Actuation of Cell Layers in Three Dimensions

Area of Science:

• Biophysics
• Materials Science
• Tissue Engineering

Background:

• The mechanical properties and functionality of living tissues are influenced by the alignment of their constituent fibers and cells.
• Tissues can be analogized to nematic liquid crystal elastomers due to their ordered structures.

Purpose of the Study:

• To explore the analogy between cell sheets and nematic liquid crystal elastomers.
• To investigate the anisotropic contraction of fibroblast cell sheets upon detachment from patterned substrates.
• To demonstrate the potential for programming 3D tissue structures using 2D patterning principles.

Main Methods:

• Growing fibroblasts on 2D-patterned substrates with stripe patterns to induce alignment.
• Observing and quantifying cell sheet contraction upon detachment.
• Applying design principles from nematic elastomers to actuate 3D structures.
• Utilizing simulations to support experimental findings.

Main Results:

• Detached fibroblast sheets exhibit anisotropic contraction, with maximum contraction along the nematic director.
• Cell sheets behave similarly to nematic elastomers with a negative 2D Poisson ratio.
• Contraction is robust to drugs that affect cytoskeletal remodeling.
• Successfully actuated 3D structures in detached cell layers using elastomer design principles.

Conclusions:

• Cell sheets display nematic elastomer-like behavior, characterized by anisotropic contraction.
• 2D patterning can control the 3D shape of cell layers, offering a method for tissue programming.
• This study presents a proof of concept for programmable tissue actuation, opening avenues for tissue engineering applications.