SOX Trio Decrease in the Articular Cartilage with the Advancement of Osteoarthritis

SOX trio (SOX-5, SOX-6, and SOX-9) maintain the chondrocytic phenotypes and are vital for chondrogenesis in embryonic development. The purpose of this study is to investigate the change in the expression of SOX trio with the advancement of osteoarthritis (OA) in human articular cartilage (AC). Human OA samples from eight patients were obtained from the distal femoral condyles during total knee arthroplasty. Minimally OA cartilage taken from areas with no obvious surface defects on lateral condyles was compared with advanced OA cartilage obtained from areas within 1 cm of overt lesion located on medial condyle surface. SOX-5, SOX-6, and SOX-9 gene expressions significantly decreased by 41% (p = 0.047), 46% (p = 0.047), and 56% (p = 0.029) in advanced OA area compared with the minimally OA area. There was a significant decrease in aggrecan and type II collagen (COL2A1) gene expressions by 73% (p = 0.029) and 65% (p = 0.029), respectively, in advanced OA area compared with the minimally OA area. From Western blotting and immunohistochemistry, SOX-5, SOX-6, SOX-9, type II collagen, and aggrecan protein expressions also significantly decreased in advanced OA cartilage compared with minimally OA cartilage. DNA methylation study of SOX-9 promoter regions revealed no difference in the epigenetic status between the two areas. It is concluded that SOX trio gene and protein decreased with advancement of OA in human articular cartilage.     

Some Biochemical and Biophysical Parameters for the Study of the Pathogenesis of Osteoarthritis: a Comparison Between the Processes of Ageing and Degeneration in Human Hip Cartilage

We have investigated the changes in some of the biochemical and biophysical properties of human femoral head cartilage on the one hand during ageing and on the other hand in osteoarthritis. Topographical variations were also investigated.

The parameters studied were those relevant to cartilage function, viz., proteoglycan concentration (as expressed by the concentration of negatively charged groups), the rate of glycosaminoglycan synthesis, water content, osmotic pressure and fluid loss during compression.

During ageing the tixed charge density was found to increase at all sites of the femoral head provided fibrillation was absent: osmotic pressure increased accordingly whilst loss of fluid under the effect of externally applied compression diminished. In cartilage from osteoarthritic joints the opposite changes were found.

The rate of GAG synthesis varied considerably with site on the femoral head. It decreased somewhat with age on the superior surface, but increased on the inferior surface. When the same sites were compared, the rate of GAG synthesis in cartilage from osteoarthritic heads was either the same as or lower than in cartilage form normal heads in the same group.     

Quantification of Stiffness Change in Degenerated Articular Cartilage Using Optical Coherence Tomography-Based Air-Jet Indentation

Articular cartilage is a thin complex tissue that covers the bony ends of joints. Changes in the composition and structure of articular cartilage will cause degeneration, which may further lead to osteoarthritis. Decreased stiffness is one of the earliest symptoms of cartilage degeneration and also represents the imperfect quality of repaired cartilage. An optical coherence tomography (OCT)-based air-jet indentation system was recently developed in our group to measure the mechanical properties of soft tissues. In this study, this system was applied to quantify the change of mechanical properties of articular cartilage after degeneration induced by enzymatic digestions. Forty osteochondral disks (n = 20 × 2) were prepared from bovine patellae and treated with collagenase and trypsin digestions, respectively. The apparent stiffness of the cartilage was measured by the OCT-based air-jet indentation system before and after the degeneration. The results were also compared with those from a rigid contact mechanical indentation and an ultrasound water-jet indentation. Through the air-jet indentation, it was found that the articular cartilage stiffness dropped significantly by 84% (p < 0.001) and 63% (p < 0.001) on average after collagenase and trypsin digestions, respectively. The stiffness measured by the air-jet indentation system was highly correlated (R > 0.8, p < 0.001) with that from the other two indentation methods. This study demonstrated that the OCT-based air-jet indentation can be a useful tool to quantitatively assess the mechanical properties of articular cartilage, and this encourages us to further develop a miniaturized probe suitable for arthroscopic applications.     

