Foreign body response induced by tissue expander implantation.

Area of Science:

• Biomaterials Science
• Immunology
• Tissue Engineering

Background:

• The foreign body response (FBR) is a critical host reaction to implanted biomaterials, involving complex immune interactions.
• Dynamic changes in immune cells, inflammatory cytokines, and fibrous capsule formation during FBR require further elucidation.
• Understanding FBR is essential for the success of medical implants and tissue engineering scaffolds.

Purpose of the Study:

• To investigate the temporal dynamics of immune cell infiltration, cytokine expression, and fibrous capsule formation following subcutaneous tissue expander implantation.
• To elucidate the specific roles of macrophages and inflammatory pathways in mediating the FBR to tissue expanders.

Main Methods:

• Subcutaneous implantation of a tissue expander in a model system.
• Monitoring of immune cell infiltration (macrophages), collagen deposition, and fibroblast-to-myofibroblast transformation.
• Analysis of proinflammatory cytokine expression (TNF-α, IL-1β) and associated inflammatory pathways (NF-κB, JNK).

Main Results:

• Macrophages infiltrated the tissue and localized at the tissue-material interface from day 1 to 90 post-implantation.
• Fibrous capsule formation initiated around day 14, following macrophage decrease, with collagen deposition and myofibroblast differentiation.
• Persistent macrophages correlated with high expression of TNF-α and IL-1β, activating NF-κB and JNK pathways, thereby mediating FBR.

Conclusions:

• Macrophages are key players in the FBR to tissue expanders, orchestrating inflammation and capsule formation.
• The study elucidates the temporal sequence of FBR, from immune cell infiltration to fibrous capsule development.
• Targeting macrophage activity and inflammatory pathways presents a potential strategy for modulating FBR and improving biomaterial performance.