Effect of different doses of transforming growth factor-β1 on cartilage and subchondral bone in osteoarthritic temporomandibular joints

Transforming growth factor-beta (TGF-β) plays an important part in the repair of cartilage in osteoarthritis. It has been hypothesised that intra-articular injection of TGF-β₁ promotes repair of cartilage and protects the subchondral bone from damage in osteoarthritic temporomandibular joints (TMJs). We made bilateral partial perforations of the disc to induce osteoarthritic joints in 36 rabbits. TGF-β₁ 20, 40, or 80 ng were injected into the right joint, and vehicle alone was injected into the left joint. Four additional animals were used as normal controls. Microcomputed tomography was used to quantify the three-dimensional microarchitecture of subchondral bone, followed by assessment of the proteoglycan content. All joints treated with TGF-β₁ were covered by a layer of well-organised fibrocartilage, and had increased proteoglycan content and normal microarchitectural properties, whereas the joint treated by vehicle alone had typical osteoarthritis-related degradation of cartilage and sclerosis of subchondral bone. These results suggested that TGF-β₁ is an effective way of treating osteoarthritis of the TMJ.     

Effect of platelet-rich plasma on temporomandibular joint cartilage wound healing: Experimental study in rabbits

Purpose

The aim of the study is to evaluate the effect of platelet-rich plasma (PRP) injection on temporomandibular joint (TMJ) cartilage and subchondral bone healing.

Role of subchondral bone during early-stage experimental TMJ osteoarthritis

Temporomandibular joint osteoarthritis (TMJ OA) is a degenerative disease that affects both cartilage and subchondral bone. We used microarray to identify changes in gene expression levels in the TMJ during early stages of the disease, using an established TMJ OA genetic mouse model deficient in 2 extracellular matrix proteins, biglycan and fibromodulin (bgn(-/0)fmod(-/-)). Differential gene expression analysis was performed with RNA extracted from 3-week-old WT and bgn(-/0)fmod(-/-) TMJs with an intact cartilage/subchondral bone interface. In total, 22 genes were differentially expressed in bgn(-/0)fmod(-/-) TMJs, including 5 genes involved in osteoclast activity/differentiation. The number of TRAP-positive cells were three-fold higher in bgn(-/0)fmod(-/-) TMJs than in WT. Quantitative RT-PCR showed up-regulation of RANKL and OPG, with a 128% increase in RANKL/OPG ratio in bgn(-/0)fmod(-/-) TMJs. Histology and immunohistochemistry revealed tissue disorganization and reduced type I collagen in bgn(-/0)fmod(-/-) TMJ subchondral bone. Early changes in gene expression and tissue defects in young bgn(-/0)fmod(-/-) TMJ subchondral bone are likely attributed to increased osteoclast activity. Analysis of these data shows that biglycan and fibromodulin are critical for TMJ subchondral bone integrity and reveal a potential role for TMJ subchondral bone turnover during the initial early stages of TMJ OA disease in this model.     

Synovial fluid levels of VEGF and FGF-2 before and after intra-articular injection of hyaluronic acid in patients with temporomandibular disorders: a short-term study

Our purpose was to measure the temporomandibular joint (TMJ) synovial fluid (SF) levels of vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) before and after intra-articular injection of hyaluronic acid (HA) and to investigate the possible mechanism involved in the therapeutic value of HA. We analysed the synovial fluid of 30 patients with unilateral internal derangement (ID) or osteoarthritis (OA) of the TMJ (confirmed by magnetic resonance imaging and cone-beam computed tomography) and recorded clinical signs and symptoms including maximal mouth opening, subjective joint pain, and joint noise at the patient’s each visit. All clinical signs significantly improved after injection of HA, and there was no significant difference between ID and OA groups. In synovial fluid parameters, the concentration of VEGF was significantly higher before treatment with HA than after treatment, but there was no significant difference in the concentration of FGF-2 between before and after treatment. The study findings suggest intra-articular injection of HA may reduce the synovitis and improve the internal state of the TMJ in a short period.     

