Visualizing dynamic three-dimensional changes of human reticular dermal collagen under mechanical strain

Area of Science:

• Biomedical Engineering
• Dermatology
• Materials Science

Background:

• Managing large skin defects from burns or trauma necessitates understanding skin biomechanics.
• Previous research on skin's response to mechanical stress was limited to static conditions.
• Dynamic microstructural adaptations in skin under mechanical load remain largely unexplored.

Purpose of the Study:

• To investigate dynamic collagen rearrangement in human reticular dermis under mechanical deformation.
• To introduce and validate a novel method combining uniaxial stretch tests with fast second harmonic generation (SHG) imaging.

Main Methods:

• Utilized ex vivo human skin samples (abdomen, upper thigh).
• Applied uniaxial stretch tests while employing fast SHG imaging for real-time 2D and periodic 3D visualization.
• Quantified collagen alignment using orientation indices across different stress-strain curve stages.

Main Results:

• Observed significant variability in collagen alignment across skin samples.
• Demonstrated a marked increase in collagen alignment during the linear phase of the stress-strain response.
• Successfully visualized dynamic 3D reorganization and real-time 2D changes in dermal microstructure.

Conclusions:

• Fast SHG imaging during uniaxial extension is a viable and promising tool for studying skin biomechanics.
• The findings provide new insights into dynamic collagen behavior under mechanical stress.
• This technique can advance research on skin wound healing and tissue engineering.