Ozone saline solution counteracts bisphosphonates noxious effects in primary human gingival fibroblasts

Abstract

Background Bisphosphonates are effective antiresorptive agents frequently used in the treatment of different bone disorders, as osteoporosis, Paget’s disease and tumours that cause osteolysis. A major concern related to bisphosphonates therapy is represented by osteonecrosis of jaw, a serious, debilitating, and mostly, a therapy-resistant disease, reported as a frequent side effect of bisphosphonates. In the present study were proposed two approaches: 1) to verify the impact of four commercially available bisphosphonates, very frequently used as oral (Fosamax - F and Actonel - A) and injectable (Ossica - O and Zoledronic acid - Z) therapy on primary human gingival fibroblasts - HGF viability and 2) to evaluate the protective effect of an ozone saline solution on HGF cells pretreated with bisphosphonates. Methods Alamar blue cell viability assay was performed to assess the effect of test compounds (1.5; 2.5; 5 and 10 μM) on gingival fibroblasts viability after a 24 h interval. An ozone - O3 saline solution – 80 µg/mL was added to bisphosphonates pretreated fibroblasts for 24 h and cell viability and cell morphology changes were determined by the means of Alamar blue test and microscopic images. Results Fosamax and Actonel induced a significant reduction of HGF cells viability even at concentrations as low as 2.5 μM (82 and 79.33%) and changes in cells morphology (round and floating cells), effects that were reversed by O3 saline solution administration: an increased cell viability after F and A at 2.5 μM: 147.54 and 120.11%), no changes in cells morphology and an improved confluence. Ossica and Zoledronic acid exerted no cytotoxic effect. Conclusions In conclusion, in these experimental conditions, injectable bisphosphonates (O and Z) proved to be safe for HGF cells, whereas oral compounds (F and A) were cytotoxic even at low concentrations, effects that were counteracted by O3 saline solution administration. Based on these data, ozone saline solution might represent a therapeutic alternative for bisphosphonates noxious effects on oral mucosa cells.