Effect of zoledronic acid on jaw bone marrow mesenchymal stem cells in mice with bisphosphonate-related osteonecrosis of the jaw

Abstract

BACKGROUND: Bisphosphonates, as the core drugs of anti-bone resorption therapy, are widely used in the treatment of metabolic bone diseases. However, long-term use can cause the complications of bisphosphonate related osteonecrosis of the jaw. The traditional pathogenesis focuses on the inhibitory effect of bisphosphonates on osteoclasts, but it is difficult to fully explain the pathological development of osteonecrosis. Compared with the relatively mature osteoclast research, there are fewer reports on the effects of bisphosphonates on the biological characteristics and functions of osteoblast-related cells, and there are differences between some reports. This difference may be due to the experimental system, drug concentration and cell source, highlighting the necessity of conducting systematic and standardized research. OBJECTIVE: To investigate the effect of the third-generation bisphosphonate-zoledronic acid commonly used in clinical practice on the healing of tooth extraction sockets and the proliferation, migration and osteogenic differentiation of bone marrow mesenchymal stem cells derived from the jaw in mice. METHODS: Sixteen male C57BL/6J mice were randomly divided into control and experimental groups. The experimental group received intraperitoneal injection of zoledronic acid combined with subcutaneous injection of dexamethasone, while the control group received an equal volume of PBS. After 2 weeks of injection, the left maxillary first molars of all mice were extracted, and after another 2 weeks of injection, the mice were sacrificed. The healing of extraction sockets was evaluated by gross observation, Micro CT imaging and three-dimensional reconstruction, and hematoxylin-eosin staining. Jaw bone marrow mesenchymal stem cells were isolated and cultured from both groups. After normal culture and osteogenic induction, cell proliferation, migration, and osteogenic differentiation were assessed by CCK-8 assay, qPCR, Western blot, alkaline phosphatase staining, and alizarin red staining. RESULTS AND CONCLUSION: Compared with the control group, the experimental group showed poor healing of extraction sockets with more inflammatory cell infiltration. The proliferation and migration abilities of jaw bone marrow mesenchymal stem cells were significantly inhibited in the experimental group (P < 0.05). Alkaline phosphatase staining was weaker, calcium nodule formation was reduced, and the expression of osteogenic markers (alkaline phosphatase, integrin-binding sialoprotein, collagen type I alpha 1 chain, Runt-related transcription factor 2) was downregulated in the experimental group (P < 0.05). These results indicate that zoledronic acid can adversely affect extraction socket healing, possibly by inhibiting the proliferation, migration, and osteogenic differentiation of jaw bone marrow mesenchymal stem cells.

1. Introduction

Bisphosphonates are a class of synthetic drugs that have emerged in recent years, divided into nitrogen-containing and non-nitrogen-containing types. They primarily treat metabolic bone diseases such as osteoporosis and multiple myeloma by inhibiting osteoclast activity and function [1-5]. However, bisphosphonate-related osteonecrosis of the jaw (BRONJ) has attracted widespread attention in recent years. Since MARX [6] first reported BRONJ in 2003, the number of case reports on this disease has increased annually [7-9]. Currently, approximately 4 million patients in China receive bisphosphonate therapy each year, with a global annual prescription volume of 71 million. The cumulative incidence of BRONJ ranges from 0.8% to 12%, with higher risk in intravenous administration [10].

BRONJ often occurs after invasive procedures such as tooth extraction and dental implant placement, manifesting as mucosal ulceration, pain, infection, and even bone exposure and pathological fractures. There is currently no recognized standard treatment, which seriously affects patients' physical and mental health and quality of life [11-13]. Regarding the pathogenesis of BRONJ, various hypotheses such as bone metabolic disorders and microbial infection have been proposed, but the exact mechanism has not been fully elucidated [14-18]. Although bone metabolic disorders are considered one of the important pathogenic mechanisms, existing studies cannot prove its universality across different patient populations. Additionally, the microbial infection hypothesis has gained some support, suggesting that oral microorganisms may trigger local inflammatory responses, contributing to the disease process.