Zoledronic acid and ibandronate-induced nephrotoxicity in 2D and 3D proximal tubule cells derived from human and rat.

Drug-induced proximal tubule (PT) injury remains a serious safety concern throughout drug development. Traditional in vitro 2-dimensional (2D) and preclinical in vivo models often fail to predict drug-related injuries presented in clinical trials. Various 3-dimensional (3D) microphysiological systems (MPSs) have been developed to mimic physiologically relevant properties, enabling them to be more predictive toward nephrotoxicity. To explore the capabilities of an MPS across species, we compared cytotoxicity in hRPTEC/TERT1s and rat primary proximal tubular epithelial cells (rPPTECs) following exposure to zoledronic acid and ibandronate (62.5-500 µM), and antibiotic polymyxin B (PMB) (50 and 250 µM, respectively). For comparison, we investigated cytotoxicity using 2D cultured hRPTEC/TERT1s and rPPTECs following exposure to the same drugs, including overlapping concentrations, as their 3D counterparts. Regardless of the in vitro model, bisphosphonate-exposed rPPTECs exhibited cytotoxicity quicker than hRPTEC/TERT1s. PMB was less sensitive toward nephrotoxicity in rPPTECs than hRPTEC/TERT1s, demonstrating differences in species sensitivity within both 3D and 2D models. Generally, 2D cultured cells experienced faster drug-induced cytotoxicity compared to the MPSs, suggesting that MPSs can be advantageous for longer-term drug-exposure studies, if warranted. Furthermore, ibandronate-exposed hRPTEC/TERT1s and rPPTECs produced higher levels of inflammatory and kidney injury biomarkers compared to zoledronic acid, indicating that ibandronate induces acute kidney injury, but also a potential protective response since ibandronate is less toxic than zoledronic acid. Our study suggests that the MPS model can be used for preclinical screening of compounds prior to animal studies and human clinical trials.

Impact of PRP and PRF on Viability of Zoledronic Acid Treated Osteoblasts in 2D and 3D Cell Culture.

BACKGROUND/AIM: Zoledronic acid (ZA) treatment of in vitro cultured osteoblasts (OB) results in reduction in viability, proliferation and differentiation. These effects are slightly attenuated when platelets-rich fibrin and plasma (PRF and PRP) are added. However, it is still unknown whether application of PRP/PRF on ZA-treated OB in a 3D-environment would influence the viability in relation to 2D-cultivation. MATERIALS AND METHODS: Non-treated and ZA-treated OB were cultivated in 2D conditions or seeded in a 3D collagen scaffold with and without PRP/PRF. MTT test was carried out after 5 days of colonization. 4,6-diamidino-2'-phenylindole, dihydrochloride (DAPI)-staining was performed in OB grown in 3D scaffolds to ensure spatial distribution of OB. RESULTS: ZA led to a significant reduction in cell viability compared to the control group. Addition of either PRF or PRP to the 3D colonized and ZA-treated OB significantly enhanced their survival and viability in relation to 2D monolayer cultivation. CONCLUSION: The use of 3D-scaffolds has a positive effect on OB viability, and stimulation by PRF and PRP may provide a therapeutic approach to transfer these results into clinical routine for the treatment of patients with bisphosphonate related osteonecrosis of the jaw (BR-ONJ).

Role of cytochrome P450 2C8 genetic polymorphism and epoxygenase uncoupling in periodontal remodelling affecting orthodontic treatment.

In genome-wide association studies, the CYP2C8 gene locus has been reported to be associated with bisphosphonate-related osteonecrosis of the jaw, a severe devastating side effect of antiresorptive bone treatment. The aim of this study was to elucidate the putative pathomechanism explaining the association between the genetic polymorphism with the alleles CYP2C8*2 and *3 causing low CYP2C8 activity, and disturbed periodontal remodelling in periodontal fibroblasts cultured from patients undergoing orthodontic treatment. CYP2C8 activity, enzyme expression and substrate metabolism were detected in human periodontal fibroblast cultures. Zoledronic acid caused enhanced reactive oxygen species (ROS) production in periodontal fibroblasts, which was enhanced by arachidonic acid as inflammatory signal. Enhanced bisphosphonate-induced uncoupling of the CYP2C8 enzyme was detected in the variant allele (CYP2C8*3) with the result of increased H2 O2 production and lowered substrate oxidation. Conversely, substrate (amodiaquine) addition led to decreased H2 O2 production in isolated CYP2C8 enzymes, but in CYP2C8*3 enzyme, increased H2 O2 was still detected, especially in presence of arachidonic acid. CYP2C8 variants leading to decreased enzyme activity in substrate oxidation may enhance ROS production by reaction uncoupling, and thus, contribute to difficulties in orthodontic treatment and the risk of side effects of antiresorptive drugs.

