Morphological,biochemical and mechanical properties of articular cartilage and subchondral bone in rat tibial plateau are age related

The purpose of this study was to investigate age‐related changes in the morphological, biochemical and mechanical properties of articular cartilage (AC) and subchondral bone in the rat tibial plateau. Female Wistar rats were grouped according to age (1, 3, 5, 7, 9, 11, 13, 15, 16 and 17 months, with 10 rats in each group). The ultrastructures, surface topographies, and biochemical and mechanical properties of the AC and subchondral bone in the knee joints of the rats were determined through X‐ray micro‐tomography, histology, immunohistochemistry, scanning electron microscopy (SEM), atomic force microscopy and nanoindentation. We found that cartilage thickness decreased with age. This decrease was accompanied by functional condensation of the underlying subchondral bone. Increased thickness and bone mineral density and decreased porosity were observed in the subchondral plate (SP). Growth decreased collagen II expression in the tibial cartilage. The arrangement of trabeculae in the subchondral trabecular bone became disordered. The thickness and strength of the fibers decreased with age, as detected by SEM. The SP and trabeculae in the tibial plateau increased in roughness in the first phase (1–9 months of age), and then were constant in the second phase (11–17 months of age). Meanwhile, the roughness of the AC changed significantly in the first phase (1–9 months of age), but the changes were independent of age thereafter. This study gives a comprehensive insight into the growth‐related structural, biochemical and mechanical changes in the AC and subchondral bone. The results presented herein may contribute to a new understanding of the pathogenesis of age‐related bone diseases.     

淫羊藿苷治疗骨性关节炎过程中对关节软骨、软骨下骨、滑膜等影响的机制

文题释义： 淫羊藿苷：为淫羊藿干燥茎叶的提取物,呈淡黄色针状结晶粉末, 相对分子质量为676.65, 属黄铜类化合物,现代药理学研究发现其具有很强的生物活性, 对骨组织、免疫系统、肿瘤组织、神经系统、生殖系统、内分泌系统和心血管系统等具有显著作用。 滑膜：是关节囊的内层。滑膜呈淡红色,平滑闪光,薄而柔润,由疏松结缔组织组成,其功能是制造和调节滑液等。滑膜直接附着于关节软骨的边缘并向内贴附在关节囊内的非关节区域,覆盖在关节囊、关节内韧带、骨与肌腱表面。滑膜分泌滑液,在关节活动中起重要作用。背景：淫羊藿苷是具有补肾强筋健骨功效的淫羊藿的主要有效成分,近年来大量的研究发现淫羊藿苷在治疗骨性关节炎方面有着显著作用。 目的：综述淫羊藿苷治疗骨性关节炎的分子机制研究进展。 方法：第一作者应用计算机以“Icariin、Osteoarthritis、Cartilage、Subchondral bone、Synovial membrane 、Synovium、Inflammation”及“淫羊藿苷、骨关节炎、骨性关节炎、软骨、软骨下骨、滑膜、炎症”作为主题词检索PubMed、中国知网、万方、维普等数据库相关文献,按入选标准及排除标准进行筛选,最终纳入42篇文献进行分析。 结果与结论：淫羊藿苷通过促进骨髓间充质干细胞的成软骨分化及增强软骨细胞和成骨细胞的增殖,抑制软骨细胞外基质的降解、降低破骨细胞的活性和减轻炎症因子所致的滑膜炎症反应来有效的治疗骨性关节炎。但其最佳有效剂量及浓度安全性仍需要大量实验研究,目前绝大部分实验仍停留在动物及组织细胞等基础实验,尚需要大量临床研究,继续完善其具体机制,以期为淫羊藿苷治疗骨关节炎提供循证医学证据。ORCID:0000-0002-2013-743X(余绍涌)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     

VEGF-A is associated with early degenerative changes in cartilage and subchondral bone

Paired cartilage and subchondral bone of subjects with no clinical history of joint disorders were analyzed to determine whether antioxidant enzymes, inflammatory cytokines and growth factors can be linked to a pre-osteoarthritis. Tissue explants were phenotyped according to Osteoarthritis Research Society International grading and micro-computed tomography, and also screened for the expression of several markers using quantitative polymerase chain reaction. The expression of these same genes was measured in SW1353 cells treated with hydrogen peroxide, to gain insight into the pathways involved with oxidative stress responses. Vascular endothelial growth factor A (VEGF-A) was up-regulated in the cartilage samples that showed early cartilage or bone degeneration. Oxidative stress in chondrocytes provoked up-regulation of interleukin-1β, interleukin-6, aggrecan, and SRY-box containing gene 9. Our results confirm the hitherto evidence of the deteriorating effects of the oxidative stress on cartilage and suggest the link between VEGF-A and pre-osteoarthritis.     

