Thioredoxin gene expression in rat knee articular cartilage after full-thickness injury

To study the expression of the antioxidative protein thioredoxin (TRX) in intact and injured articular cartilage, we examined the presence of trx mRNA in rat knee joints by in situ hybridization. Our results showed that in the intact knee, most cells, including articular cartilage chondrocytes, expressed trx mRNA. We examined joints at 1, 7, 14, and 28 days after the infliction of full-thickness cartilage injuries on distal femoral condyles. At 1 day after injury, no significant changes were observed in the wound or in trx expression pattern. However, at 7 to 28 days after injury, the wound became filled with repair tissue. Also, trx expression was detected in differentiating mesenchymal cells in the deeper zones of the wound but not in fibroblast-like cells in the upper part of the repair tissue, toward the joint cavity. This lack of TRX expression in the fibroblast-like cells may underlie the susceptibility of the repair tissue fibrocartilage to oxidative stress.     

LY-294002对大鼠骨关节炎模型关节软骨中VEGF表达的影响

目的研究LY-294002对大鼠骨关节炎模型关节软骨中血管内皮生长因子(VEGF)表达的影响。方法健康雄性Wistar大鼠30只,随机分为对照组、骨性关节炎组(OA组)和LY-294002治疗组,每组10只。利用膝关节注射4%的木瓜蛋白酶溶液的方法制作骨关节炎模型。采用关节炎评分法评定各组大鼠平均关节炎指数(MAI),Western blot方法检测关节软骨中VEGF蛋白的表达变化,RT-PCR方法检测VEGF m RNA的表达变化。结果对照组关节无任何异常变化,OA模型组随着造模的时间延长,关节出现了重度红肿现象,与OA模型组比较,给药组的关节炎症反应呈现消退现象。术后8周检测关节软骨中VEGF蛋白及m RNA表达的变化,结果显示VEGF蛋白及m RNA在对照组大鼠关节软骨仅有微量表达,而在OA组大鼠关节软骨表达则显著升高(P0.01);与OA组相比,LY-294002治疗组大鼠关节软骨中VEGF蛋白及m RNA表达均显著降低(P0.01)。结论下调VEGF的表达很可是LY-294002参与骨关节炎的发病机制之一。     

Structure and regulation of articular cartilage proteoglycan expression]

Beyond aggrecan, the major proteoglycan present in articular cartilage that confers resistance to compressive load and viscoelasticity to the tissue, other proteoglycan families have been described in cartilage. Among them, decorin, biglycan and fibromodulin which belong to the small leucine-rich proteoglycans family bind to matrix components, specially to collagen fibrils and thus regulate fibrillogenesis in cartilage and matrix integrity. These small proteoglycans can also interact with TGF-beta and modulate its bioavailability and stability. The third family is composed by cell surface proteoglycans as syndecans, glypican-1 and betaglycan. These molecules interact with various components of cell environment (growth factors, proteases, matrix components, etc.) and mediate numerous cell functions. Some modifications of one of these proteoglycan expression occur during degenerative pathologies and may lead to alteration of the functional properties of the tissue as well as variations in growth factor bioavailability. These factors are involved in the attempt of cartilage repair initiated by chondrocytes in the early stages of osteoarthritis.     

环氧合酶-2抑制剂对大鼠骨关节炎模型软骨中血管内皮生长因子表达的影响

目的研究环氧合酶-2抑制剂(吲哚美辛)对大鼠骨关节炎模型关节软骨中血管内皮生长因子(VEGF)表达的影响。方法健康雄性wistar大鼠30只,随机均分为对照组、骨性关节炎组(OA组)和吲哚美辛处理组。利用膝关节注射4%的木瓜蛋白酶溶液的方法制作骨关节炎模型。采用关节炎评分法评定各组大鼠平均关节炎指数(MAI),免疫组化方法与Western blot方法检测关节软骨中VEGF蛋白的表达变化。结果 OA模型组随着造模的时间延长,关节出现了重度红肿现象,对照组关节无任何异常变化;与OA模型组比较,吲哚美辛组的关节炎症反应呈现消退现象。VEGF蛋白在对照组大鼠关节软骨仅有微量表达,而在术后8周OA组大鼠关节软骨表达则显著升高(P0.01);与OA组相比,吲哚美辛组大鼠关节软骨中VEGF蛋白表达显著降低(P0.01)。结论吲哚美辛对骨关节炎的抑制作用可能与下调VEGF蛋白的表达相关。     