Suppression of Bone Necrosis around Tooth Extraction Socket in a MRONJ-like Mouse Model by E-rhBMP-2 Containing Artificial Bone Graft Administration.

Medication-related osteonecrosis of the jaw (MRONJ) is related to impaired bone healing conditions in the maxillomandibular bone region as a complication of bisphosphonate intake. Although there are several hypotheses for the onset of MRONJ symptoms, one of the possible causes is the inhibition of bone turnover and blood supply leading to bone necrosis. The optimal treatment strategy for MRONJ has not been established either. BMP-2, a member of the TGF-ß superfamily, is well known for regulating bone remodeling and homeostasis prenatally and postnatally. Therefore, the objectives of this study were to evaluate whether cyclophosphamide/zoledronate (CY/ZA) induces necrosis of the bone surrounding the tooth extraction socket, and to examine the therapeutic potential of BMP-2 in combination with the hard osteoinductive biomaterial, ß-tricalcium phosphate (ß-TCP), in the prevention and treatment of alveolar bone loss around the tooth extraction socket in MRONJ-like mice models. First, CY/ZA was intraperitoneally administered for three weeks, and alveolar bone necrosis was evaluated before and after tooth extraction. Next, the effect of BMP-2/ß-TCP was investigated in both MRONJ-like prevention and treatment models. In the prevention model, CY/ZA was continuously administered for four weeks after BMP-2/ß-TCP transplantation. In the treatment model, CY/ZA administration was suspended after transplantation of BMP-2/ß-TCP. The results showed that CY/ZA induced a significant decrease in the number of empty lacunae, a sign of bone necrosis, in the alveolar bone around the tooth extraction socket after tooth extraction. Histological analysis showed a significant decrease in the necrotic alveolar bone around tooth extraction sockets in the BMP-2/ß-TCP transplantation group compared to the non-transplanted control group in both MRONJ-like prevention and treatment models. However, bone mineral density, determined by micro-CT analysis, was significantly higher in the BMP-2/ß-TCP transplanted group than in the control group in the prevention model only. These results clarified that alveolar bone necrosis around tooth extraction sockets can be induced after surgical intervention under CY/ZA administration. In addition, transplantation of BMP-2/ß-TCP reduced the necrotic alveolar bone around the tooth extraction socket. Therefore, a combination of BMP-2/ß-TCP could be an alternative approach for both prevention and treatment of MRONJ-like symptoms.

Sonic hedgehog signaling is associated with resistance to zoledronic acid in CD133high/CD44high prostate cancer stem cells.

Cancer stem cells (CSCs) are a unique population that has been linked to drug resistance and metastasis and recurrence of prostate cancer. The sonic hedgehog (SHH) signal regulates stem cells in normal prostate epithelium by affecting cell behavior, survival, proliferation, and maintenance. Aberrant SHH pathway activation leads to an unsuitable expansion of stem cell lineages in the prostate epithelium and the transformation of prostate CSCs (PCSCs). Zoledronic acid (ZOL), one of the third-generation bisphosphonates, effectively prevented bone metastasis and treated advanced prostate cancer despite androgen deprivation therapy. Despite strong evidence for the involvement of the SHH in human PCSCs survival and drug resistance, the roles of SHH in the PCSCs-related resistance to ZOL remain to be fully elucidated. The present study aimed to investigate the role of the SHH pathway in ZOL resistance of PCSCs in 2D and three 3D cell culture conditions. For this purpose, we isolated CD133high/ CD44high PCSCs using a flow cytometer. Following ZOL treatment, mRNA and protein expressions of the components of the SHH signaling pathway in PCSCs and non-CSCs were analyzed using qRT-PCR and Immunofluorescence staining, respectively. Our finding suggested that SHH signaling may be activated by different mechanisms that lead to avoidance of the inhibition effect of ZOL. Thereby, SHH pathways may be associated with the resistance to ZOL developed by prostate CSCs. Inhibition of CSCs-related SHH signaling along with ZOL treatment should be considered to achieve improvement in survival or delayed treatment failure and prevention of the CSCs-related drug resistance.

Bisphosphonate-related osteonecrosis induced change in alveolar bone architecture in rats with participation of Wnt signaling.