The response of bone, articular cartilage and tendon to exercise in the horse

Horses can gallop within hours of birth, and may begin training for athletic competition while still growing. This review cites studies on the effects of exercise on bone, tendon and articular cartilage, as detected by clinical and research imaging techniques, tissue biochemical analysis and microscopy of various kinds. For bone, alterations in bone mineral content, mineral density and the morphology of the mineralized tissue are the most common end-points. Apparent bone density increases slightly after athletic training in the cortex, but substantially in the major load paths of the epiphyses and cuboidal bones, despite the lower material density of the new bone, which is deposited subperiosteally and on internal surfaces without prior osteoclastic resorption. With training of greater intensity, adaptive change is supervened by patho-anatomical change in the form of microdamage and frank lesions. In tendon, collagen fibril diameter distribution changes significantly during growth, but not after early training. The exact amount and type of protracted training that does cause reduction in mass average diameter (an early sign of progressive microdamage) have not been defined. Training is associated with an increase in the cross-sectional area of some tendons, possibly owing to slightly greater water content of non-collagenous or newly synthesized matrix. Early training may be associated with greater thickness of hyaline but not calcified articular cartilage, at least in some sites. The age at which adaptation of cartilage to biomechanical influences can occur may thus extend beyond very early life. However, cartilage appears to be the most susceptible of the three tissues to pathological alteration. The effect of training exercise on the anatomical or patho-anatomical features of connective tissue structures is affected by the timing, type and amount of natural or imposed exercise during growth and development which precedes the training.     

Articular calcified cartilage canals in the third metacarpal bone of 2-year-old thoroughbred racehorses

We describe morphological aspects of the articular calcified cartilage mineralizing front 'tidemark' in the distal joint surface of the third metacarpal bone from 14 horses. Compositional backscattered electron scanning electron microscopy and confocal scanning light microscopy were conducted on polymethylmethacrylate (PMMA)-embedded medio-lateral slices. After maceration, scanning electron microscopy (SEM) was used to study the calcified cartilage surface in the 'wedges' intervening between the slices. An anatomically reproducible clustering of canals in the calcified cartilage was found at one site on the sagittal ridge in all the horses. The site is one that is relatively less loaded during joint function. These canals through calcified cartilage result from osteoclastic resorption (cutting cones) penetrating from bone through to the non-mineralized hyaline articular cartilage. Their presence may indicate a pathway for connection between bone and cartilage extracellular fluid. In one horse, repair of such canals by plugging with new calcified cartilage was demonstrated. Differences in the degree of mineralization of regions of cartilage were seen in the combined compositional-cum-topographical backscattered SEM images of the macerated 'tidemark' front. More-or-less circular patches of lower mineralization density were frequently centred on (and may possibly originate from) canals. These microanatomical features should be searched for in other joints, at other ages and in other species to discover their frequency and significance.     

组织工程软骨与柚皮苷联合修复兔膝关节软骨缺损的组织学证实

背景：目前临床上虽有多种方法用于治疗软骨缺损,但没有从根本上解决关节软骨缺损修复问题。 目的：通过组织学研究进一步评价柚皮苷结合组织工程软骨修复兔关节软骨缺损的效果。 方法：取兔骨髓间充质干细胞体外增殖后,复合于改建后的脱细胞真皮基质载体上,制成组织工程软骨,植入到兔膝关节软骨缺损,并以柚皮苷汤灌胃,于 4,8周后分别对修复组织进行苏木精-伊红、Masson三色染色、甲苯胺蓝染色、Ⅱ型胶原染色、Ⅹ型胶原染色等组织学检查。 结果与结论：术后8周, 柚皮苷结合干细胞复合体组缺损处修复组织变成乳白色,半透明光滑组织,缺损修复组织与周围正常软骨已基本难区分,表面光滑。组织学检查发现修复缺损处基本为新生软骨填充。结果证实,柚皮苷结合组织工程软骨能提高家兔膝关节软骨缺损的修复质量。 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：     

