Macrophage-Driven Biomaterial Degradation Depends on Scaffold Microarchitecture

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Cellular Biology

Background:

• In situ tissue engineering utilizes degradable scaffolds to promote tissue regeneration.
• Macrophage activity drives both tissue formation and scaffold degradation.
• Scaffold microarchitecture influences cellular interactions and degradation kinetics.

Purpose of the Study:

• To investigate how scaffold microarchitecture (fiber diameter and alignment) affects early macrophage-driven degradation.
• To elucidate the role of reactive oxygen species (ROS) and hydrolytic enzymes in this process.
• To determine if macrophage polarization (M1/M2) explains microarchitecture-dependent degradation.

Main Methods:

• Fabrication of electrospun poly-ε-caprolactone-bisurea (PCL-BU) scaffolds with varying fiber diameters (2 vs. 6 μm) and alignment (isotropic vs. anisotropic).
• Seeding scaffolds with THP-1 derived human macrophages and culturing in vitro for 4 or 8 days.
• Assessing scaffold degradation, ROS production (lipid peroxidation, NADPH oxidase gene expression), and macrophage polarization.

Main Results:

• Scaffold microarchitecture significantly influenced macrophage-induced degradation, particularly oxidative degradation.
• The 6 μm diameter anisotropic scaffolds showed the highest levels of ROS-induced degradation.
• Differences in degradation were not attributable to distinct M1 or M2 macrophage polarization, suggesting a direct microarchitectural effect.

Conclusions:

• Scaffold microarchitecture is a critical factor in modulating macrophage-driven degradation kinetics.
• Tailoring fiber diameter and alignment is essential for controlling in situ tissue engineering scaffold degradation.
• Understanding these interactions is key for designing effective biomaterials for tissue regeneration.