Medication-related osteonecrosis of the jaws after tooth extraction in senescent female mice treated with zoledronic acid: Microtomographic, histological and immunohistochemical characterization

Abstract

Treatment with cumulative dosages of zoledronic acid (ZA) in elderly patients is a risk factor for the development of medication-related osteonecrosis of the jaws (MRONJ), mainly related to surgical triggers such as tooth extraction. However, animal models for the investigation and understanding of MRONJ pathophysiology in senescent and postmenopausal stages remains to be developed and characterized. The aim of this study was to analyze MRONJ development in senescent female mice treated with cumulative dosages of ZA. For this purpose, twenty 129/Sv female mice, 64 weeks old, were treated with 0.9% saline solution as control group (n = 10), and with ZA at 250μg/Kg (n = 10), once a week, starting 4 weeks before the upper right incisor extraction and until the end of the experimental time points (7 days and 21 days). At 7 and 21 days post-surgery, specimens were harvested for microCT, histological, birefringence and immunohistochemical analysis. Clinically, an incomplete epithelialization was observed in ZA group at 7 days and a delayed bone matrix mineralization and collagen maturation at 7 and 21 days compared to the controls. Controls revealed sockets filled with mature bone at 21 days as observed by microCT and birefringence, while ZA group presented delayed bone deposition at 7 and 21 days, as well increased leukocyte infiltration and blood clot at 7 days, and increased bone sequestrum and empty osteocyte lacunae at 21 days (p<0.05). Also, ZA group presented decreased quantity of TGFb+ and Runx-2+ cells at 7 days, and decreased quantity of TRAP+ osteoclasts compared to the control at 21 days (p<0.05).

Local delivery of hydrogel encapsulated vascular endothelial growth factor for the prevention of medication-related osteonecrosis of the jaw

“…This finding is supported by a previous study showing that ZA suppresses OCN levels in a rat MRONJ model, which could be counteracted by local application of autologous Platelet-Rich Plasma 59 . Furthermore, TRAP, an osteoclast activity marker known to be suppressed in MRONJ lesions 60 , 61 , showed a significant increase in gene expression after VEGF delivery (p = 0.0043). Similarly, when the expression of inflammatory genes was assessed, VEGF treatment resulted in much lower expression of IL-1β in comparison to gel-alone treated animals in the soft tissues.…”

“…Areas of osteonecrosis as evidenced histologically by regions of empty lacunae, were evaluated within the healing extraction sockets. Briefly, regions of > 500 μm 2 were examined 78 using the Aperio Imagescope software for bone sequestrations (of any size exhibiting empty lacunae) that is considered to be a hallmark of rodent MRONJ as reported by Biguetti et al previously 61 . The annotation tool on the Imagescope software was used to mark the area of osteonecrosis (µm 2 ), which was quantified and compared between the groups.…”

“…Intense leukocyte infiltration is typically found within areas of MRONJ in rodents 61 . Inflammatory component(s) around the sequestration on the histological sections were quantified in our study as described below.…”

Is the Bacterial Cellulose Membrane Feasible for Osteopromotive Property?

“…The data obtained in the analyses were transformed into absolute values, from pixels to square micrometers, to minimize the interference of the negative size difference. For comparison between the mean values obtained in the different experimental groups and periods, the data were subjected to initial statistical tests [12,29,30].…”

New Surgical Model for Bone–Muscle Injury Reveals Age and Gender-Related Healing Patterns in the 5 Lipoxygenase (5LO) Knockout Mouse

“…We conducted estrus cycle analysis (Toluine blue O vaginal smears) to determine postmenopausal stage in all aged female mice (50,51). All animal procedures were cared for in accordance with the CONCEA and following the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health (Institute of Laboratory Animal Resources (U.S.), as well as the ARRIVE guidelines recommendations (52). Experimental groups for bone-muscle surgical injury model were comprised of five animals per group/time point (7 and 14 days) and used for microtomography (microCT), histological, and immunohistochemical analysis.…”