Comparative Cytocompatibility and Morphological Assessment of Silver Nanoparticle Formulations in Human Dental Pulp Stem Cells

Objectives: This in vitro study evaluated the cytocompatibility and cellular response of human dental pulp stem cells (hDPSCs) exposed to two experimental polyethyleneimine/polyvinylpyrrolidone-stabilized silver nanoparticle formulations, MG-85 and MG-89. Methods: hDPSCs isolated from human third molars were treated with serial concentrations of both formulations. Cell metabolic activity and half-maximal inhibitory concentration (IC50) were assessed using the MTT assay. Wound closure was evaluated by wound-healing assay, while cytoskeletal organization and nuclear morphology were examined by phalloidin/DAPI fluorescence microscopy. Apoptosis/necrosis and intracellular reactive oxygen species production were analyzed by flow cytometry using Annexin V-FITC/7-AAD and CM-H2DCFDA, respectively. IL-6 release and IL-8 release were quantified by ELISA. Results: Both formulations induced concentration-dependent biological effects in hDPSCs. MG-89 showed a higher IC50 than MG-85 and preserved metabolic activity, wound closure, cytoskeletal organization, and nuclear morphology more effectively at low concentrations. At higher concentrations, both formulations impaired wound closure and altered cellular morphology, although these effects were more pronounced for MG-85. Flow cytometry showed increased apoptotic/necrotic populations at higher concentrations, particularly after MG-85 exposure. MG-85 also induced greater intracellular ROS production and higher IL-6/IL-8 release than MG-89. Conclusions: Within the limitations of this direct-exposure in vitro model, MG-89 exhibited a more favorable cytocompatibility profile than MG-85 in hDPSCs, particularly at low concentrations. These findings support the use of microscopy-based and multiparametric cellular assays for preclinical screening of AgNP-containing dental materials.