微骨折技术与骨软骨移植治疗关节软骨缺损

背景：关节镜下微骨折治疗与骨软骨移植是关节软骨缺损主要的治疗方法之一,具有广阔的应用前景。 目的：探讨关节镜下微骨折治疗与自体和同种异体骨软骨移植治疗膝骨关节炎合并关节软骨缺损的效果。 方法：应用关节镜下微骨折治疗清理术结合软骨缺损区微骨折术治疗膝骨关节炎的临床疗效、临床症状及Tegner运动评级判定疗效并随访观察3-24个月。自体骨软骨移植治疗关节软骨缺损的患者进行观察随访,通过评价移植后关节活动度、临床症状的改善、关节影像学检查等评估自体骨软骨移植治疗的效果。并对同种异体骨软骨移植治疗关节软骨缺损进行动物实验研究,通过对移植部位的大体观察、组织学观察以及免疫组织化学染色观察,评估同种异体骨软骨移植治疗的效果。 结果与结论：关节软骨缺损应用关节镜下微骨折治疗后的患者,关节清理术结合软骨缺损区微骨折术总有效率89.7%。关节软骨缺损应用自体骨软骨移植治疗后的患者,关节疼痛、肿胀的症状改善,关节活动度正常,偶有关节静息痛或活动后轻微疼痛,影像学检查见移植骨软骨位置良好,修复愈合良好。关节软骨缺损应用同种异体骨软骨移植治疗后的实验动物,关节活动度正常,移植关节面光整,关节软骨被透明软骨覆盖,细胞有序排列,软骨基质分泌,修复软骨Ⅱ型胶原免疫组织化学染色强阳性。     

温阳益髓中药干预兔膝骨关节炎软骨基质金属蛋白酶的表达

背景：目前临床上关于温阳益髓中药治疗膝骨关节炎对软骨基质金属蛋白酶表达影响的研究还较少有报道。 目的：制作兔膝骨关节炎模型观察温阳益髓中药对软骨基质金属蛋白酶表达的影响。 方法：健康成年新西兰大白兔96只,随机选取72只采用石膏外固定方法制作兔膝骨关节炎模型。确定造模成功后再随机分为3组,模型组不做处理;中药治疗组每日灌胃方药提取液24 mL/kg,药物对照组每日灌胃葡立胶囊(盐酸氨基葡萄糖)24 mg/kg,1次/d,至造模成功后8周。另外24只新西兰大白兔作为空白对照。 结果与结论：PCR方法定量分析骨关节炎模型组软骨组织中基质金属蛋白酶1、基质金属蛋白酶3、基质金属蛋白酶13表达水平均显著高于其他3组。中药治疗组及药物对照组中基质金属蛋白酶1、基质金属蛋白酶3及基质金属蛋白酶13的表达较模型组明显降低。说明温阳益髓中药治疗兔膝骨关节炎能够有效抑制兔骨关节炎软骨基质金属蛋白酶的表达。 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：     

Rapid decalcification of articular cartilage and subchondral bone using an ultrasonic cleaner with EDTA

Articular cartilage and subchondral bones were used to be the samples for studying effects of drugs in the joint degenerative diseases such as osteoarthritis. Because of the deposition of mineral salts, articular cartilage and subchondral bones require decalcification process to soften the tissues. EDTA is a chelating agent that is commonly used to remove mineral salts, but this step is time-consuming and can take as long as 45 days. Commercial ultrasonic cleaner and microwave oven were reported to reduce the decalcification timing. The aim of this study is to determine and compare the decalcification of human articular cartilage and subchondral bone using EDTA together with ultrasonic cleaner or microwave oven. Hundred pieces of articular cartilage and subchondral bones obtained from osteoarthritis patients undergone total-knee-replacement were divided into 10 groups according to decalcification method (ultrasonic cleaner or microwave) and timing (2, 4, 6, 8, and 10 h). In each group, all cartilage and subchondral bone pieces were decalcified and sectioned, and subsequently stained with haematoxylin and eosin, Von Kossa, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, or caspase-3 immunohistochemistry. The optimal timing of decalcification of articular cartilage and subchondral bones using EDTA together with ultrasonic cleaner was at 8 and 10 h, while the timing using EDTA together with microwave oven was more than 10 h. Clear TUNEL and caspase-3 signals were obtained from samples decalcified using EDTA together with ultrasonic cleaner for 8 h. In summary, to our knowledge, this is the first study that compared EDTA decalcification between ultrasonic cleaner and microwave oven. Here, we report a new methodology for decalcification for articular cartilage and subchondral bones that reduces decalcification time from weeks to hours and is suitable for further pathological analyses.     

