiffening in diseases like cancer and fibrosis.