Mesenchymal stem cell-derived apoptotic bodies alleviate alveolar bone destruction by regulating osteoclast differentiation and function

Abstract

Abstract Periodontitis is caused by an imbalance between bone formation and resorption that results in the loss of periodontal supporting tissue. Mesenchymal stem cells (MSCs) are essential for the periodontal regeneration. However, the hypoxic periodontal microenvironment will induce the MSCs apoptosis. Apoptotic bodies (ABs) are the major product of apoptotic cells and are gaining increased attention as potential mediators for periodontitis treatment, thus we investigated the effects of ABs from MSCs on periodontitis. Bone marrow mesenchymal stem cells (BMMSCs) were cultured under hypoxia for 72 h to simulate the periodontal hypoxic microenvironment, after which ABs were isolated using a multi-filtration system from the supernatant of BMMSCs. Transmission electron microscopy, diameter assessment and immunofluorescence were used to characterize ABs. We found that ABs inhibited osteoclast differentiation and alveolar bone resorption, miR-223-3p is highly enriched in ABs and critical for the therapeutic effects of ABs. Targetscan and luciferase activity results confirmed that ITGB1 was targeted by miR-223-3p, which interfered the function of osteoclasts. Additionally, DC-STAMP is one of the key regulators that mediates membrane infusion. ABs and pre-osteoclasts are highly expressed DC-STAMP on the membrane, which mediated the target engulf of ABs by pre-osteoclasts. ABs with knock-down of DC-STAMP (KO-ABs) failed to be engulfed by pre-osteoclasts. Collectively, BMMSC-derived ABs can be targeted engulfed by pre-osteoclast via DC-STAMP, rescued alveolar bone loss by transferring miR-223-3p to osteoclasts, which led to the attenuation of their differentiation and bone resorption. These results suggest that MSCs derived ABs are promising therapeutic agents for the treatment of periodontitis.