木瓜蛋白酶诱导大鼠膝早期骨关节炎软骨表面的电镜扫描

背景：木瓜蛋白酶注射建立骨性关节炎动物模型是用于骨关节炎防治研究的常用方法之一。 目的：观察木瓜蛋白酶和L-半胱氨酸混合注射诱导大鼠膝早期骨关节炎进程中扫描电镜下软骨表面形态学变化。 方法：2%木瓜蛋白酶和0.03 mol/L左旋半胱氨酸按2∶1比例混匀,取0.15 mL注射至SD大鼠右膝关节腔诱导骨关节炎模型,左膝注射等量生理盐水为对照组,另取2只4膝不做处理为正常对照组,于注射后第2,4,6周后分别使用扫描电镜观察股骨内侧髁关节软骨表面形态学变化。 结果与结论：正常和对照组可见表面分布较均匀的浅坑。木瓜蛋白酶和L-半胱氨酸混合注射2周后大鼠软骨表面出现凹凸不平,皱缩扭曲变形;4周表面变薄,局部出现小裂纹;6周出现深大裂纹,软骨缺损。提示2%木瓜蛋白酶和0.03 mol/L左旋半胱氨酸混合注射诱导的早期骨关节炎模型的时间节点可以定在4-6周。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

关节软骨力学特征研究进展

骨关节炎(osteoarthritis OA)是一种以关节疼痛和僵硬为特征的慢性退行性关节疾患,好发于老年人群。OA发病缓慢,病程较长,早期临床表现和组织学改变均不明显,限制了疾病的早期诊断与治疗。关节软骨微观结构决定了软骨宏观力学特性。软骨微观结构具有区域差异性,导致软骨的力学性能也具有区域依赖性,从软骨浅表区到深区软骨抗负荷、抗形变能力逐渐增加。然而,在OA病程发展过程中,软骨微观构成改变导致OA软骨抗负荷、抗形变能力降低。通过检测关节软骨的微观构成可以推测软骨的力学特性,反之检测软骨的力学指标可以了解软骨早期的微观改变,从而有助于了解OA的病程发展,便于疾病的早期诊断。综述近年来关节软骨在正常和急慢性损伤状态下力学性能的相关研究文献,阐述软骨结构与力学性能之间的关系,为OA的病程发展、早期诊断与治疗提供进一步理论依据。     

关节软骨力学特性间接预测方法的研究进展

关节软骨具有非常优异的力学特性,是影响人体运动、载荷传递的关键因素之一.随着人们参与体育运动的增多以及老龄化程度的加剧,出现关节软骨损伤及其相关病症的人数显著增多.实现关节软骨力学特性的有效表征,是对关节软骨进行损伤评估和功能评价的核心环节.总结当前国内外关于关节软骨力学特性间接测量方法的研究进展,并对关节软骨力学特性...     

高频超声对关节软骨消肿与肿胀行为的定量分析

关节软骨可减轻关节滑动中所产生的关节面间的摩擦,具有负重传导、润滑及耐磨损的特性。关节软骨肿胀属性的改变可作为检测早期关节炎的指标之一。本研究的目的在于利用高频超声技术和信号处理技术建立一个实时超声监测系统,以一种非接触、无损的方法研究软骨的瞬时渗透性消肿(收缩)及肿胀(膨胀)行为。样本取自新鲜成年牛膝盖骨,通过改变外溶液的浓度引入渗透压,促使软骨发生收缩膨胀反应,利用实时超声监测系统进行无损测量。实验表明关节软骨的肿胀消肿过程出现“过激松弛”现象,最大收缩膨胀应变的绝对值分别为0.75%±0.57%和0.28%±0.28%,膨胀应变与收缩应变具有显著性差异(p<0.05)。同时发现软骨内超声速度随时间的指数性变化可以表征离子的渗透过程。实验证明该超声系统具有良好的可重复性(组内相关系数ICC>0.98)和可靠性(相对误差<5%)。应用高频超声技术不仅可无损量化地研究软骨的渗透性消肿膨胀行为,而且为今后研究软骨病变及早期发现关节炎提供一个有效可行的方法。     

