An experimental model for hydrogen peroxide induced tissue damage: effect on cartilage and other articular tissues

Hydrogen peroxide is a mediator of inflammation capable of damaging several cell types and biomolecules at relatively low concentrations in vitro. In order to evaluate the destructive potential of hydrogen peroxide in vivo, we devised an arthritis model in which hydrogen peroxide is initially the sole mediator of inflammation. Cationic glucose oxidase was injected intra-articularly into mouse knee joints. This enzyme produces hydrogen peroxide, using endogenous glucose as a substrate; thus a severe monoarthritis which lasts for several weeks can be induced. The contralateral joint is used as a control. Using histology and measurement of 99mTechnetium uptake we demonstrated severe oedema formation, damage to ligaments, muscles and cartilage, and infiltration of the tissue by inflammatory cells. These effects could be inhibited by the intraarticular administration of catalase. The effect of hydrogen peroxide on cartilage damage was shown to be reversible at low doses of glucose oxidase. This model shows what type of lesions can be induced by hydrogen peroxide generation in vivo. In addition we deem this model to be useful for studying chronic degenerative processes and for screening drugs that can scavenge hydrogen peroxide. The relevance of oxygen metabolites as inflammatory mediators is discussed.     

Effect of hydrogen peroxide on the metabolism of articular chondrocytes

OBJECTIVE: To examine the effect of hydrogen peroxide on chondrocyte metabolism. MATERIALS AND METHODS: Bovine articular chondrocytes were used. Proteoglycan (PG) synthesis was measured with [35S] sulfate incorporation. For detection of apoptosis, the TdT-mediated dUTP-biotin nick end labeling (TUNEL) and annexin V assay were used. Extracellular-regulated protein kinase (ERK) activity was measured using a mitogen-activated protein kinase assay system. RESULTS: Addition of hydrogen peroxide resulted in the inhibition of PG synthesis, apoptosis, and enhanced ERK activity. CONCLUSION: Hydrogen peroxide plays an important role in regulating the metabolism of chondrocytes.     

Degradation of phospholipid polymer hydrogel by hydrogen peroxide aiming at insulin release device

The purpose of this study is to ascertain the applicable possibility of H₂O₂ degradable hydrogel for fabrication of insulin release system synchronized with the change in the glucose concentration in the medium. The hydrogel was prepared by using 2-methacryloyloxyethyl phosphorylcholine (MPC) and crosslinker. The favorable characteristic of the hydrogel was H₂O₂ concentration responsive degradation. The H₂O₂ was utilized and produced by enzymatic reaction between glucose oxidase and glucose. Poly(MPC) (PMPC) was easily degraded in H₂O₂ aqueous solution, and the PMPC hydrogel was also degraded in H₂O₂ aqueous solution. The degradation mechanism was considered to be main chain scission of PMPC. The degradation profile was evaluated by using weight swelling ratio and volume swelling ratio. The weight swelling ratio of PMPC hydrogel firstly increased due to the reduction of crosslink density, then the ratio decreased to zero (complete degradation). The degradation profile was proportional to the H₂O₂ concentration. Furthermore, volume swelling ratio also increased, and complex elastic modulus decreased with degradation in H₂O₂ aqueous solution. These results indicated that the hydrogel was degraded by hydroxy and/or hydroperoxy radicals which was produced by H₂O₂, the crosslink density and mechanical property decreased. The release profile from the hydrogel was estimated by using lipid microsphere (LM) as an insulin model. The LM was released with the degradation of PMPC hydrogel. Taking these results into account, the PMPC hydrogel was available for H₂O₂ degradable hydrogel for synchronization with glucose concentration by using enzymatic reaction.     

Berakdown of articular cartilage by vascular tissue

A study has been made with porcine tissues in organ culture of th effect of vascular tissue on articular cartilage. Isolated explants of cartilage were maintained alive for 14 days without breakdown of the matrix. Contact with vascular tissue produced extensive loss of proteoglycan and collagen wth fibroblastic transformaton of te chondrocytes. The breakdown was partly dur to a direct effect on te matrix and partly to activation of catabolic processes in the chondrocytes. Vascular tissue produced exactly the same loss of matrix as synovial tissue.     

Degradation of human cartilage by monocytes

The effect of human peripheral blood monocytes on the degradation of human articular cartilage was studied in vitro using a radiometric assay to detect proteoglycan breakdown. The results showed that proteoglycan breakdown was increased by 60% after a 20 h exposure to monocytes (p less than 0.001).     

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.     