Quantitative bone imaging biomarkers to diagnose temporomandibular joint osteoarthritis

Bone degradation of the condylar surface is seen in temporomandibular joint osteoarthritis (TMJ OA); however, the initial changes occur in the subchondral bone. This cross-sectional study was performed to evaluate 23 subchondral bone imaging biomarkers for TMJ OA. The sample consisted of high-resolution cone beam computed tomography scans of 84 subjects, divided into two groups: TMJ OA (45 patients with TMJ OA) and control (39 asymptomatic subjects). Six regions of each mandibular condyle scan were extracted for computation of five bone morphometric and 18 grey-level texture-based variables. The groups were compared using the Mann–Whitney U-test, and the receiver operating characteristics (ROC) curve was determined for each variable that showed a statically significance difference. The results showed statistically significant differences in the subchondral bone microstructure in the lateral and central condylar regions between the control and TMJ OA groups (P <  0.05). The area under the ROC curve (AUC) for these variables was between 0.620 and 0.710. In conclusion, 13 imaging bone biomarkers presented an acceptable diagnostic performance for the diagnosis of TMJ OA, indicating that the texture and geometry of the subchondral bone microarchitecture may be useful for quantitative grading of the disease.     

A repetitive,steady mouth opening induced an osteoarthritis-like lesion in the rabbit temporomandibular joint

Although excessive mechanical stress is assumed to be one of the factors contributing to pathogenesis of temporomandibular joint (TMJ) osteoarthritis (OA), no pure mechanical-stress-induced OA model has been developed without surgical manipulation or puncture of the joint cavity. The purpose of this study was to establish a genuine mechanical-stress-induced OA model of the rabbit TMJ. In the experimental rabbits, repetitive, forced jaw-opening, 3 hrs/day for 5 days, was applied with the use of a general anesthesia protocol. By histological assessment of the TMJ articular tissues, partial eburnation of the articular cartilage, reactive marginal proliferation of the articular cartilage chondrocytes, and nested proliferation of chondrocytes in the subchondral bone area were observed at 7 days after the repetitive, forced-jaw-opening period. These results suggest that the repetitive, forced-jaw-opening protocol without surgical intervention can induce evident OA-like lesions in the rabbit TMJ, and this OA model may greatly contribute to the elucidation of the cartilage degradation mechanism in TMJ OA.     

Decreased bone marrow stromal cells activity involves in unilateral anterior crossbite-induced early subchondral bone loss of temporomandibular joints

Objective

Subchondral bone loss in mandibular condyles was reported to be induced by experimentally created unilateral anterior crossbite (UAC) which altered the occlusal load distribution and hereafter the temporomandibular joint (TMJ) remodelling process. However, the initial cellular responses are poorly understood. In the present study, changes in osteoblast and osteoclast activities in TMJ subchondral bone were investigated using the rats treated with UAC.

Design

Forty rats were randomly divided into UAC and control groups, and sampled at 2 weeks after the operation. Subchondral bone loss was evaluated by micro-CT. Osteoclast and osteoblast activities were analyzed by real-time PCR. The osteoblast differentiation of the locally isolated BMSCs from TMJ subchondral bone was assessed by Alizarin red staining. The migration of BMSCs was detected by transwell assays.

Results

Compared with the age-matched controls, TMJ subchondral bone loss was observed in the UAC-treated rats (p < 0.05). The osteoblast activity evaluated by real-time PCR and osteoblast number revealed by immunohistochemical staining were reduced in the TMJ subchondral bone of UAC rats (p < 0.05), and the capability of proliferation, migration and osteoblast differentiation were all decreased in the locally isolated BMSCs from the UAC group (p < 0.05).

Conclusions

The present data demonstrated an involvement of reduced BMSCs activity in the initiation of the mandibular subchondral bone loss at the early stage of installation of the aberrant prostheses.     