Recent advances in the understanding of molecular mechanisms of cartilage degeneration,synovitis and subchondral bone changes in osteoarthritis

Osteoarthritis (OA), the most common form of degenerative joint disease, is linked to high morbidity. It is predicted to be the single greatest cause of disability in the general population by 2030. The development of disease-modifying therapy for OA currently face great obstacle mainly because the onset and development of the disease involve complex molecular mechanisms. In this review, we will comprehensively summarize biological and pathological mechanisms of three key aspects: degeneration of articular cartilage, synovial immunopathogenesis, and changes in subchondral bone. For each tissue, we will focus on the molecular receptors, cytokines, peptidases, related cell, and signal pathways. Agents that specifically block mechanisms involved in synovial inflammation, degeneration of articular cartilage, and subchondral bone remodeling can potentially be exploited to produce targeted therapy for OA. Such new comprehensive agents will benefit affected patients and bring exciting new hope for the treatment of OA.     

Response of articular cartilage and subchondral bone to internal fixation devices made of poly- -lactide: a histomorphometric and microradiographic study on rabbits

To study the tissue response of articular cartilage and subchondral bone to biodegradable fixation devices, pins and rods made of poly- -lactide with a fibers-in-matrix texture were implanted through the articular surface of the intercondylar portion of the distal rabbit femur. The initial raw material viscosity average molecular weight of the polymer was 660,000. One pin or screw was implanted per animal. The pins were cylindrical and measured 4.5 mm in transverse diameter. The screws had a core diameter of 3.2 mm and an outer diameter of 4.5 mm. At insertion, the implants were cut flush with the articular surface. After follow-up times of 36 and 48 weeks, the specimens were examined histomorphometrically and microradiographically. The intact contralateral femur served as a control for comparison. No signs of erosion or degradation of the polymer could be seen in the specimens. A brim of reparative tissue was formed at the entrance of the implant channel. The width of the reparative tissue from the tissue–implant boundary towards the center of the entrance hole varied greatly between the specimens, from 30 to 950 μm. In most specimens this bridging tissue consisted of undifferentiated mesenchymal tissue. Only two out of 24 specimens showed a near-normal metachromatic toluidine-blue staining of the matrix. Degenerative chondrocyte clustering occurred in the pre-existing cartilage within a 400 μm wide zone from the tissue–implant interface into the recipient tissues. Some new-bone formation was seen to envelop the implant in all specimens, but the fractional osteoid formation surface of the trabeculae showed a value significantly higher than that of the intact control side only in the screw-implanted 36-week specimens. Because of the long degradation time of poly- -lactide, the restoration process of the articular cartilage was slow, and with regard to the quality and quantity of the reparative tissue, very variable. Large implants made of poly- -lactide may not be suitable for insertion through intra-articular surfaces.     

MMP-2、9在TRAP+单个核和多核细胞的表达及其在关节软骨损伤中的作用

目的:观察在胶原诱导的C57BL/6小鼠类风湿性关节炎(CIA)模型中,基质金属蛋白酶-2、9在耐酒石酸盐酸性磷酸酶(TRAP)阳性的单个核及多核细胞中的表达及其在关节软骨损伤中的作用。方法:注射鸡II型胶原免疫C57BL/6小鼠建立CIA模型。在CIA小鼠滑膜及滑膜软骨交界处,用酶组织化学及免疫组化染色分别检测TRAP 细胞的数量及细胞质内MMP的表达与软骨损伤的关系。结果:酶组织化学法检测表明TRAP 单个核及多核细胞增多的数量与CIA小鼠软骨的破坏程度呈正相关(rs=0.903,P<0.01)。免疫组化染色显示TRAP 细胞胞质内有MMP-2、9的表达,且表达的增多与CIA小鼠软骨的破坏程度呈正相关(rs=0.954,P<0.01)。结论:在CIA小鼠病变关节增生的滑膜组织及浸润到软骨表面的滑膜组织中的TRAP 单个核及多核细胞可表达MMP-2、9,表达的增多与软骨的破坏呈正相关,这些细胞在关节软骨的损伤中起到重要的作用。     

