Engineered Immunomodulatory Nanoparticles Inhibit Root Resorption and Ankylosis

Area of Science:

• Biomaterials Science
• Immunology
• Dental Research

Background:

• External root resorption after avulsion injury involves macrophage (Mϕ) differentiation into osteoclasts, regulated by periodontal fibroblasts (PDLF).
• Chitosan nanoparticles (CSNP) offer potential for therapeutic intervention in root resorption.

Purpose of the Study:

• To evaluate engineered chitosan nanoparticles (CSNP), dexamethasone-conjugated CSNP (CS-DEX), and Rose Bengal-functionalized CSNP (CSRB) for treating root resorption.
• To assess these materials in an in-vitro PDLF-Mϕ coculture model and an in-vivo delayed reimplantation model.

Main Methods:

• Utilized a direct coculture system of PDLF and Mϕ exposed to inflammatory stimuli and CSNP/CS-DEX.
• Assessed clastic differentiation via TRAP staining and immunofluorescence for Mϕ polarization, multinucleation, and cytokine profiles.
• Employed a rat delayed reimplantation model with root surface treatment using CS-DEX/CSRB, followed by histological and immunofluorescence analysis.

Main Results:

• CS-DEX significantly reduced TRAP+ multinucleated cells in vitro.
• CSNP/CS-DEX modulated Mϕ polarization markers (CD80, NFATc1, STAT6) and enhanced periostin expression.
• In vivo, CS-DEX and CSRB treatments substantially reduced root resorption and ankylosis, with favorable expression of key markers compared to controls.

Conclusions:

• Engineered CSNP, particularly CS-DEX and CSRB, effectively inhibit Mϕ differentiation into clastic cells in vitro.
• These biomaterials demonstrate significant potential in minimizing resorption and ankylosis in a delayed tooth reimplantation model.
• Functionalized CSNP represent promising root modification agents for enhancing healing after dental avulsion.