High Glucose Concentrations Suppress the Proliferation of Human Periodontal Ligament Stem Cells and Their Differentiation Into Osteoblasts

Background: Diabetes mellitus (DM) is a major risk factor for periodontal disease and affects various cellular functions. Periodontal ligament stem cells (PDLSCs) play an important role in periodontal tissue regeneration; however, the effect of hyperglycemia on PDLSCs is unclear. The aim of this study is to investigate whether hyperglycemia affects periodontal tissue regeneration, using human PDLSCs and high-glucose medium as a model of DM. Methods: PDLSCs were obtained from healthy adult human mandibular third molars. Cell proliferation, osteoblastic differentiation, and proinflammatory cytokine expression were investigated by culturing PDLSCs in media supplemented with four different glucose concentrations representative of control patients (5.5 mM), patients with postprandial or controlled DM (8.0 mM), and patients with uncontrolled DM (12.0 and 24.0 mM). The molecular effects of hyperglycemia on PDLSC physiology were examined with a focus on the nuclear factor (NF)-(kappa B signaling pathway. The involvement of NF-kappa B was investigated with a specific NF-kappa B inhibitor in PDLSCs under hyperglycemic conditions. Results: High glucose levels inhibited PDLSC proliferation and differentiation into osteoblasts but induced NF-kappa B activation and subsequent interleukin (IL)-6 and IL-8 expression. Treatment with an NF-kappa B inhibitor rescued the defects in cell proliferation and osteoblastic differentiation and inhibited the IL-6 expression caused by the high-glucose environment. Conclusion: The results of this study demonstrate that hyperglycemia inhibits human PDLSC proliferation and osteoblastic differentiation.