Abstract
Background
The onset mechanism for bisphosphonate‐related osteonecrosis of the jaw (BRONJ) has been reported, with a focus on bone remodeling, biofilm formation, and epithelial cell proliferation and migration. However, the involvement of stromal cells, especially fibroblasts, in the oral cavity is unclear. Therefore, this study was focused on how bisphosphonates (BPs) affect orthotopic periodontal ligament fibroblasts from the viewpoint of oxidative stress compared with ectopically obtained fibroblasts.
Methods
Normal human periodontal ligament fibroblasts (HPdLFs) and dermal fibroblasts (NHDFs) were used to gain insight into the functional differences in sensitivity and reactions to BPs. Cell growth assay, measurement of reactive oxygen species and nitric oxide production and wound‐healing assay in vitro were performed. Maxillary first molars were extracted in C57BL/6 mice and either bisphosphonate, N‐acetyl‐cysteine (NAC) and bisphosphonate or saline were administered.
Results
BP‐induced IC50 values were significantly lower in HPdLFs (30.6 µM) than in NHDFs (109.7 µM). BP resulted in an increase in reactive oxygen species (ROS), but not nitric oxide (NO) generation in HPdLFs. BPs also inhibited proliferation and migration of HPdLFs but not NHDFs, while the addition of a ROS inhibitor, NAC, reversed those inhibitions. A BRONJ mouse model in which BP was administered and then the tooth was extracted, impaired wound healing of the socket was observed. When NAC was administered before tooth extraction, wound healing was significantly improved.
Conclusions
These results suggest that BP causes fibroblasts obtained from the oral cavity but not from skin to generate ROS and that the subsequent ROS‐mediated inhibition of fibroblast growth and migration definitely delays wound healing, thereby contributing to BRONJ pathogenesis.
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https://aap.onlinelibrary.wiley.com/doi/abs/10.1002/JPER.19-0385?af=R
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