OBJECTIVE: This work aimed to study the role of inflammation in medication-related osteonecrosis of the jaw (MRONJ) in rats with focus on Wnt signaling. METHODS: A total of 36 female Wistar rats (12 weeks ± 200 g) were divided into 2 groups (n = 6) in 3 experiments: saline (SAL) and zoledronic acid (ZOL). For MRONJ induction, rats received 0.1 mg/kg of ZOL (ip) 3×/week for 9 weeks. Animals from the SAL group received 0.1 mg/kg of 0.9% SAL, ip 3×/week for 9 weeks. On the 8th week, 3 left upper molars were extracted, and on the 11th week, they were euthanized. Maxillae were evaluated by macroscopic and histopathological analyses; scanning electron microscopy (SEM); immunohistochemistry for DKK-1, Wnt 10b, and caspase-3; and Raman spectrometry. Gingiva was also collected for TNF-α e IL-1ß quantification. RESULTS: Bone necrosis was confirmed by healing impairment, reduced number of viable osteocytes, increased caspase-3 immunoexpression, and increased number of empty lacunae (p < 0.05). ZOL enhanced inflammation and increased gingival levels of IL-1ß and TNF-α (p < 0.05). Irregular indentations were seen on bone after ZOL administration. Bone necrosis was marked by reduced amount of total and type I collagen. ZOL reduced the mineral/matrix ratio and increased carbonate/phosphate ratio. It was observed a significant reduction on Wnt10b and beta-catenin immunolabeling in the bone tissue of ZOL group. CONCLUSION: In summary, MRONJ model caused bone necrosis due to intense inflammation. Wnt signaling seems to play an important role in this process. CLINICAL RELEVANCE: New therapeutic strategies focusing on Wnt pathway can provide an interesting approach for future treatments.

Zoledronate promotes inflammatory cytokine expression in human CD14-positive monocytes among peripheral mononuclear cells in the presence of γδ T cells.

Bisphosphonates distributed to bone exert toxic effects specifically towards osteoclasts. On the other hand, intravenous administration of a nitrogen-containing bisphosphonate (N-BP) such as zoledronate induces acute-phase reactions (APRs), including influenza-like fever 1 day later, indicating an interaction with immunocompetent cells circulating blood. Although it has been reported that activation of γδ T cells is pivotal to induce an APR following treatment with zoledronate, downstream events, including the production of inflammatory cytokines after activation of γδ T cells, remain obscure. We investigated the effects of zoledronate on inflammatory cytokine expression in human peripheral blood mononuclear cells (PBMCs) in vitro. While zoledronate induced mRNA expressions of tumour necrosis factor-α (TNF-α), interleukin (IL)-1ß, IL-6 and interferon-γ (IFN-γ) in PBMC, depletion of γδ T cells abolished that zoledronate-induced expression of those cytokines, indicating the necessity of γδ T cells for expression induction by zoledronate. However, which types of cells were responsible for the production of those cytokines in blood remained unclear. As it is generally accepted that monocytes and macrophages are primary sources of inflammatory cytokines, CD14+ cells from PBMC were exposed to zoledronate in the presence of PBMC, which resulted in induced expression of mRNAs for IL-1ß, IL-6 and IFN-γ, but not for TNF-α. These results indicate that CD14+ cells are responsible, at least in part, for the production of IL-1ß, IL-6 and IFN-γ in blood exposed to zoledronate. This suggests that CD14+ cells play an essential role in the occurrence of APRs following N-BP administration.

Avaliação da ozonioterapia no tratamento da osteonecrose induzida por zoledronato em ratas senis / Evaluation of ozone therapy in the treatment of zoledronate-induced osteonecrosis in senile rats