开诱导大鼠颞下颌关节骨关节炎样退变的实验性研究

目的研究过度张口对大鼠颞下颌关节软骨和软骨下骨的影响,建立异常负荷导致的关节炎动物模型。方法 10只6周龄SD雌性大鼠,随机分成两组,实验组被动张口3 h/d,持续5 d,开口度达25 mm。使用Micro-CT对髁突软骨下骨骨密度进行分析,使用甲苯胺蓝染色和免疫组化的方法观察髁突软骨细胞和细胞基质变化。结果实验组软骨下骨表面界限模糊,骨密度下降,关节后区有组织缺损。实验组关节软骨基质Ⅱ型胶原和蛋白多糖表达较对照组下降,软骨层厚度变薄,尤其表现于增殖层的变薄。结论实验性开可以导致大鼠颞下颌关节出现早期的关节炎样变化,这一模型将有助于阐明异常负荷所致的颞下颌关节炎软骨破坏内在机制的研究。     

Bone marrow nucleated cell concentrate autograft in temporomandibular joint degenerative disorders: 1-year results of a randomized clinical trial

Objectiveto assess the reliability of bone marrow nucleated cell (BMNc) intra-articular injection in patients with degenerative temporomandibular joint disorders (TMDs), and to compare its efficacy with that of hyaluronic acid (HA).Materials and methodsthis study was designed as a randomized, controlled trial of parallel groups. Patients affected by degenerative joint mandibular disorders were enrolled in this prospective clinical trial and randomly divided into two groups. The HA group underwent temporomandibular joint (TMJ) arthrocentesis and HA injection, whilst patients in the BMNc group were inoculated with BMNc inside the joint after lavage. Outcome measures were: assessing pain at rest and during motion, joint noises, chewing efficiency, and maximum interincisal opening. A postoperative MRI scan was performed and compared with the preoperative one, while examining for cartilage regeneration. Clinical and radiological data were collected from baseline to 12 months follow-up.ResultsThirty patients, 15 for each group, complaining of different degrees of unilateral TMD with internal derangement, were enrolled and treated. In both groups, significant clinical improvements were detected after the procedure up to 1 year postoperatively. The BMNc group presented significantly better pain relief than the HA group after 6 months (p = 0.028) and 12 months (p = 0.000). No significant differences were observed in terms of joint noises. In terms of chewing efficiency, the BMNc group showed positive significant differences after 12 months (p = 0.000). Maximum interincisal opening presented significantly better values in the BMNc group after 6 months (p = 0.001) and 12 months (p = 0.000). No MRI evidence of cartilage regeneration was reported.Conclusionintra-articular TMJ BMNc injection improved clinical outcomes in TMD treatment. The Results of this first human-model study are promising but further studies are needed to determine whether BMNc can represent the best treatment for TMDs.     

Preliminary evaluation of histological changes found in a mechanical arthropatic temporomandibular joint (TMJ) exposed to an intra-articular Hyaluronic acid (HA) injection, in a rat model

Objective

This study investigates the histological effects of Hyaluronic acid injections in the treatment of induced temporomandibular joint (TMJ) osteoarthritis in rats.

Study design

Twenty-four male Wister rats were subjected to induced mechanical osteoarthritis by manual hypermobility for 10 successive days. Animals were then divided into two groups; group I (control) and group II (experimental). Ten days after the induction of hypermobility, the right TMJ of the experimental animals was injected with a dose of 0.12 mg HA intra-articularly and 0.12 mg saline was injected into the left joint; while animals in the control group were left without any treatment. Two rats from group I were killed at one, two and six weeks; while 6 animals from group II were killed at one, two and four weeks post injection.

Results

The disk of the right joints in the experimental animals was of normal thickness and there was an increase in the thickness of the fibrocartilagenous layer. In the left joint; ulcerative changes in the disk were evident where the fibres were not well oriented and scalloped areas in the temporal bone area were present denoting osteoclastic activity.