Stromelysin expression in IL-1β stimulated bovine articular cartilage explants

Inflammation Research -     

Engineering lubrication in articular cartilage

Despite continuous progress toward tissue engineering of functional articular cartilage, significant challenges still remain. Advances in morphogens, stem cells, and scaffolds have resulted in enhancement of the bulk mechanical properties of engineered constructs, but little attention has been paid to the surface mechanical properties. In the near future, engineered tissues will be able to withstand and support the physiological compressive and tensile forces in weight-bearing synovial joints such as the knee. However, there is an increasing realization that these tissue-engineered cartilage constructs will fail without the optimal frictional and wear properties present in native articular cartilage. These characteristics are critical to smooth, pain-free joint articulation and a long-lasting, durable cartilage surface. To achieve optimal tribological properties, engineered cartilage therapies will need to incorporate approaches and methods for functional lubrication. Steady progress in cartilage lubrication in native tissues has pushed the pendulum and warranted a shift in the articular cartilage tissue-engineering paradigm. Engineered tissues should be designed and developed to possess both tribological and mechanical properties mirroring natural cartilage. In this article, an overview of the biology and engineering of articular cartilage structure and cartilage lubrication will be presented. Salient progress in lubrication treatments such as tribosupplementation, pharmacological, and cell-based therapies will be covered. Finally, frictional assays such as the pin-on-disk tribometer will be addressed. Knowledge related to the elements of cartilage lubrication has progressed and, thus, an opportune moment is provided to leverage these advances at a critical step in the development of mechanically and tribologically robust, biomimetic tissue-engineered cartilage. This article is intended to serve as the first stepping stone toward future studies in functional tissue engineering of articular cartilage that begins to explore and incorporate methods of lubrication.     

Type IIA procollagen: expression in developing chicken limb cartilage and human osteoarthritic articular cartilage.

Type IIA procollagen is an alternatively spliced product of the type II collagen gene and uniquely contains the cysteine (cys)-rich globular domain in its amino (N)-propeptide. To understand the function of type IIA procollagen in cartilage development under normal and pathologic conditions, the detailed expression pattern of type IIA procollagen was determined in progressive stages of development in embryonic chicken limb cartilages (days 5-19) and in human adult articular cartilage. Utilizing the antibodies specific for the cys-rich domain of the type IIA procollagen N-propeptide, we localized type IIA procollagen in the pericellular and interterritorial matrix of condensing pre-chondrogenic mesenchyme (day 5) and early cartilage (days 7-9). The intensity of immunostaining was gradually lost with cartilage development, and staining became restricted to the inner layer of perichondrium and the articular cap (day 12). Later in development, type IIA procollagen was re-expressed at the onset of cartilage hypertrophy (day 19). Different from type X collagen, which is expressed throughout hypertrophic cartilage, type IIA procollagen expression was transient and restricted to the zone of early hypertrophy. Immunoelectron microscopic and immunoblot analyses showed that a significant amount of the type IIA procollagen N-propeptide, but not the carboxyl (C)-propeptide, was retained in matrix collagen fibrils of embryonic limb cartilage. This suggests that the type IIA procollagen N-propeptide plays previously unrecognized roles in fibrillogenesis and chondrogenesis. We did not detect type IIA procollagen in healthy human adult articular cartilage. Expression of type IIA procollagen, together with that of type X collagen, was activated by articular chondrocytes in the upper zone of moderately and severely affected human osteoarthritic cartilage, suggesting that articular chondrocytes, which normally maintain a stable phenotype, undergo hypertrophic changes in osteoarthritic cartilage. Based on our data, we propose that type IIA procollagen plays a significant role in chondrocyte differentiation and hypertrophy during normal cartilage development as well as in the pathogenesis of osteoarthritis.     