A ozonioterapia vem se demonstrando uma ferramenta promissora na prevenção de infecções e no auxílio da reparação tecidual, conciliando com os desafios no tratamento da osteonecrose dos maxilares induzida por medicamentos (ONM-M), este projeto objetiva analisar os efeitos da ozonioterapia, em 55 ratas senis (18 meses), entre 300-350g, induzidas a osteonecrose via medicamentosa (Zoledronato 100µg/kg), após exodontia do primeiro molar inferior. Os animais foram divididos em 4 grupos equitativos (10 ratas por grupo), o primeiro grupo SAL, recebeu aplicações de soro fisiológico por 7 semanas, grupo SAL + OZ recebeu aplicações de soro fisiológico por 7 semanas e o tratamento com a ozonioterapia (0,7mg/kg) a cada 2 dias por 28 dias, o grupo ZOL recebeu aplicações de zoledronato (100µg/kg) por 7 semanas e por último o grupo ZOL + OZ recebeu também aplicações de zoledronato no mesmo protocolo e foi tratado com a ozonioterapia (0,7mg/kg) a cada 2 dias por 28 dias. Todos as ratas receberam a antibioticoterapia (Cristacilina® 0,1ml/kg por dia) iniciando 3 dias antes do procedimento de extração, se estendendo até 4 dias de pós-operatório, passaram pela extração do molar na terceira semana de experimento e foram submetidas a eutanásia na sétima semana de experimento. Após a eutanásia as mandíbulas foram ressecadas, reduzidas e preparadas para as análises microtomográficas (caracterização óssea do osso senil (MCT0) e após terapia com zoledronato (MCT1ZOL) contra seu par controle (MCT1SAL), parâmetros volumétricos (Bv,Bv.Tv,Tb.Th,Tb.N,Tb.Sp,Po.Tot) dos grupos experimentais), histométricas (porcentagem de osso neoformado e porcentagem de osso não vital) e imunoistoquímicas (expressão de TNFa, IL-1b, VEGF, OCN e TRAP). Os resultados da caracterização óssea não apresentaram diferença quando comparado os grupos experimentais (p> 0,05), possivelmente devido ao pouco tempo decorrido na terapia com zoledronato. Os demais resultados comparando os grupos experimentais mostrou com diferenças estatisticamente significativas (p< 0,05) uma característica de osso vítreo, denso, sem vitalidade, pobre em vascularização, com elevados valores para marcadores de inflamação, traduzindo isso em osteonecrose dos maxilares relacionada com a medicação, destoando principalmente do grupo controle SAL, que apresentou melhora na reparação alveolar e características de osso vital e vascularizado. A ozonioterapia (ZOL+OZ, SAL+OZ) apresentou valores significantes estatisticamente quando comparado ao grupo sem tratamento, traduzindo em melhora na vascularização do tecido ósseo, em melhora reparacional do alvéolo, modulação da inflamação local e o aparecimento/manutenção de células osteoblásticas ativas (p< 0,05). Mostrando-se uma terapia viável no controle/tratamento da osteonecrose dos maxilares relacionado com medicamentos(AU)

Ozone therapy has been shown to be a promising tool in the prevention of infections and in the aid of tissue repair, reconciling with the challenges in the treatment of medication-induced jaw osteonecrosis (ONM-M), this project aims to analyze the effects of ozone therapy in 55 rats senile (18 months), between 300-350g, induced to osteonecrosis via medication (Zoledronate 100µg / kg), after extraction of the lower first molar. The animals were divided into 4 equitable groups (ten rats per group), the first SAL group, received saline applications for 7 weeks, SAL + OZ group received saline applications for 7 weeks and ozone therapy (0, 7mg / kg) every 2 days for 28 days, the ZOL group received applications of zoledronate (100µg / kg) for 7 weeks and lastly the ZOL + OZ group also received applications of zoledronate in the same protocol and was treated with ozone therapy (0.7mg / kg) every 2 days for 28 days. All rats received antibiotic therapy (Cristacilina® 0.1ml / kg per day) starting 3 days before the extraction procedure, extending up to 4 days after the operation, underwent molar extraction in the third week of the experiment and were submitted to euthanasia in the seventh week of experiment. After euthanasia, the mandibles were resected, reduced and prepared for microtomographic analysis (bone characterization of senile bone (MCT0) and after therapy with zoledronate (MCT1ZOL) against its control pair (MCT1SAL), volumetric parameters (Bv, Bv.Tv, Tb .Th, Tb.N, Tb.Sp, Po.Tot) of the experimental groups), histometric (percentage of newly formed bone and percentage of non-vital bone) and immunohistochemistry (expression of TNFa, IL-1b, VEGF, OCN and TRAP) . The results of bone characterization did not show any difference when comparing the experimental groups (P> 0.05), possibly due to the short time elapsed in zoledronate therapy. The other results comparing the experimental groups showed with statistically significant differences (P < 0.05) a characteristic of vitreous bone, dense, without vitality, poor in vascularization, with high values for inflammation markers, translating this into a related jaw osteonecrosis with medication, disagreeing mainly with the SAL control group, which showed improvement in alveolar repair and characteristics of a vital and vascularized bone. Ozone therapy (ZOL + OZ, SAL + OZ) showed statistically significant values when compared to the untreated group, translating into an improvement in bone tissue vascularization, a reparational improvement of the alveolus, modulation of local inflammation and the appearance/maintenance of cells active osteoblasts (P < 0.05). Showing to be a viable therapy in the control/treatment of osteonecrosis of the jaws related to drugs(AU)

Systemic administration of quality- and quantity-controlled PBMNCs reduces bisphosphonate-related osteonecrosis of jaw-like lesions in mice.