股骨颈骨折后髋关节软骨退变的生物力学研究

在动物模型上研究股骨颈骨折后髋关节软骨退变在发生、发展、转归过程中软骨厚度和生物力学特性改变及其与伤后时间的关系。用新西兰白兔60只作股骨颈基底截骨制作骨折动物模型，于术后2、4、6、8、12、16周采用压凹法测定关节软骨厚度和生物力学特性。免股骨颈骨折后关节软骨持续增厚，6周达高峰，随后软骨迅速磨损、变薄；骨折后4周起软骨退变失代偿，弹性和机械强度进行性大幅度下降，退变至骨关节炎。股骨颈骨折后保守治疗形成局部低应力环境，关节软骨缺乏动态载荷，基质胶原网络迅速降解所引起的生物力学特性降低是导致并维持软骨退变不断前进的动力。     

骨性关节炎对膝关节软骨粘弹性影响实验研究

研究了正常国人新鲜尸体膝关节软骨和骨性关节炎膝关节软骨的粘弹性力学性质.对正常和病态膝关节软骨进行一维拉伸应力松弛、蠕变实验,得出了应力松弛、蠕变实验数据和曲线,以回归分析的方法处理应力松弛、蠕变实验数据,得出了归一化应力松弛函数、归一化蠕变函数表达式.以冯元桢教授的准线性理论得出了正常组和病态组膝关节软骨松弛函数表达式,并对实验结果进行了分析讨论.     

冷冻保存异体骨膜移植治疗髋关节骨性关节炎

目的：报道采用冷冻保存胚胎颅骨骨膜移植修复髋关节软骨大面积缺损的治疗结果。方法：自1990年5月—1994年4月，对42例(47侧)髋关节软骨全厚缺损采用冷冻保存胚胎颅骨骨膜移植进行修复，其中14例股骨头骨质重度坏死者，同时施行带旋髂深血管髂骨植骨。对34例(38侧)髋关节进行了2～6年(平均40个月)随访。结果：按照吴之康髋关节人工置换术后疗效评定标准．术前平均得分6．4分，术后平均得分15.8分，优良25例，很好5例，好3例，尚可1例。结论：与自体移植物修复关节软骨大面积缺损相比，本方法无附加损伤，具有移植材料来源充分，取材量大．形态与股骨头相似等特点，是治疗髋关节软骨大面积缺损的一种有效方法。     

先天性髋关节发育不良股骨近端髓腔内径曲线形态

目的测量并分析国内先天性髋关节发育不良(developmental dysplasia of the hip,DDH)患者股骨近端形态参数与髓腔内径曲线,为DDH股骨柄设计提供参考依据。方法进行股骨三维重建后,测量并比较分析30名正常人(30髋,男21名,女9名,平均年龄29.4岁)和64名DDH患者(74髋,男12名,女52名,平均年龄45.3岁)股骨近端形态参数和多个高度上髓腔内外径、前后径,建立不同人群的髓腔内径曲线并进行比较分析。结果 DDH患者与正常人群相比,前倾角(26.39°±14.74°vs 15.68°±7.95°)显著较大(P=0.001),颈干角(125.65°±5.73°vs 129.19°±5.80°)、峡部高度[(99.14±14.62) mm vs (110.13±11.73) mm]、髓腔开大指数[(3.63±0.77) vs (4.45±0.79)]、股骨头直径[(44.01±5.75)mm vs (47.26±3.94)mm]和偏心距[(31.80±3.82)mm vs (36.42±4.84)mm]则显著较小(P0.05)。结合测量所得的髓腔前后径、内外径与所拟合的内径曲线,DDH近端髓腔呈现的特点为内外径变狭窄、前后径向前偏移。在不同分型DDH中,股骨的变形程度随着分型增大愈发严重,CroweⅣ型DDH患者与其他分型间的股骨髓腔形态存在较大差异。结论 DDH患者的平均股骨近端曲线与正常人群存在较大差异,且DDH的不同分型间也存在形态差异。研究结果有助于定量了解DDH患者的股骨近端形态特征,为设计适用于DDH患者的新型股骨柄提供参考依据。     

