Cargo-less Nanoparticles Prevent Bone Loss in Periodontitis and Peri-implantitis

Periodontal and peri-implant diseases are a significant public health problem worldwide, resulting in the destruction of the supporting bone. These bone defects can cause esthetic problems, increased relapse rate, and eventually tooth loss. The etiology of periodontal disease involves an influx of innate immune cells (neutrophils and monocytes) and upregulation of local inflammatory cytokines in the gingiva. Biodegradable polymeric nanoparticles are an inexpensive, safe, and effective means of preventing innate immune activation by bacterial biofilms. We therefore hypothesize that this technology is a potential means of managing periodontal disease. Polylactic acid (PLA) particles were fabricated using an oil-in-water emulsion and used as a therapy in ligature-induced periodontitis and peri-implantitis. Mice were treated daily with nanoparticles or saline control through intravenous injection for 5 or 7 d. Bone loss and quality were characterized using micro-computed tomography and histology, and immune cell infiltrate was characterized by flow cytometry and enzyme-linked immunosorbent assay. PLA particle therapy prevented bone loss in both periodontitis and peri-implantitis. Particle treatment was associated with decreased osteoclast activation. Flow cytometry showed particles were mainly taken up by macrophages and limited inflammatory monocyte recruitment to the ligature site. In vitro evaluation of particle therapy demonstrated the inhibition of toll-like receptor activation during particle treatment. These results extended to monocytes that had been presensitized by titania nanoparticles. Taken together, the results of these experiments demonstrated that cargo-less PLA particle therapy may be a safe, cost-effective therapy to manage inflammatory bone loss in periodontal disease.