模拟微重力对大鼠关节软骨力学特性的影响

目的基于大鼠尾吊实验,研究模拟微重力对关节软骨组织力学特性的影响。方法通过14 d的尾吊实验建立模拟微重力作用的大鼠模型,获得12块后肢大腿骨关节处软骨样本,运用高频超声测量技术获取大鼠关节软骨特定位置因自由膨胀引起的组织应变,基于三相模型估计软骨组织的轴向弹性模量,并比较尾吊组和对照组大鼠关节软骨的力学特性。结果尾吊组大鼠后肢特定测量位置处软骨厚度的平均值略小于对照组,但差异不显著;尾吊组大鼠特定位置关节软骨组织的平均轴向弹性模量为(5.05±2.98)MPa,小于对照组((6.31±3.37)MPa),两者存在着显著差异(P<0.05)。结论微重力环境会影响关节软骨组织的力学特性,本研究结果为人类长期的太空活动提供参考信息。     

The effect of spinal cord injury on the expression of TGF-β and TNF-α in rat articular cartilage

Objective: To observe the expression of TGF-β and TNF-α in the spinal cord injured rat model and discuss the significance of the articular cartilage metabolism. Methods: 36 SD female rats were randomly divided into 2 groups: Rats models of spinal cord injury were implemented by Allen method. T10 laminectomy was performed in the control group. Both groups of rats were killed respectively in 1w, 3w and 6w. Hematoxylin-eosin stain was given to each slice in the model group and control group. Immunohistochemical stain was applied by using ABC method in the expression of TGF-β and TNF-α. Those expressed level were performed in image analysis and statistics process. Results: TGF-β and TNF-α were mainly distributed on the surface layer of the articular cartilage, with a weak expression in control group. The expression of TNF-α in the model group was more significant than that in the control group in the 1w, and still remained an evident difference with that in control group until the 6w(P ＜ 0.05). TGF-β expression of the model group had no remarkable difference with the control group in the lw (P ＞ 0.05) and prominently became stronger at 6w(P ＜ 0.05). Conclusion: The expression of TNF-o occurred early in the development of spinal cord injury, and the expression of TGF-β became stronger with the revival of spinal neural function. Both expressions were strengthened in articular cartilage in the 3rd week.     

Morphology of articular cartilage in osteoarthrosis

A combined histological, histochemical, histoenzymochemical and morphometric study of 42 articular cartilage samples from patients with different degrees of osteoarthrosis (OA) was made. Ten cartilages without pathology taken at autopsy were used as controls. A characteristic feature in case of cartilage destruction by OA is a progressive loss of glycosaminoglycans (GAG) from the matrix with its defibrination and uzur formation. Decrease in GAG content is associated with partial destruction of chondrocytes and the emergence of cellular clones reflecting reparative regeneration of the cartilage. However, even at the early OA stage the reparation is not adequate, as the GAG content in the matrix at the sites of chondrocyte proliferation remains decreased compared to the control age group.     

The stress-structure relationship in articular cartilage

The results of a theoretical analysis of the stress distribution in load-bearing articular cartilage are presented in a graphical form. They are used to examine the theory which presumes collagenous fibres to be arranged in the most suitable position for supporting the tensile stresses set up in articular cartilage. This examination seems to indicate that the orientations of the superficial fibres follow the lines of the tensile stress trajectories very closely, whereas the suggested arrangement of the deeper fibres is generally inconsistent with mechanical conditions.     

