异常高应力导致关节软骨退变机理的形态学研究

通过透射电镜、扫描电镜和光镜，对８７只跟腱切除的ＳＤ大鼠的对侧膝关节软骨进行了观察。发现术后２周，关节软骨表面出现凹陷与裂隙；术后１个月，软骨出现软骨细胞簇，软骨细胞显示旺盛的合成与分泌功能。继而，关节软骨进行性地退变。高应力首先导致软骨基质的破坏，使胶原纤维网架断裂，蛋白多糖丧失。基质破坏使正常的微环境发生变化，导致软骨细胞的退变。软骨细胞退变又可加重基质的损害，形成恶性循环。高应力造成软骨基质损害的早期可引起部分软骨细胞增生，并具有活跃的合成、分泌功能，但随后大部分细胞退变。这是最初的基质损害激发了软骨细胞的修复功能，但随着基质损害的加重，正常微环境遭到破坏，又使这些细胞也迅速退变。     

应力导致关节软骨退变机制的实验研究

目的　本实验的目的是探讨应力导致关节软骨退变的病理过程与生物力学机制。方法　以 32只中国白兔为实验对象 ,在关节面施以持续高 低压应力 ,观察 4、12周 ,用组织学、组织化学、免疫组化及透射电镜为方法 ,分析退变软骨。结果　低压应力引起的退变首先表现为早期软骨细胞功能减退 ,软骨细胞代偿增生反应轻 ,然后基质破坏 ,最终导致整个软骨退变。高压应力引起的退变首先是早期基质破坏 ,软骨细胞代偿增生同时发生 ,继而软骨细胞退变 ,最终整个关节软骨退变。细胞因子主要在退变软骨的浅、移行层软骨细胞胞浆内阳性染色 ,偶可在浅层细胞近周及裂隙处见基质阳性染色。结论　高、低压应力均可导致关节软骨退变 ,低压应力首先引起软骨细胞退变 ;高压应力首先引起基质破坏。退变软骨的软骨细胞可异常合成、分泌细胞因子 ,细胞因子在软骨退变中发挥作用。     

射频能量治疗关节软骨损伤研究现状

急性外伤、关节退变引起关节软骨损伤逐年递增,目前尚无一种理想的治疗方法.近年射频能量技术已广泛应用于治疗关节软骨损伤,但存在争议.该文综述射频能量治疗软骨损伤的体内或体外基础研究及临床研究,分析不同射频装置、射频能量、处理时间对关节软骨细胞活力、组织形态学、生物化学或生物力学的影响,以及温度和灌洗液对关节软骨的影响.     

不同模式高强度运动训练对兔膝关节软骨组织病理学的影响

目的研究不同模式高强度运动训练对关节软骨组织病理学方面的影响，了解不同运动所致关节软骨过劳性损伤的病变始动因素及病理特点。方法40只新西兰大白兔随机分为三组：对照组（8只）、跑步组（16只）以及蹦跳组（16只）。跑步组与蹦跳组动物每日分别施行高强度跑步与蹦跳训练。实验动物分别于训练4、8周时处死取材。膝关节软骨做病理组织学检查，分别行光电镜显微观察以及葡萄糖胺聚糖（GAG）、关节软骨及软骨下骨厚度、坏死细胞率、Mankin病理学评分等检测。结果显微观察显示两组训练动物在训练4周时便开始有膝关节软骨过劳性损伤早期改变，8周时损伤改变进一步加重。4周时，蹦跳组GAG含量明显低于对照组及跑步组，跑步组死亡细胞率明显高于对照组以及蹦跳组，跑步组和蹦跳组Mankin评分明显高于对照组；8周时，跑步组GAG含量明显低于对照组，死亡细胞率与Mankin评分明显高于对照组。蹦跳组GAG含量、软骨下骨厚度明显低于对照组，死亡细胞率与Mankin评分明显高于对照组。跑步组与蹦跳组在GAG含量与坏死细胞率间差异有统计学意义（P〈0．05）。结论较长时间高强度的蹦跳与跑步运动均容易产生关节软骨运动性损伤。跑步运动所致损伤早期多表现为软骨细胞损伤，而蹦跳运动则以基质流失为主要表现。     

前交叉韧带断裂和重建对膝关节软骨退变影响的实验研究

目的：研究前交叉韧带（ACL）断裂和不同时期重建对膝关节软骨继发损伤的影响。方法：以新西兰大白兔为实验对象,共14只。共分4组,每组7个膝关节,实验组Ⅰ：右膝前交叉韧带切断后随即重建,左膝的前交叉韧带切断后不予重建作为对照组Ⅰ;组Ⅱ：右膝前交叉韧带切断后3周重建,左膝行单纯关节切开术作为对照组Ⅱ。术后8周通过墨汁染色,常规组织学及扫描电镜方法观察各组膝关节软骨退变的情况。结果：（1）实验组Ⅰ关节软骨退变程度明显轻于对照组Ⅰ（Hc=5.9889,P=0.0144);(2)实验组Ⅱ关节软骨退变程度和对照组Ⅰ相比差异无显著性意义（Hc=0.7143,P=0.785)。结论：（1）ACL断裂后即刻重建可以有效阻止关节软骨继发损伤的发生;（2）ACL断裂后已继发关节软骨退变时再行重建,其对关节软骨退行性变的缓解作用不明显。ACL 裂后应进行早期重建,恢复膝关节稳定性,减少或延缓远期骨性关节炎的发性。     