The micro and ultrastructural anatomy of bone spicules found in the osteochondral junction of bovine patellae with early joint degeneration

The structural changes in the tissues of the osteochondral junction are a topic of interest, especially considering how bone changes are involved in the initiation and progression of osteoarthritis (OA). Our research group has previously demonstrated that at the cement line boundary between the zone of calcified cartilage (ZCC) and the subchondral bone, in mature bovine patellae with early OA, there are numerous bone spicules that have emerged from the underlying bone. These spicules contain a central vascular canal and a bone cuff. In this study, we use high-resolution differential interference contrast optical microscopy and scanning electron microscopy to compare the cartilage–bone junction of three groups of mature bovine patellae showing healthy to mild to moderately degenerate cartilage. The ZCC and bone junction was carefully examined to estimate the frequency of marrow spaces, bone spicules and fully formed bone bulges. The results reveal that bone spicules are associated with all grades of cartilage tissue studied, with the most occurring in the intermediate stages of tissue health. The micro and ultrastructure of the bone spicule are consistent with that of an osteon, especially those found in compression zones in long bones. Also considering the coexistence of marrow spaces and fully formed bone, this study suggests that these bone spicules arise similar to the formation of osteons in the bone remodelling process. The significance of this conclusion is in the way researchers approach the bone formation issue in the early degenerative joint. Instead of endochondral ossification, we propose that bone formation in OA is more akin to a combination of primary bone remodelling and de novo bone formation.     

Development of articular cartilage and the metaphyseal growth plate: the localization of TRAP cells, VEGF, and endostatin

During long bone development the original cartilaginous model in mammals is replaced by bone, but at the long bone endings the avascular articular cartilage remains. Before the articular cartilage attains structural maturity it undergoes reorganization, and molecules such as vascular endothelial growth factor (VEGF) and endostatin could be involved in this process. VEGF attracts blood vessels, whereas endostatin blocks their formation. The present study therefore focused on the spatio-temporal localization of these two molecules during the development of the articular cartilage. Furthermore, we investigated the distribution of the chondro/osteoclasts at the chondro-osseous junction of the articular cartilage with the subchondral bone. Mice served as our animal model, and we examined several postnatal stages of the femur starting with week (W) 4. Our results indicated that during the formation of the articular cartilage, VEGF and endostatin had an overlapping localization. The former molecule was, however, down-regulated, whereas the latter was uniformly intensely localized until W12. At the chondro-osseous junction, the number of tartrate-resistant acid phosphatase (TRAP)-positive chondro/osteoclasts declined with increasing age. Until W3 the articular cartilage was not well organized but at W8 it appeared structurally mature. At that time only a few TRAP cells were present, indicative of a low resorptive activity at the chondro-osseous junction. Subsequently, we examined the metaphyseal growth plate that is closed when skeletal maturity is attained. Within its hypertrophic zone, localization of endostatin and VEGF was observed until W6 and W8, respectively. At the chondro-osseous junction of the growth plate, chondro/osteoclasts remained numerous until W12 to allow for its complete resorption. According to former findings, VEGF is critical for a normal skeleton development, whereas endostatin has almost no effect on this process. In conclusion, our findings suggest that both VEGF and endostatin play a role in the structural reorganization of the articular cartilage and endostatin may be involved in the maintenance of its avascularity. In the growth plate, however, endostatin does not appear to counteract VEGF, allowing vascular invasion of hypertrophic cartilage and bone growth.     

The thickness of the subchondral plate and its correlation with the thickness of the uncalcified articular cartilage in the human patella

The regional thickness distributions of the subchondral plate and the unmineralized part of the articular cartilage were morphometrically determined in normal human patellae, and the correlation coefficient for each specimen calculated from the paired measurements. For this purpose the patellae were embedded in methyl methacrylate and cut as serial sections, which were assessed with a Vidas image-analyzing system (Kontron). The values obtained were used to reconstruct the individual and average thickness distributions and to calculate the correlation coefficients for each subject. Both the thickness of the subchondral plate and that of the cartilage revealed regular distributions which, however, followed different patterns. Central regions with maximum values from which the thickness decreased concentrically towards the periphery were found in both. However, the distribution patterns of the unmineralized cartilage and the subchondral plate could be clearly distinguished, both by the position of the maxima and by the arrangement of the isocrassids (contour lines of equal thickness). The thicknesses of the two tissues showed a correlation between 0.38 and 0.82 (mean 0.6). We attribute this to their different reactions to the type of stress acting upon them. It appears that the thickness of the subchondral plate is principally determined by stresses acting over a longer period of time with low frequency, whereas the thickness of the articular cartilage seems to be a response to intermittent dynamic stresses of a higher frequency.     