BACKGROUND: Definitive treatment strategies for bisphosphonate-related osteonecrosis of the jaw (BRONJ) have not been developed. Cell-based therapy is an attractive treatment method for intractable diseases in the medical and dental fields; however, approval has been challenging in dentistry. Recently, we developed quality- and quantity (QQ)-controlled peripheral blood mononuclear cells (PBMNCs) that have anti-inflammatory and pro-angiogenesis effects. The aim of this study was to investigate the effects of QQ-controlled PBMNC transplantation on BRONJ-like lesions in mice. METHODS: To create high-prevalence BRONJ-like lesions, cyclophosphamide (CY) and zoledronate (ZA) were used with tooth extraction. Drug treatment was performed for 5 weeks. QQ-controlled PBMNC transplantation was performed immediately following tooth extraction of both maxillary first molars at 3 weeks after drug administration. Mice were euthanized at 2 weeks post-extraction. Histomorphometric and immunohistochemical analyses, microcomputed tomography assessment, and quantitative polymerase chain reaction evaluation were conducted using maxillae and long bones. RESULTS: ZA effects on long bones were noted, regardless of CY. Severely inhibited osseous and soft tissue wound healing of tooth extraction sockets was induced by CY/ZA combination therapy, which was diagnosed as BRONJ-like lesions. QQ-controlled PBMNC transplantation reduced BRONJ-like lesions by improving soft tissue healing with increased M1 and M2 macrophages and enhanced neovascularization in the connective tissue of tooth extraction sockets. QQ-controlled PBMNC transplantation also reduced inflammation by decreasing polymorphonuclear cells and TNF-α expression in the tooth extraction sockets. Additionally, QQ-controlled PBMNC transplantation partially improved osseous healing of tooth extraction sockets. Interestingly, only 20,000 QQ-controlled PBMNCs per mouse induced these transplantation effects. QQ-controlled PBMNC transplantation did not affect the systemic microenvironment. CONCLUSIONS: Our findings suggest that transplantation of a small amount of QQ-controlled PBMNCs may become novel therapeutic or prevention strategies for BRONJ without any adverse side effects.

Characterization of urinary biomarkers and their relevant mechanisms of zoledronate-induced nephrotoxicity using rats and HK-2 cells.

The aim of this study was to identify biomarkers of zoledronate-induced nephrotoxicity and to further characterize the mechanisms underlying this process by analyzing urinary metabolites. Twenty-four rats were randomly divided into four groups containing four (two control groups) or eight rats (two zoledronate groups) per group. The rats were injected intravenously with saline or zoledronate (3 mg/kg) singly (single, 3 weeks) or repeatedly eight times (3 weeks/time, 24 weeks). Serum blood urea nitrogen, serum creatinine, creatinine clearance, and kidney injury observed by hematoxylin and eosin and immunohistochemical staining were changed only in the repeated zoledronate group (3 mg/kg, 3 weeks/time, 24 weeks). Urinary levels of S-adenosylmethionine, S-adenosylhomocysteine, l-cystathionine, l-γ-glutamylcysteine, and glutathione related to glutathione metabolism and fumaric acid and succinic acid related to the tricarboxylic acid cycle in the zoledronate-treated group (3 mg/kg, 3 weeks/time, 24 weeks) were significantly lower than those in the control group, suggesting that zoledronate may cause cellular oxidative stress. Besides, urinary levels of uracil and uridine related to pyrimidine metabolism also decreased after zoledronate treatment (3 mg/kg, 3 weeks/time, 24 weeks), while the levels of hypoxanthine related to purine metabolism, histamine related to histamine metabolism, and several amino acids were significantly increased. Moreover, zoledronate-induced enhanced oxidative stress and histamine overproduction were confirmed by reactive oxygen species (ROS) and histamine measurement in a human proximal tubular cell line. Taken together, zoledronate-induced nephrotoxicity may be attributed to it inducing perturbations in glutathione biosynthesis and the tricarboxylic acid cycle, further causing ROS overproduction, oxidative stress, and cellular inflammation, thereby leading to nephrotoxicity.

