Medication-related osteonecrosis of the jaw (MRONJ) is an adverse effect of bisphosphonate therapy which is characterised by the loss of overlying soft tissue and exposure of necrotic bone in the oral cavity1, affecting the quality of life of patients2. The lack of effective treatment approaches3 leads to the development of alternative therapies including platelet-rich fibrin (PRF) applications. Clinical studies have shown that PRF can improve the healing of MRONJ wounds, but the evidence is limited and the mechanisms of PRF on the healing process have yet to be explained. Thus, the aim of this in vitro study was to investigate the impact of PRF in the form of conditioned medium on oral keratinocyte activities in the presence of zoledronate (ZA), the most potent nitrogen-containing bisphosphonate.
Blood samples from healthy volunteers were taken and processed to obtain a liquid formulation of PRF (Liquid-PRF). Collected PRF was incubated with cell culture medium for 3 days at 37oC to prepare the conditioned medium (100%). Oral keratinocytes were treated with different conditioned medium derived from liquid-PRF or in combination with 10 µM ZA. To determine the role of PRF on the wound healing process, metabolic activity, proliferation and migration of keratinocytes were investigated.
We found that ZA decreased the metabolic activity and proliferation of oral keratinocytes after 72 hours. The addition of PRF-conditioned medium produced a slight increase in cell metabolism. Interestingly, treatment with the highest concentration (50%) of PRF-conditioned medium significantly increased the proliferation index of ZA-treated keratinocytes. At 24 hour, ZA inhibited keratinocyte migration across the gap, representing a clinical wound. All concentrations of PRF-conditioned medium produced a complete closure of the cell-free gap when compared to ZA-treatment.
These findings suggest that PRF could play a part in the healing process of ZA-induced toxicity by promoting cell migration and proliferation. Future work on the effects of PRF using 3D tissue models are required to confirm the potential bioactivity of PRF on the healing of soft tissue wounds in MRONJ patients.
1. Zafar, S. et al. J. Oral Pathol. Med. 43, 711–721 (2014).
2. Miksad, R. A. et al. Oncologist 16, 121–132 (2011).
3. Ruggiero, S. L. et al.. J. Oral Maxillofac. Surg. 72, 1938–1956 (2014).