关节软骨组织工程的研究进展

介绍了关节软骨组织工程中种子细胞、支架材料的研究现状以及生长因子在关节软骨组织工程中的应用进展，阐明了随着对细胞行为、支架材料特性、细胞与材料的组合构建研究的深入，组织工程在关节软骨修复方面应用前景十分广阔。     

组织工程化软骨修复关节软骨缺损

背景：目前治疗软骨缺损的方法均有明显缺陷,组织工程软骨修复关节软骨缺损为微创治疗软骨缺损提供了新方法。 目的：总结组织工程软骨应用于修复关节软骨缺损的新进展。 方法：由第一作者用计算机检索万方数据库(2000/2010)和PubMed数据库(2000/2010),检索词分别为“软骨缺损,组织工程软骨”和“articular cartilage defects, tissue-engineered cartilage”,语言分别设定为中文和英文。从组织工程软骨及其新进展2方面进行总结,对组织工程软骨的发展及构建等方面进行介绍。共检索到666篇文献,按纳入和排除标准对文献进行筛选,共纳入23篇文章。 结果与结论：近年来随着细胞支架材料的不断发展和组织构建技术的日趋成熟,结合活性细胞和支架的组织工程软骨为微创修复关节软骨缺损提供了良好的治疗手段及方法,组织工程软骨修复软骨缺损是完全可行的,C-GP凝胶与种子细胞相容性好,可做为组织工程软骨的理想支架,但细胞支架的制备及选择仍然是组织工程软骨的热点和难点。     

Mechanical impact and articular cartilage

Mechanical impact forces on articular cartilage can cause substantial damage. Car accidents, falls, and sports injuries have a tremendous effect on the U.S. and world populations, both in terms of economic and quality of life costs. While the effects of impact forces are known to be damaging, tolerance levels of cartilage to these forces and the mechanobiologic sequelae are still mostly unknown. Impact studies can be difficult to compare to each other due to the complex array of mechanical factors that are involved in a single impact. Previous work includes mathematical models, acute effects of impact, and in vivo and explant models of impact. These experiments have found that articular cartilage has a threshold above which impact forces are damaging, though this threshold is likely dependent on many factors, both genetic and environmental. This type of damage has been shown to vary according to the severity of the impact, from leaving the articular cartilage surface intact to fracture of the subchondral bone. Some studies have initiated investigations into ways to ameliorate the injurious response to impact, which may allow some patients to avoid the ensuing cartilage degeneration and osteoarthritis. Much work remains to be performed in understanding the genetic and biochemical response to impact. The goal of this research is to eventually decrease the incidence of posttraumatic arthritis and possibly even delay primary osteoarthritis, which can be achieved by using a robust testing design that includes morphological, biomechanical, quantitative biochemical, and genetic characterization of a model system for articular cartilage impact. This model system can then be used to test treatments to prevent degenerative changes in articular cartilage.     

Stress-lowering function of articular cartilage

Nine cadaver human hips were loaded cyclically in a physiological direction and to maxima of about three times body weight. Deformations of the whole joint and of the cartilage only were measured. The tests were repeated after all cartilage had been removed. Hips with normal cartilage showed no permanent deformation after up to 2000 cycles of load, whereas hips with degenerate cartilage showed irrecoverable deformation in the bone. Loading after removal of cartilage produced permanent deformation, accompanied by fatigue cracks, in the bone of all joints. It is concluded that normal cartilage limits the stresses in subchondral bone to a safe level whereas degenerate cartilage does not.     