Conclusions

Repeated intra-articular TMJ injection of Hyaluronic acid appears to be a safe and effective way of inhibiting the progression of osteoarthritic changes in the joint through development of articular cartilage and reducing fibrous tissue proliferation.     

关节腔注射TGF-1治疗兔颞下颌关节骨关节炎的实验研究

目的：探讨关节腔注射TGF-1治疗兔颞下颌关节骨关节炎（TMJOA）的效果。方法：24只新西兰大白兔采用双侧关节盘部分切除方法建立TMJOA动物模型,于建模后4周于右侧（实验侧）TMJ关节腔一次性注射TGF-150μl,左侧（对照侧）注射等量生理盐水。关节腔注射后12周、24周分别处死12只动物,解剖颞下颌关节,进行组织学及RT-PCR检测。结果：所有关节均表现出骨关节炎病理改变,术后12周、24周实验组病损较对照组轻,RT-PCR检测结果提示术后12周,实验组Ⅱ型胶原及蛋白聚糖表达升高,且较对照组强（P〈0.05）,IL-1及蛋白聚糖酶表达与对照组无明显差异（P〉0.05）;术后24周实验组所有检测指标与对照组无明显差异（P〉0.05）。结论：重组TGF-1因子关节腔注射能阻止TMJOA关节软骨的破坏,对TMJOA产生治疗作用。     

Changes in urinary bone resorption markers (pyridinoline,deoxypyridinoline) resulting from experimentally-induced osteoarthritis in the temporomandibular joint of rats

The purpose of this study was to quantify the urinary bone resorption markers, pyridinoline (Pyr) and deoxypyridinoline (Dpyr), excreted from experimentally-induced osteoarthritis (OA) in the temporomandibular joint (TMJ) of rats. Osteoarthritic lesions were induced by intra-articular injection of collagenase into the right TMJs of 16-week-old male rats. The whole day's urine was collected from each animal one day before the injection and 5, 7, 11 and 14 days after the injection. Urine samples were analyzed by high-perfomance liquid chromatography and fluorescence spectroscopy. Histological changes in condyle were examined by using paraffin sections with toluidine blue staining. Degenerative changes were observed in the articular cartilage of the experimental group on day 7 and day 14 after the injection of collagenase. The concentration of Pyr was remarkably high in the experimental group, and consequently the Pyr to Dpyr ratio was significantly higher (p<0.05) in the experimental group than in the control group from 7-14 days after the injection. These findings suggest that a urinary Pyr/Dpyr ratio would be available for the detection of degenerative changes in condyle relevant to temporomandibular joint osteoarthritis (TMJ OA).     

Effect of diazepam on temporomandibular joints in rats with increased occlusal vertical dimension

Anxiolytic agents, mainly benzodiazepines, have been used to treat symptomatic disorders of the temporomandibular joint (TMJ). Our aim was to evaluate the effect of diazepam on the TMJ of rats with increased occlusal vertical dimension (iOVD). Forty male rats were randomly assigned to 4 groups: control rats were given sham iOVD plus saline solution daily for 7 days. The first experimental group was given sham iOVD plus diazepam 2.5 mg/kg/intramuscularly daily for 7 days (diazepam alone group); the second had iOVD induced in molars for 7 days plus saline daily for 7 days (iOVD alone group); and the third had iOVD induced in molars for 7 days plus diazepam 2.5 mg/kg/intramuscularly daily for 7 days (iOVD plus diazepam group). At the end of each experiment the animals were killed and their bilateral TMJs were removed, randomly stained with haematoxylin and eosin and sirius-red, and immunoassayed. The thickness of condylar cartilage and of fibrous, proliferating, mature, and hypertrophic layers, number of collagen fibres, and the articular area were measured. Proinflammatory cytokines (interleukin (IL)-1α, IL-1β, IL-6, and tumour necrosis factor (TNF)-α) were also measured. ANOVA and Tukey's tests or the Kruskal–Wallis test were used to compare data among groups (α = 5%). Condylar cartilage was thicker in the control group than in the other groups, the diazepam alone group being thicker than the other 2 experimental groups. There were fewer collagen fibres in the 2 groups given diazepam than in the other 2 groups, and there were no significant differences in the area of cartilage among groups. The controls had lower concentrations of all cytokines (p < 0.05) than the 3 experimental groups, except for IL-6. Both iOVD groups had higher concentrations of IL-1α, IL-1β, and IL-6 than the diazepam alone group. Diazepam alone was associated with increased concentrations of all cytokines except IL-6. We conclude that both iOVD and diazepam induced significant changes in rats’ articular cartilage.     