累及骨和软骨Rosai–Dorfman病2例报告并文献复习

目的:探讨2例累及骨和软骨的结外罗道(Rosai–Dorfman)病的临床病理特征、诊断及鉴别诊断。方法:复习分别位于右胫骨近端及甲状软骨的2例Rosai–Dorfman病患者的临床和影像学资料,行组织学观察及免疫组织化学分析,并复习相关文献。结果:39岁女性,右胫骨占位及38岁男性,甲状软骨肿物。影像学示前者右胫骨上段溶骨性骨质破坏;CT示后者甲状软骨前实性占位,与甲状软骨界限不清。光镜下前者病变在破碎骨小梁间生长,后者病变包绕并侵犯甲状软骨,并在软骨化骨骨小梁间侵袭性生长。低倍镜下组织细胞显著增生,与浸润的淋巴细胞、浆细胞形成明暗相间的结构,部分组织细胞体积较大,呈多边形或椭圆形;胞浆淡嗜酸性或空亮,泡状核,可见小核仁;部分胞浆内见吞噬完整的淋巴细胞和(或)浆细胞、中性粒细胞等。免疫组织化学标记组织细胞表达S–100蛋白和CD68,不表达CD1a。结论:累及骨和软骨的Rosai–Dorfman病罕见,临床及影像学检查均容易误诊。组织学形态及免疫组织化学检查是确诊的唯一依据。     

Cell sources for the regeneration of articular cartilage: the past,the horizon and the future

Avascular, aneural articular cartilage has a low capacity for self‐repair and as a consequence is highly susceptible to degradative diseases such as osteoarthritis. Thus the development of cell‐based therapies that repair focal defects in otherwise healthy articular cartilage is an important research target, aiming both to delay the onset of degradative diseases and to decrease the need for joint replacement surgery. This review will discuss the cell sources which are currently being investigated for the generation of chondrogenic cells. Autologous chondrocyte implantation using chondrocytes expanded ex vivo was the first chondrogenic cellular therapy to be used clinically. However, limitations in expansion potential have led to the investigation of adult mesenchymal stem cells as an alternative cell source and these therapies are beginning to enter clinical trials. The chondrogenic potential of human embryonic stem cells will also be discussed as a developmentally relevant cell source, which has the potential to generate chondrocytes with phenotype closer to that of articular cartilage. The clinical application of these chondrogenic cells is much further away as protocols and tissue engineering strategies require additional optimization. The efficacy of these cell types in the regeneration of articular cartilage tissue that is capable of withstanding biomechanical loading will be evaluated according to the developing regulatory framework to determine the most appropriate cellular therapy for adoption across an expanding patient population.     

Deregulation of the CXCL12/CXCR4 axis in methotrexate chemotherapy-induced damage and recovery of the bone marrow microenvironment

Cancer chemotherapy disrupts the bone marrow (BM) microenvironment affecting steady-state proliferation, differentiation and maintenance of haematopoietic (HSC) and stromal stem and progenitor cells; yet the underlying mechanisms and recovery potential of chemotherapy-induced myelosuppression and bone loss remain unclear. While the CXCL12/CXCR4 chemotactic axis has been demonstrated to be critical in maintaining interactions between cells of the two lineages and progenitor cell homing to regions of need upon injury, whether it is involved in chemotherapy-induced BM damage and repair is not clear. Here, a rat model of chemotherapy treatment with the commonly used antimetabolite methotrexate (MTX) (five once-daily injections at 0.75 mg/kg/day) was used to investigate potential roles of CXCL12/CXCR4 axis in damage and recovery of the BM cell pool. Methotrexate treatment reduced marrow cellularity, which was accompanied by altered CXCL12 protein levels (increased in blood plasma but decreased in BM) and reduced CXCR4 mRNA expression in BM HSC cells. Accompanying the lower marrow CXCL12 protein levels (despite its increased mRNA expression in stromal cells) was increased gene and protein levels of metalloproteinase MMP-9 in bone and BM. Furthermore, recombinant MMP-9 was able to degrade CXCL12 in vitro. These findings suggest that MTX chemotherapy transiently alters BM cellularity and composition and that the reduced cellularity may be associated with increased MMP-9 expression and deregulated CXCL12/CXCR4 chemotactic signalling.     

