Endothelial Progenitor Cells inhibit jaw osteonecrosis in a rat model: A major adverse effect of bisphosphonate therapy

Tal Tamari,Ofri Doppelt,Lana Eskander-Hashoul,Rina Elimelech,Talia Cohen,Hadar Zigdon-Giladi,Gal Cohen

doi:10.1038/s41598-019-55383-5

Abstract

Medication-related osteonecrosis of the jaw (MRONJ) is a serious adverse effect of antiresorptive and antiangiogenic therapies. MRONJ is identified by chronic wounds in the oral mucosa associated with exposed necrotic bone. We hypothesized that zoledronic acid (ZOL) impairs keratinocyte and fibroblast function and reduces soft tissue vascularization; therefore, treating MRONJ with proangiogenic cells may benefit MRONJ patients. The effect of ZOL and dexamethasone (DEX) on gingival fibroblasts and keratinocytes was investigated. In-vitro, ZOL inhibited fibroblast and keratinocyte proliferation, delaying scratch healing. In-vivo, exposed bone was detected at tooth extraction sites, mainly in ZOL(+)/DEX(+) rats; and was associated with significantly decreased soft tissue vascularization, serum-VEGF, and tissue-VEGF. Local injection of early and late endothelial progenitor cells (EPCs) healed 13 of 14 MRONJ lesions compared with 2/7 lesions in the mesenchymal stem cells, and 2/6, in culture-medium group. The EPCs reduced necrotic bone area, increased serum and tissue VEGF levels. EPCs engraftment was minimal, suggesting their paracrine role in MRONJ healing. The EPC-conditioned medium improved scratch healing of keratinocytes and fibroblasts via VEGF pathway and elevated mRNA of VEGFA and collagen1A1. In conclusion, a novel MRONJ treatment with EPCs, increased vascularization and improved epithelial and fibroblast functions as well as cured the lesion.

Highlights

Medication-related osteonecrosis of the jaw (MRONJ) is a serious adverse effect of antiresorptive and antiangiogenic therapies
The effect of zoledronic acid (ZOL) and DEX on in-vitro wound healing was investigated in XTT and scratch wound assays using gingival fibroblasts (GF) and keratinocytes
Treatment with 10 μM ZOL or 10 μM ZOL (+)/DEX(+) significantly reduced GF and keratinocyte proliferation at 48 and 72 h (GF at 48 and 72 h, P ≤ 0.0001 compared to Dulbecco’s modified Eagle medium (DMEM); keratinocytes at 48 h P ≤ 0.03, at 72 h P ≤ 0.009 compared to DMEM; Fig. 1a)

Summary

Introduction

Medication-related osteonecrosis of the jaw (MRONJ) is a serious adverse effect of antiresorptive and antiangiogenic therapies. We hypothesized that zoledronic acid (ZOL) impairs keratinocyte and fibroblast function and reduces soft tissue vascularization; treating MRONJ with proangiogenic cells may benefit MRONJ patients. Sonis et al described a MRONJ rat model using subcutaneous injection of zoledronic acid (ZOL) and dexamethasone (DEX) coupled with tooth extraction[14]. In this study we investigated a cell-based therapy that utilized endothelial progenitor cells (EPCs) as a treatment modality for MRONJ in a rat model. We hypothesize that zoledronic acid (ZOL) and dexamethasone (DEX) interrupt normal soft tissue wound healing and exacerbate MRONJ. Our goal was to follow the effect of ZOL and DEX on the in-vitro wound healing of keratinocytes and fibroblasts, and to evaluate vascular alterations in the oral mucosa in a MRONJ rat model. We investigated the potential for human EPCs to cure MRONJ based on this model

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