rhIL-1Ra抑制大鼠颞下颌关节骨关节炎软骨破坏的研究

目的:探讨关节腔内注射重组人IL-1Ra对实验性大鼠颞下颌关节炎软骨关节修复的影响.方法:取SD大鼠24只,用关节腔内注射Ⅱ型胶原酶法建立双侧颞下颌关节骨关节炎模型,1周后,右侧(实验侧)关节腔内一次性注射重组人IL-1Ra5 μg(稀释于0.05 ml生理盐水),左侧(对照侧)注射等量生理盐水.建模后2周、4周各处死12只动物,取颞下颌关节标本进行HE染色、免疫组化染色及RT-PCR检测,用Mankin评分方法评估TMJ组织病理变化程度.另取1只SD大鼠用作空白对照,2周后处死.结果:2周时双侧颞下颌关节软骨均呈现不同程度的关节病损,实验侧和对照侧Mankin计分分别为1.33±0.52和2.00±6.63(P ＞0.05).4周时,实验侧改良和对照侧Mankin评分分别为3.00±0.63和6.50 ±0.84(P＜0.05).AD-AMTS-4、5的蛋白及mRNA表达也低于对照侧(P＜0.05).结论:颞下颌关节腔内注射重组人IL-1Ra能缓解骨关节炎导致的软骨病损,其治疗机制可能是通过抑制ADAMTS-4、5的表达来实现的.     

Age- and sex-related changes of mandibular condylar cartilage and subchondral bone: A histomorphometric and micro-CT study in rats

Objective

To quantify the age- and sex-related changes in the rat condylar cartilage and subchondral bone.

Methods

SD rats were obtained at the ages of 2, 3, 4, 5, 6 and 7 months. For each sex, the temporomandibular joints tissue blocks from four rats were subjected to histological assessment of cartilage thickness and subchondral bone architecture; for the remaining three rats, the mandibular condyles were delivered for gross measurement and evaluation of the mineralization and architecture properties of the subchondral bone by means of micro-CT.

Results

Rapid decrease of cartilage thickness but increase of subchondral bone density occurred respectively from 2 to 3 and 3 to 4 months old in female and 2 to 4 and 3 to 5 months old in male (P < 0.05), whereas rapid changes of subchondral bone architecture occurred from 3 to 4 months old in both sexes (P < 0.05). The significant enlargement of condyle size occurred at 4 or 5 months old in female but at 5 or 6 months in male (P < 0.05).

Conclusion

This study demonstrated that the rapid developmental changes of rat condylar cartilage and subchondral bone primarily occurred before 4 months of age, resulting in thinner cartilage but larger and thicker subchondral bone, and they were followed by rapid growth in condylar size. Sex differences were identified that the endochondral ossification of fibrocartilage and formation of subchondral bone were faster in female than in male rats, leading to the earlier enlargement of condyle in female than in male.     

