Pentoxifylline and tocopherol treatment improved the cortical bone quality and quantity on irradiated rodent model: A micro-CT and immunohistochemical study

Osteoradionecrosis;pentoxifylline;tocopherol;micro-CT;cortical bone;617.6

Nguyen Thi Hoang Truc치의학대학원 치의과학과 ;

University:서울대학교 대학원

关键词: Osteoradionecrosis;    pentoxifylline;    tocopherol;    micro-CT;    cortical bone;    617.6;   

Others  :  http://s-space.snu.ac.kr/bitstream/10371/161686/1/000000157864.pdf

美国|英语

来源: Seoul National University Open Repository

【 摘 要 】

IntroductionThe use of radiotherapy (RT) in head and neck malignancies treatment includes primary therapy, RT as adjuvant to surgery and RT in combination with chemotherapy or as palliative treatment for late stage and unresectable tumors. With recent advances in radiation technique, the undesired effects of irradiation were minimized. However, patients still suffer from reactions of the mucosa, jaw bone or salivary glands, of which one specific adverse effect is osteoradionecrosis (ORN) of the mandible. Pentoxifylline and tocopherol together work as potent antifibrotic agents, which are believed to have the effect of reducing the chronic fibrosis and induce bone healing in ORN. This combination may provide an adjuvant to surgical treatment or an alternative noninvasive treatment for ORN. The study was designed to assess the improvement of cortical bone quality and quantity on irradiated animal model treated with pentoxifylline and tocopherol using a novel micro-CT paradigm.Materials and methodsForty-eight 8-week-old male Sprague-Dawley rats (OrientBio Inc., Seongnam, Korea) with an average body weight of 369.6g were used in this study. Rats were randomly divided into irradiated group (n = 40) and non-irradiated control group (n = 8). In irradiated group, animals were divided into 4 subgroups according to treatment, including PTX + TP (pentoxifylline and tocopherol), PTX (pentoxifylline), TP (tocopherol), and NS (normal saline). Medicine was administrated until the end of the study. Three weeks after irradiation, mandibular posterior teeth were extracted. Animals were sacrificed 7 weeks after irradiation and 4 weeks after extraction. Cortical bone quality and quantity were analyzed using micro-CT and histological evaluation. Alveolar bone height (ABH) and cortical bone thickness (CBT) were compared between non-irradiation control group (C) and irradiated, normal saline administrated group (NS). ABH and CBT were also compared between irradiated groups with different medicine administrated. Cortical bone defect was evaluated on 3D reconstructed images.Results1. Micro-CT analysesBoth ABH and CBT results in group NS were significantly lower than those in non-irradiation group. The ABH and CBT of PTX + TP administrated group were significantly higher than other groups. The ABH and CBT of PTX and TP groups did not differed significantly. The CBT of PTX group was significantly higher than normal saline group (p < 0.05).In all irradiated groups, alveolar bone loss in the lingual side (ΔHL) results were significantly higher than alveolar bone loss in the buccal side (ΔHB). In addition, on buccal side, ΔHB of PTX + TP group was significantly lower compare to PTX group and NS group. On the lingual side, ΔHL of NS group was significantly higher than ΔHL of PTX and PTX + TP group (p < 0.05).In the irradiated group, cortical bone volume (Ct.BV) and total cortical bone surface (Ct.S) of PTX + TP group was significantly higher than which of PTX, TP and NS groups. Average cortical bone thickness (Ct.Th) of PTX + TP group was significantly higher than NS group. The total pore volume (PoV) of 4 groups did not differ significantly. However, total pore volume rate (PoV%) in PTX + TP group was significantly lower than which in PTX and NS groups, and did not significantly differ to TP group (p < 0.05).2. Three-dimensional (3D) reconstructed images evaluationIn all four irradiated groups, observed defective state of lingual walls were more severe than defective state of buccal walls. Also, defective state of PTX + TP group was lower than PTX, TP and NS groups. The 3D reconstructed images were also used to evaluate the correlation between cortical bone defect and cancellous bone defect at the extracted sites. In non-irradiated group, bone healing occurred and the extracted socket was filled with new formed cancellous bone, surrounding by healthy cortical bone walls. In irradiated groups, the non-healing wound and bone necrosis were observed. In addition, there was an inadequacy in the residual volume of cortical bone and cancellous bone. 3. Histological and immunohistochemical analysesWe observed empty lacunae with loss of nuclei in irradiated groups, especially in NS group. Viable blood vessels within Haversian canals can be observed in PTX + TP group, and a small amount in PTX group. In TP and NS group, the unviable blood vessels within Haversian canals were dominated. CD31 (PECAM) staining was used for evaluation of microvessel density (MVD). MVD of PTX + TP group was significantly higher than which of PTX, PT and normal saline groups (p < 0.05). Osteocalcin (OC) staining was used for evaluation of osteocyte within cortical bone. Number of OC+ osteocyte in NS group was significantly lower than other three groups. Number of OC+ osteocytes in PTX + TP, PTX and TP groups did not differ significantly (p < 0.05). The expression of TNF-α and TGF-β1 was relatively lower in group taking PTX +TP. The other markers including IL-6, ALP did not show significant difference.ConclusionFrom the results our study, cortical bone has proven to play an important role in the evaluation and prognosis of ORN. The combination of PTX and TP has improving effect on the cortical bone quality and quantity, resulting in a regression of the disease and can be a reliable treatment protocol or used for early ORN prevention in particular susceptible patients.