关节软骨的修复与修复失败

文题释义： 自体软骨细胞移植：对于3.5-10 cm2的软骨缺损或多个缺损来说,自体软骨细胞移植是一种有效的软骨修复措施,取少量患者自体软骨于体外培养软骨细胞,并增殖到一定数量后植入软骨缺损处,从而达到修复缺损的目的。 基质诱导的自体软骨细胞移植：把经培养增殖后的软骨细胞接种到Ⅰ/Ⅲ型双层胶原膜上,继续培养数日,细胞与支架结合紧密之后,使用生物蛋白胶粘贴到关节软骨缺损病灶底部。术后,软骨细胞从胶原膜上游离并穿过生物胶,迁徙到软骨缺损的基底部。胶原膜和生物胶逐步降解并被吸收。接种的软骨细胞在局部生长、繁殖,并分泌基质,形成新的软骨组织修复缺损。背景：由于关节软骨具有复杂的生物学特性和高度的耐用性,自然退变或创伤引起的缺损都可能导致其结构和功能上不可逆的损害,因此关节软骨损伤后的修复治疗是临床上急需解决的问题。 目的：报告关节软骨修复技术失败最常见的危险因素及其发生率,分析影响选择特定手术治疗方法来处理软骨修复失败最重要的因素。 方法：以“articular cartilage, repair, clinic/clinical failure, surgery”为检索词,检索 PubMed和MEDLINE数据库,时限为2007至2019年,语言限制为英文。初检得到文献约343篇,根据纳入排出标准筛选,共纳入38篇文章进行分析。 结果与结论：①微骨折术和软骨镶嵌成形术在关节软骨修复后的前期和中期显示出不可忽视的失败率,而使用自体软骨细胞移植和异体骨软骨移植修复关节软骨的效果更好。②对于软骨修复失败的治疗：在以往软骨修复失败的患者中应用异体骨软骨移植可能是一个安全的选择,但对于失败的异体骨软骨移植的修复则有更高的失败率;而既往自体软骨细胞移植或基质诱导的自体软骨细胞移植失败的患者,经进一步的自体软骨细胞移植或基质诱导的自体软骨细胞移植治疗后,其治疗效果是可以接受的。此外,有软骨下骨髓刺激病史的患者,自体软骨细胞移植的失败率更高。③软骨修复失败的处理取决于手术治疗失败的类型以及软骨缺损的面积、部位的不同,异体骨软骨移植是治疗软骨下骨髓刺激患者软骨修复失败的最可靠的方法,而自体软骨细胞移植或基质诱导的自体软骨细胞移植在既往软骨修复失败的患者中显示出可以接受的治疗效果,在处理软骨修复失败的患者时,应该特别注意软骨下骨质的情况。ORCID: 0000-0002-3907-9145(张宇) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

The auto-immunogenicity of articular cartilage

Rats injected with syngeneic chondrocytes or cartilage shavings develop autoreactivity as assayed by the leucocyte migration inhibition test. It is suggested that chondrocyte specific differentiation antigen(s), normally sequestered from the immune system, once exposed experimentally by enzyme treatment or in some human pathological situations are recognized as foreign immunogens and induce a lymphocyte response.     

Gene expression profiling of human articular cartilage grafts generated by tissue engineering

Cartilage tissue engineering is applied clinically to cover and regenerate articular cartilage defects. In this study autologous human cartilage tissue engineering grafts based on bioresorbable polyglactin/polydioxanone scaffolds were analyzed on the broad molecular level. RNA from freshly isolated, primary and expanded adult articular chondrocytes and from three-dimensional cartilage grafts were used for gene expression profiling using oligonucleotide microarrays. The capacity of cartilage grafts to form cartilage matrix was evaluated after subcutaneous transplantation into nude mice. Gene expression profiling showed reproducibly the regulation of 905 genes and documented that chondrocytes undergo fundamental changes during cartilage tissue engineering regarding chondrocyte metabolism, growth, and differentiation. Three-dimensional assembly of expanded, dedifferentiated chondrocytes initiated the re-differentiation of cells that was accompanied by the reversal of the expression profile of multiple players of the transforming growth factor (TGF) signaling pathway including growth and differentiation factor-5 and inhibitor of differentiation-1 as well as by the induction of typical cartilage-related matrix genes such as type II collagen and cartilage oligomeric matrix protein. Cartilage grafts formed a cartilaginous matrix after transplantation into nude mice. Three-dimensional tissue culture of expanded articular chondrocytes initiates chondrocyte re-differentiation in vitro and leads to the maturation of cartilage grafts towards hyaline cartilage in vivo.