Identification and location of bone-forming cells within cartilage canals on their course into the secondary ossification centre

Osteoblasts and osteocytes derive from the same precursors, and osteocytes are terminally differentiated osteoblasts. These two cell types are distinguishable by their morphology, localization and levels of expression of various bone cell-specific markers. In the present study on the chicken femur we investigated the properties of the mesenchymal cells within cartilage canals on their course into the secondary ossification centre (SOC). We examined several developmental stages after hatching by means of light microscopy, electron microscopy, immunohistochemistry and in situ hybridization. Cartilage canals appeared as extensions of the perichondrium into the developing distal epiphysis and they were arranged in a complex network. Within the epiphysis an SOC was formed and cartilage canals penetrated into it. In addition, they were successively incorporated into the SOC during its growth in the radial direction. Thus, the canals provided this centre with mesenchymal cells and vessels. It should be emphasized that regression of cartilage canals could never be observed in the growing bone. Outside the SOC the mesenchymal cells of the canals expressed type I collagen and periostin and thus these cells had the characteristics of preosteoblasts. Periostin was also expressed by numerous chondrocytes. Within the SOC the synthesis of periostin was down-regulated and the majority of osteoblasts were periostin negative. Furthermore, osteocytes did not secret this protein. Tissue-non-specific alkaline phosphatase (TNAP) staining was only detectable where matrix vesicles were present. These vesicles were found around the blind end of cartilage canals within the SOC where newly formed osteoid started to mineralize. The vesicles originated from osteoblasts as well as from late osteoblasts/preosteocytes and thus TNAP was only expressed by these cells. Our results provide evidence that the mesenchymal cells of cartilage canals express various bone cell-specific markers depending on their position. We suggest that these cells differentiate from preosteoblasts into osteocytes on their course into the SOC and consider that cartilage canals are essential for normal bone development within the epiphysis. Furthermore, we propose that the expression of periostin by preosteoblasts and several chondrocytes is required for adhesion of these cells to the extracellular matrix.     

Serum and synovial fluid concentrations of interleukin-18 and interleukin-20 in patients with osteoarthritis of the knee and their correlation with other markers of inflammation and turnover of joint cartilage

IntroductionOsteoarthritis (OA) is the most common degenerative joint disease, and its aetiology is not entirely known. The aim of the study was to evaluate the involvement of interleukin-18 (IL-18) and interleukin-20 (IL-20) in the pathogenesis of knee OA and their correlations with other markers of inflammation and destruction of joint cartilage, as well as clinical and radiological changes.Material and methodsThe study included 25 patients with knee OA and a control group. The concentration of IL-18, IL-20, IL-6, MMP-1, MMP-3, COMP, PG-AG, and YKL-40 in serum and synovial fluid (SF) were determined. We also evaluated radiological lesions of the knee joint according to the Kellgren-Lawrence (K-L) scale, and clinical severity of the disease according to Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Lequesne Index.ResultsThe concentrations of IL-18 and IL-20 were statistically significantly higher in serum of patients with OA than in the control group (106.00 ±189.76 pg/ml vs. 16.73 ±16.99 pg/ml, p < 0.001, 17.69 ±13.45 pg/ml vs. 9.76 ±9.00 pg/ml, p < 0.014). Serum concentration of IL-18 positively correlated with MMP-3 (R = 0.58; p = 0.006) and YKL-40 (R = 0.48; p = 0.002). The degree of radiological advancement of OA (K-L scale) correlated positively with clinical evaluation (WOMAC, R = 0.74, p ≤ 0.001; Lequesne Index, R = 0.57, p = 0.003).ConclusionsThe analysis of ROC curves showed that IL-20 as well as COMP, MMP-3, and YKL-40 may be diagnostic markers of knee OA. The observations indicate that IL-18 potentially mediates mainly in intra-articular processes and IL-20 could be primarily responsible for the systemic inflammatory reaction.