Zoledronic acid induces cytogenetic toxicity in male germline cells of Swiss albino mice.

This study mainly focuses on the cytogenetic toxicity induction by zoledronic acid (ZA), a nitrogen containing bisphosphonate (N-BPs) in the male germline cells of Swiss albino mice. A single intraperitoneal exposure with three different doses of ZA (2, 4, and 8 mg/kg body weight), toxicity was assessed by analyzing spermatogonial metaphase chromosome aberrations at 24 h, aberrant primary spermatocytes at week 4, and abnormal spermatozoa at week 8 posttreatment. Cyclophosphamide (40 mg/kg) and 0.9% NaCl were used as positive and vehicle controls respectively in the study. The results showed that there was a significant induction in the number of chromosomal aberrations especially at two doses of ZA (4 and 8 mg/kg) after 24 h in the spermatogonial cells (p < 0.001) compared to vehicle control. The transmission genetic damages were noticed as aberrant spermatocytes with atypical bivalents (X-Y/autosomal asynapsis) at 4 mg/kg of ZA (p < 0.01) and at 8 mg/kg of ZA (p < 0.001) at week 4 posttreatment. A statistically significant higher number of abnormal spermatozoa (sperm) were also noticed at week 8 posttreatment of both at 4 and 8 mg/kg of ZA (p < 0.001). Hence, from these genotoxicity studies, it can be concluded that ZA is genotoxic in male germline cells and has the potential of transmitting the genotoxic effects from spermatogonial cells to sperm in male Swiss mice.

Epigallocatechin-3-gallate reduces damage to osteoblast-like cells treated with Zoledronic acid.

OBJECTIVE: analyze the effect of zoledronic acid (ZA) alone and in combination with epigallocatechin-3-gallate (EGCG) on human osteoblast cells. METHODS: SAOS-2 osteoblastic phenotype cell line treated with different doses (0.01-10 µM) of ZA or ZA + EGCG underwent cell viability, mineralization, collagen synthesis and cell migration tests. RESULTS: Micromolar (1 and 5 µM) doses of ZA reduced cell viability (p < 0.001), mineralization (p < 0.001), and collagen synthesis (p < 0.001), while nanomolar doses (0.1 µM) did not produce any effect. EGCG application partly reversed the inhibition produced by ZA, and even increased mineralization (p < 0.001). CONCLUSIONS: the data obtained shows that ZA at micromolar doses produces negative effects on osteoblast at all parameters measured, while at nanomolar levels ZA only affected cell migration and had no other effects on osteoblasts. The addition of EGCG partly reversed the effects produced by ZA, suggesting that this might be a promising preventative measure against BRONJ.

Bone mineralization and vascularization in bisphosphonate-related osteonecrosis of the jaw: an experimental study in the rat.

OBJECTIVES: Pathogenesis of bisphosphonate-related osteonecrosis of the jaws (BRONJ) is not fully explained. An antiangiogenic effect of bisphosphonates (BPs) or an altered bone quality have been advocated. The aims of the present study were to analyze alveolar mandibular vascularization and bone quality in rats with BRONJ. MATERIALS AND METHODS: Thirty-eight Sprague-Dawley rats were randomized into two groups: zoledronic acid (ZA), n = 27, and control (CTRL) n = 11. The ZA group received a weekly IV injection of ZA (100 µg/kg) during 10 weeks. The CTRL group received saline. After 6 weeks, extraction of the right mandibular molars was performed. Rats were sacrificed after 14 weeks. Microtomography characterized bone lesions and vascularization after injection of a radio-opaque material. Raman microspectroscopy evaluated bone mineralization. RESULTS: Fifty-five percent of ZA rats presented bone exposure and signs of BRONJ. None sign was found at the left hemimandible in the ZA group and in the CTRL group. Vascular density appeared significantly increased in the right hemimandibles of the CTRL group compared to the left hemimandibles. Vascularization was reduced in the ZA group. A significantly increased of the mineral-to-amide ratio was found in the alveolar bone of ZA rats by Raman microspectroscopy. CONCLUSIONS: In a rat model of BRONJ, microtomography evidenced osteonecrosis in BRONJ. Raman spectroscopy showed an increased mineralization. Vascularization after tooth extraction was impaired by ZA. CLINICAL RELEVANCE: Prolonged BP administration caused an increase in the mineralization and a quantitative reduction of the vascularization in the alveolar bone; both factors might be involved concomitantly in the BRONJ pathophysiology.