Normal and pathologic tissue reactions to soft tissue gel fillers

Area of Science:

• Biomaterials Science
• Immunology
• Tissue Engineering

Background:

• Gels function as foreign bodies, eliciting host responses ranging from macrophage activity to intense fibrosis.
• Host reaction severity depends on gel composition, with polymer gels causing volume-dependent effects and combination gels triggering reactions to microparticles.

Purpose of the Study:

• To elucidate host tissue reactions to diverse gel types.
• To differentiate adverse reactions based on specific gel compositions.

Main Methods:

• Review of experimental and clinical studies over 6.5 years.
• Analysis of biopsies from adverse reaction cases.

Main Results:

• Hydrophilic polymer gels exhibit minimal fibrosis due to water exchange.
• Degradable gels are phagocytosed by macrophages; polyacrylamide gels are infiltrated by fibrous tissue.
• Most gels induce foreign-body reactions and fibrosis; hydrophilic gels are associated with bacterial infections, while others form fibrous granulomas.

Conclusions:

• Infectious nodules require antibiotic treatment.
• Fibrous granulomas necessitate treatment with steroids and antibiotics or surgical excision.