Wnt signalling in the articular cartilage: A matter of balance

Degradation of the articular cartilage is a hallmark of osteoarthritis, a progressive and chronic musculoskeletal condition, affecting millions of people worldwide. The activation of several signalling cascades is altered during disease development: among them, the Wnt signalling plays a pivotal role in the maintenance of tissue homeostasis. Increasing evidence is showing that its activation needs to be maintained within a certain range to avoid the triggering of degenerative mechanisms. In this review, we summarise our current knowledge about how a balanced activation of the Wnt signalling is maintained in the articular cartilage, with a particular focus on receptor-mediated mechanisms.     

缺损关节软骨在循环压缩载荷下棘轮行为的实验研究

目的研究缺损软骨在循环压缩载荷下的棘轮应变行为,探索缺损关节软骨的损伤演化规律。方法取新鲜的成年猪股骨远端关节软骨,对不同缺损深度软骨试样进行不同参数的三角波循环加载。结合非接触式数字图像技术,获得软骨不同层区的棘轮应变。结果随循环加载圈数的增加,软骨各层棘轮应变均表现为先急剧增大,然后缓慢增加并趋于平稳,由浅层到深层棘轮应变逐渐减小。各层区对循环圈数响应不同,浅层在50圈内应变增加较快,中层在100圈内应变增加较快,深层在75圈内应变增加较快。除了中层区域响应有滞后性,浅层、深层的棘轮应变与应力幅值、缺损深度呈正相关,与加载速率呈负相关。结论软骨的棘轮行为受软骨的特殊结构的影响,缺损使软骨各层区的应变增大,易造成损伤加剧。实验结果为组织工程软骨的构建提供参考依据。     

Assessing macroscopic and microscopic indicators of osteoarthritis in the distal interphalangeal joints: a cadaveric study

Osteoarthritis is manifested both by macroscopically visible lesions and by specific histological indicators. Although traditional views of the disease process invoke physical abrasion of joint surfaces, recent studies indicate that tissue-level changes may precede grossly visible lesions of articular cartilage. This study investigates the association between gross and histological indicators of osteoarthritis at the manual interphalangeal joints, and examines a sequence of events that may lead to the onset of cartilage degeneration. Interphalangeal joints from the hands of nine cadavers were dissected, of which 52 joints were collected and further evaluated. Gross degradation of the proximal articular surface was graded on a scale of 0-3 (with 0 representing normal cartilage with no visible lesions). Osteoarthritic lesions were found in 86% of specimens and showed no preferential occurrence between males and females or right and left hands. Histological analysis indicated that known microscopic indicators of osteoarthritis always occur in Grade 1-3 specimens, but can also be recognized in some macroscopically normal specimens. Many macroscopically normal specimens exhibited chondrocyte clustering (28.6%) and/or tide mark irregularities (57%), indicating that these features are most likely the earliest to develop in the progression of osteoarthritis. It is possible that the initiating etiology is thickening of the subchondral bone, but this was not directly observed. Results indicate significant thinning of the cartilage as macroscopic degradation progresses. Our study supports, with slight modification, a previously proposed cascade of histological changes that may ultimately lead to the physical destruction of articular cartilage.     