Repair of articular cartilage defect by cell transplantation

Full-thickness articular cartilage defects are a major clinical problem; however, at present there is no treatment that is widely accepted to regeneratively repair these lesions. The current therapeutic approach is to drill or abrade the base of the defect to expose the bone marrow with its cells and growth factors. This usually results in a repaired tissue of fibrocartilage that functions poorly in the loaded joint environment. Recently, autologous cultured chondrocyte transplantation and mosaic plasty were explored. We can repair small articular cartilage defects using these methods, although their effectiveness is still controversial. We have reported that transplantation of allogeneic chondrocytes embedded in collagen gels or allogeneic chondrocytes cultured in collagen gels could repair articular cartilage defect in a rabbit model. We also reported that autologous culture-expanded bone marrow mesenchymal cell transplantation could repair articular cartilage defect in a rabbit model. This procedure offers expedient clinical use, given that autologous bone marrow cells are easily obtained and can be culture-expanded. We transplanted autologous culture-expanded bone marrow cells into the cartilage defect of the osteoarthritic knee joint on 11 patients at the time of high tibial osteotomy. As early as 6.8 weeks after transplantation, the defect was covered with white soft tissue, in which slight metachromasia was histologically observed. Thirty-three weeks after transplantation, the repaired tissue had hardened. Histologically, repaired tissues showed stronger metachromasia and a partial hyaline cartilage-like appearance. This procedure may prove a promising method by which to repair articular cartilage defects.     

Breakdown of articular cartilage proteoglycans by lymphokine-activated macrophages

Lymphokine supernatants (L_E) prepared from antigen sensitive lymphocytes caused an inhibition of migration of macrophages from capillary tubes. Control supernatants (L_C) had no effect. The lymphokine supernatants, when added to macrophage cultures (the equivalent of 60 × 10⁶ lymphocytes added to 40×l0⁶ macrophages), activated the macrophages so that they secreted the enzyme collagenase after 48 h and 72 h of culture. No collagenase was detected before 48 h or from macrophage supernatants to which L_C was added. The macrophage supernatants (L_E but not L_C) also contained factors (probably enzymes) that, when added to a piece of articular cartilage in medium, caused a partial loss of the hexosamine content of the articular cartilage. These changes were seen as early as after 24 h of culture. Activated macrophages therefore release enzymes that can completely destroy cartilage. Both collagenase and a proteoglycan-hydrolyzing enzyme are released which in vivo might be responsible for the cartilage damage that is found in diseases such as rheumatoid arthritis.     

关节软骨缺损的组织工程修复

背景：软骨组织工程主要由种子细胞、生物支架、生长因子3方面组成,如何完善软骨组织工程修复一直是科研工作者研究的重点。 目的：全面了解应用软骨组织工程修复软骨损伤的研究现状。 方法：计算机检索PubMed和CNKI数据库中2005/2010相关文献。以“Cartilage, tissue engineering, repair”或“关节软骨、组织工程、修复”为检索词进行检索。纳入与软骨组织工程密切相关的文献,排除重复性研究。 结果与结论：共检索到167篇文献,排除无关重复的文献,保留20篇文献进行综述。研究认为种子细胞是软骨组织工程最关键的方面,包括软骨细胞、骨髓间充质干细胞、胚胎干细胞和通过基因工程得到的种子细胞。目前应用最多、应用前景最好的是骨髓间充质干细胞。生物支架经历了一个漫长的过程,趋向于复合性和功能性的方向发展。各种生长因子在组织工程中必不可少。转化生长因子、胰岛素样生长因子、骨形态发生蛋白等在软骨修复中发挥了重要的功能。     

Regulation of translation by hydrogen peroxide

Cells must be able to maintain their intracellular homeostasis in the face of changing conditions. Typically, they respond by invoking complex regulatory mechanisms, including a global inhibition of translation. This reduction in protein synthesis may prevent continued gene expression during potentially error-prone conditions as well as allow for the turnover of existing mRNAs and proteins, whilst gene expression is directed toward the production of new molecules required to protect against or detoxify the stress. However, it is becoming increasingly recognized that not all translation is inhibited and translational control of specific mRNAs is required for survival under stress conditions. Control of protein levels via translational regulation offers a significant advantage to the cell due to the immediacy of the regulatory effect. This review describes how protein synthesis is regulated in response to oxidative stress conditions induced by exposure to hydrogen peroxide. Translational control can be mediated via direct oxidative regulation of translation factors as well via mRNA-specific regulatory mechanisms. Additionally, increasing evidence suggests that oxidative damage to the translational apparatus can itself alter the proteomic output. The resulting translational reprogramming is fundamental for adaptation to the oxidative stress.     

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。     

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.