不同剂量转化生长因子-β1对兔颞下颌关节骨关节炎的影响

探讨关节腔内注射不同剂量转化生长因子-β1（TGF-β1）对兔颞下颌关节骨关节炎（TMJOA）的影响。方法40只新西兰白兔,随机分为实验组（36只）和对照组（4只）。实验组通过双侧颞下颌关节盘部分切除建立骨关节炎模型,术后4周分别注射20、40和80 ng TGF-β1于右侧颞下颌关节内,左侧关节注射等量生理盐水。注射后6周及12周时,分批处死实验组与对照组动物。获取髁突标本后对软骨与软骨下骨分别行Micro CT检查与糖蛋白含量检测（番红-O染色）。结果 术后生理盐水组的关节呈明显的骨关节炎表现,其软骨糖蛋白含量较正常组明显降低,软骨下骨逐渐硬化。注射后6周,所有TGF-β1组糖蛋白含量均高于正常组与盐水组。其中,40 ng与80 ng组糖蛋白含量更高于20 ng组。注射后12周时,所有TGF-β1组关节软骨组织结构有序,其糖蛋白含量无组间差异,虽较6周时有所降低,但仍高于正常组。所有TGF-β1组的软骨下骨都得到显著改善,且具有与正常组类似的软骨下骨细微结构。结论 关节腔内注射TGF-β1能够有效地促进TMJOA中病变软骨的修复并阻止软骨下骨异常骨改建。     

Installing and thereafter removing an aberrant prosthesis elicited opposite remodelling responses in growing mouse temporomandibular joints

Temporomandibular joint (TMJ) displays a high remodelling capability. The current purpose was to investigate the differences between mandibular condylar remodelling responses of growing mice to installation and removal of unilateral anterior crossbite (UAC) prosthesis. Twenty‐four mice were divided into one mock control group and two UAC groups. Unilateral anterior crossbite was created by installing a pair of prosthesis to left‐side maxillary and mandibular incisors. Unilateral anterior crossbite was removed in removal group at 3 weeks but remained in UAC group. Temporomandibular joints were sampled at 7 weeks. Changes in condylar cartilage and subchondral bone were assessed by histology and in vivo micro‐CT. Real‐time PCR and immunohistochemistry were performed to evaluate expression changes in ADAMTS‐5, MMP‐3, MMP‐9, MMP‐13, IL‐1, TNF‐α, OPG and RANKL. Statistical analysis was performed at α = 0·05. Temporomandibular joint cartilage degradation was induced by UAC as previously reported but was reversed by removal of UAC. The dropped cartilage thickness, chondrocyte number and collagen II‐positive area, the increased expression levels of Adamts‐5, Mmp3, 9, 13, Tnf‐α and Il‐1β in cartilage, the decreased ratio of OPG/RANKL in both condylar cartilage and subchondral bone, the loss of TMJ subchondral bone and the increase in the TRAP‐positive cells in subchondral bone were all reversed in the removal group (P < 0·05). The growing mouse TMJ condyle displays a high remodelling capability which can be degenerative and rehabilitative, respectively, in response to placement and thereafter removal of the aberrant prosthesis. Eliminating aberrant prosthesis is helpful to promote the degraded condyle to recover.     

The effects of high molecular weight hyaluronic acid (Hylan G-F 20) on experimentally induced temporomandibular joint osteoartrosis: part II

The aim of this study was to determine the efficacy of Hylan G-F 20 on experimentally induced osteoarthritic changes in rabbit temporomandibular joint (TMJ). A 3 mg/ml concentration of sodium mono iodoacetate (MIA) had been injected into both joints of 24 rabbits to create osteoartrosis. The study group was injected with Hylan G-F 20 in one joint and saline in the contralateral joint as a control (once a week for 3 weeks). Histological changes in articular cartilage, osteochondral junction, chondrocyte appearance and subchondral bone were determined at 4, 6, and 8 weeks. Regarding cartilage, there was a statistically significant difference between the two groups at 4 weeks. Degenerative bony changes to subchondral bone were significantly higher in the controls. No statistical difference was found in the study group at 6 weeks. A positive correlation was found between osteochondral junction and subchondral bone in the study group at 8 weeks. The changes in chondrocyte appearance were significantly decreased in the study group at all follow-up times. Intra-articular injection of Hylan G-F 20 decreased cartilage changes in early stage TMJ osteoartrosis and clustering of chondrocytes showed the chondroprotective effects of Hylan G-F 20 caused by hypertrophic responses.