Substrate viscoelasticity affects human macrophage morphology and phagocytosis

Area of Science:

• Biomaterials Science
• Cell Biology
• Immunology

Background:

• Viscoelasticity, a time-dependent mechanical property, is crucial in living tissues.
• Engineered hydrogels mimic tissue viscoelasticity for cell culture applications.
• Existing research shows viscoelasticity affects adherent cell behavior, but its role in macrophage function is unexplored.

Purpose of the Study:

• To investigate the influence of substrate viscoelasticity on macrophage behavior and function.
• To determine if viscoelasticity acts as a biophysical regulator of macrophage activity.
• To explore the implications for designing immunomodulatory biomaterials.

Main Methods:

• Utilized a tunable polyacrylamide hydrogel system to create substrates with varying viscoelastic properties.
• Validated the hydrogel system using HS-5 fibroblasts to confirm known cellular responses.
• Cultured human THP-1 monocytes on viscoelastic hydrogels and induced differentiation into macrophages.

Main Results:

• Macrophage size and morphology were affected by substrate viscosity; macrophages became smaller and rounder on more viscous substrates.
• Phagocytic efficiency of macrophages decreased on more viscous polyacrylamide hydrogel substrates.
• The study successfully demonstrated viscoelasticity as a regulator of macrophage function.

Conclusions:

• Substrate viscoelasticity is a critical biophysical factor modulating macrophage behavior, including morphology and phagocytosis.
• These findings suggest that biomaterial viscoelasticity is a key design parameter for developing effective immunomodulatory materials.
• Understanding viscoelasticity's role in macrophage function has implications for inflammatory and fibrotic disease research.