Metformin Carbon Dots for Promoting Periodontal Bone Regeneration via Activation of ERK/AMPK Pathway

The osteogenic potential of mesenchymal stem cells (MSCs) is severely impaired under persistent inflammation of periodontitis. A highly efficient way to promote or rescue osteogenic potential of MSCs under inflammation remains an unmet goal. Herein, metformin carbon dots (MCDs) with excellent biocompatibility are prepared from metformin hydrochloride and citric acid via a hydrothermal method. The MCDs can more effectively enhance the alkaline phosphatase (ALP) activity, calcium deposition nodules formation, expression of osteogenic genes and proteins in rat bone marrow mesenchymal stem cells (rBMSCs) than metformin under both inflammatory and normal conditions. Moreover, a novel pathway of extracellular signal-regulated kinases (ERK)/AMP-activated protein kinase (AMPK) signaling is involved in the MCDs-induced osteogenesis. In periodontitis rats, MCDs can effectively regenerate the lost alveolar bone, but not the metformin. Taken together, MCDs can be the promising candidate nanomaterial for periodontitis treatment. This work may provide a new pharmacological target of ERK/AMPK pathway for treating bone loss and also give additional insights into developing nanodrugs from the numerous medications.