髋臼内陷技术对成人DDH全髋关节置换术髋臼杯生物力学影响的有限元分析

目的 探讨髋臼内陷技术对成人发育性髋关节发育不良（developmental dysplasia of the hip,DDH）髋关节置换术后髋臼假体的生物力学效应。方法 获取1名成人单侧DDH患者双侧髋关节CT图像数据,进一步构建患侧半骨盆有限元模型,在此基础上,建立臼杯不同内陷水平的有限元模型,对比分析原位组和不同水平内移组之间的生物力学差异。结果 在模拟拔出试验中,原位组最大抗拔出载荷强度为1 166 N;相比原位组,4 mm和8 mm内移组抗拔出载荷强度分别增加了45.8%和57.1%;原位组髋臼假体在步态周期站立位相载荷工况下的臼杯-骨界面最大微动为166.4 μm,内移4 mm及8 mm组相对原位组分别减少了46.2%和62.1%。对于臼杯植入后髋臼周围即刻应力分布,不同组别之间的差异并不显著;而在步态周期站立位相载荷工况下,原位组髋臼周围平均应力及峰值应力均最小,平均应力随内移程度的增加而增大,内移4 mm组峰值应力最高。结论 相较原位植入假体,髋臼内陷技术可以提高假体初始稳定性,稳定性和内移程度成正比。但内移程度不足导致骨覆盖面积不足时,臼杯-骨界面边缘应力显著增加,可能会导致假体相关并发症风险的升高。     

Mild degenerative changes of hip cartilage in elderly patients: an available sample representative of early osteoarthritis

This study investigated the cellular and molecular changes which occur in cartilage from adults with femoral neck fracture (FNF) and osteoarthritis (OA), and explored the similarities in hip cartilage obtained from elderly patients and patients with early OA. Femoral heads were retrieved from 23 female patients undergoing total hip arthroplasty (THA). This group included 7 healthy patients with FNF (hFNF), 8 elderly adults with FNF (eFNF), and 8 elderly patients with hip OA (OA). After high-field MRI T2 mapping, osteochondral plugs were harvested from the weight-bearing area of femoral heads for subsequent macroscopic, histologic, and immunochemical evaluation. Additionally, the contents of cartilage matrix were analyzed, and gene expression was detected. The surface of cartilage from hFNF and eFNF patients appeared smooth, regular, and elastic, whereas it showed irregularities, thinning, and defects in OA patients. Elevated T2 values and decreased accumulation of glycosaminoglycans (GAGs) were detected in cartilage from eFNF patients. Furthermore, type I collagen accumulation was slightly increased and type X collagen concentration was obviously elevated in eFNF patients; however, type II collagen distribution and the contents and anisotropy of collagen fibrils in eFNF patients showed no significant changes. Consistent with histology and immunohistochemical results, aggrecan was downregulated and type X collagen was upregulated, while collagens types I and II showed no significant changes in eFNF patients. The cellular and molecular characteristics of hip cartilage in eFNF patients who showed no symptoms of OA were similar to those in patients with mild OA. Thus, eFNF cartilage can serve as a comparative specimen for use in studies investigating early OA.     

Nitroxide Synthase Activity as a Marker of Early Stages of Experimental Cartilage Dysmetabolism

Time course of nitroxide synthase activity in the knee joint cartilage was studied in animals with experimental anterior instability of the knee joint. A significant increase in nitroxide synthase activity in chondrocytes was paralleled by a progressive decrease in glycosaminoglycan content in the cartilaginous matrix and subsequent destruction of the cartilage cytoarchitectonics.     

Age-Related Changes in the Synthesis of Matrix Macromolecules by Bovine Articular Cartilage

Calf and mature cow articular cartilage was labeled in vitro with [³⁵S]SO₄ and [³H]glycine and kinetics of incorporation of both isotopes by cartilage fragments was determined by scintillation spectroscopy. The cartilage fragments were then extracted in sequence with 4M GuHCl (Guanidium chloride) and pepsin. The pepsin digest was adjusted to 1.3 M NaCl and pepsin-solubilized collagen salted out. The 4M GuHCl extract, collagen and pepsin-resistent residue were then freeze-dried. The 4M GuHCl extract was further fractionated by DEAE (Diethylaminoethyl) 52 ion exchange chromatography to obtain protein and PG (Proteoglycan) fractions. The protein fraction was also characterised by SDS-PAGE and PG fraction by Sepharose C1–2B chromatography under associative conditions in the presence and absence of an exogenous HA (Hyaluronic acid). The GAG (Glycosaminoglycan) side chains of the PG samples were analysed by Sephadex G-200 column chromatography and their composition determined by paper chromatography after chondroitinase ABC digestion.

Linear incorporation of both isotopes was observed from 1 to 18 hours of incubation and roughly equal amounts of f³⁵S]SO₄ counts were found on per cell bases in both cartilages although less [³H]glycine was incorporated by cow chondrocytes. It was also found that calf chondrocytes synthesize much greater proportion of the collagen whereas the cow cells synthesize PGs of smaller hydrodynamic sizes, bearing shorter GAG side chains that are enriched in KS (Keratan sulfate) and Ch-6S (Chondroitin-6 sulfate isomer). A failure of cow ³⁵S-PGs monomers to interact with an exogenous HA in the presence of other extracted components was also demonstrated.

The relevance of these findings for the mechanism of cartilage damage in aging and osteoarthritis is discussed.     

Minor Influence of Lifelong Voluntary Exercise on Composition,Structure, and Incidence of Osteoarthritis in Tibial Articular Cartilage of Mice Compared with Major Effects Caused by Growth,Maturation, and Aging

We investigated the effects of lifelong voluntary exercise on articular cartilage of mice. At the age of 4 weeks C57BL mice (n = 152) were divided into two groups, with one group serving as a sedentary control whereas the other was allowed free access to a running wheel from the age of 1 month onward. Mice were euthanized at four different time points (1, 2, 6, and 18 months of age). Articular cartilage samples were gathered from the load-bearing area of the tibial medial plateaus, and osteoarthritis was graded. Additionally, the proteoglycan content distribution was assessed using digital densitometry, collagen fibril orientation, and parallelism with polarized light microscopy, and collagen content using Fourier transform infrared imaging spectroscopy. The incidence of osteoarthritis increased with aging, but exercise had no effect on this trend. Furthermore, the structure and composition revealed significant growth, maturation, and age-dependent properties. Exercise exerted a minor effect on collagen fibril orientation in the superficial zone. Fibril orientation at 2 months of age was more perpendicular to surface (p < 0.05) in controls compared with runners, whereas the situation was reversed at the age of 18 months (p < 0.05). The collagen content of the superficial zone was higher (p < 0.01) at the age of 18 months in controls compared with runners but the proteoglycan content did not display any exercise-dependent changes. In conclusion, growth, maturation, and aging exerted a clear effect on integrity, structure, and composition of medial tibial plateau articular cartilage in mice, whereas lifelong voluntary exercise had only a minor effect on collagen architecture and content.     

Sodium relaxation times in the knee joint in vivo at 7T

The sodium concentration correlates directly with the concentration of proteoglycans (PG) in cartilage, the loss of which is an early signature of osteoarthritis (OA). As a result, quantitative sodium MRI is a promising technique for assessing the degradation of articular cartilage in patients with OA. Sodium relaxation times can also provide information on the degradation of cartilage: it has already been shown on bovine cartilage that T(1) and T2long are longer and T2short shorter when the PG concentration decreases. In this study, sodium T(1), T2*short and T2*long relaxation maps were measured in vivo at 7 T on 8 healthy volunteers and in 4 different regions of the cartilage in the knee joint. The patellar, femoro-tibial medial, lateral, and femoral condyle cartilage have an average T(1)~20 ms, but different T2*short (from 0.5 ms to 1.4 ms) and T2*long (from 11.4 ms to 14.8 ms). Statistically significant differences in T(1), T2*short and T2*long were observed between the different regions in cartilage (p < 10(- 5)). Statistical differences in T(1) were also observed between male and female data (p < 10(- 5)). These relaxation times measurements can further be applied as correction factors for sodium concentration maps in vivo and can also be useful as complementary information to quantitative sodium MRI in the quest for detecting early OA. These measurements were done on low resolution sodium images in order to acquire sufficient quality data for fitting (5 images for T(1) and 9 images for T2*) while keeping the total time of acquisition of the data reasonable for the volunteer's comfort (1 h 15 min).