射频能量在治疗关节软骨面不平中对软骨细胞及基质的作用

射频技术在关节软骨成形手术中的应用日益广泛。关节软骨缺乏神经、血管及淋巴系统,关节软骨受损后自身修复能力有限,射频治疗产生的热量可能对软骨细胞及基质有损伤效应。射频能量在软骨成形术中的安全性目前尚无一致意见。该文作者模拟在关节镜条件下采用射频技术,分析蛋白多糖的合成与降解的程度,检测细胞的存活能力。观察不同射频能量对软骨细胞及基质的损伤效应。采用马的新鲜髌骨11对,以骨挫造成软骨面部分厚度的     

基质诱导自体软骨细胞移植修复膝关节软骨损伤的早期疗效

目的探讨基质诱导自体软骨细胞移植修复膝关节软骨损伤的早期疗效。方法基质诱导自体软骨细胞移植修复50例膝关节软骨损伤患者,全程关注治疗情况。结果患者均获12个月随访。术后6个月36例疾病症状显著改善。术后12个月,膝关节功能主观评分表(IKDC) 2000分值、关节活动度均较术前明显提高(P 0. 01),MRI、关节镜检查显示关节软骨以及软骨下骨修复明显。结论对膝关节软骨损伤患者实施基质诱导自体软骨细胞移植,操作简便,安全且创伤轻。     

人异体骨软骨移植物保存方法研究

[目的]探讨六种保存方法对人关节软骨组织结构和细胞活性的影响,寻求一种保存效果较好的方法,为临床提供一种有活性的异体骨软骨移植物.[方法]自捐献新鲜尸体膝关节利用专用手术器械获取4.5 mm ×4.5 mm大小的人骨软骨块,分别采用梯度降温法、Co60射线照射+梯度降温法、玻璃化法、连续降温法、直接液氮法和酒精浸泡法对软骨块进行保存处理,分别于保存第8、15、30、60d时,采用蕃红-O组织染色、扫描电镜、软骨细胞胎盼蓝染色、MTT法等,观察并比较以上6种方法保存后关节软骨细胞存活率及其代谢功能变化.[结果]除了酒精保存方法外,其余保存方法随着时间延长软骨组织的细胞成活率和细胞代谢活性逐渐降低;保存60d时,采用玻璃化法保存软骨组织的细胞存活率为62.47％,软骨基质成分丢失较少,胶原纤维断裂不明显;采用慢速梯度降温法保存软骨组织的细胞存活率为59.75％,软骨基质成分丢失较多,胶原纤维断裂明显;其他保存方法软骨细胞存活率不足40％,软骨基质成分大量丢失,胶原纤维杂乱.[结论]六种保存方法中,玻璃化保存法能够较好的保存关节软骨,活性最好,其次是梯度降温保存法,两者均具有一定临床价值.Co60射线照射对软骨细胞有一定的损伤作用;酒精浸泡不能保存软骨细胞活性.     

膝关节外侧间室软骨退变对膝关节内侧单髁置换手术的影响

目的探讨膝关节合并外侧间室软骨轻度退变是否可行膝关节单髁置换术(UKA)及3.0T MRI在UKA病例选择的应用。方法笔者自2013-11—2015-08共诊治60例膝关节外侧间室软骨退变,根据术前X线片检查结果的Kellgren-Lawrence分级进行分组。A组:内侧间室软骨退变≥3级,前交叉韧带无明显损伤,外侧间室和髌股关节软骨退变0级,行UKA;B组:内侧软骨≥3级,外侧软骨1级。再通过膝关节3.0T MRI的Recht分级、美国医学会关节韧带损伤分度结果分组,B1组:内侧软骨≥Ⅲ级,外侧软骨损伤Ⅰ~Ⅱ级,关节韧带无明显损伤,行UKA;B2组:内侧软骨≥Ⅲ级,可合并外侧软骨损伤Ⅱ级、关节韧带≥Ⅰ°,行全膝关节置换术。结果共43例行UKA。UKA术后所有随访平均11.8(6~18)个月。A组(35例)、B1组(8例)末次随访KSS评分均较术前有所改善,差异有统计学意义(P0.05)。对2组间术后疼痛评分比较行方差齐性检验,方差不齐,差异无统计学意义(F=2.770,P=0.102);对2组术后功能评分比较行方差齐性检验,方差不齐,差异无统计学意义(F=1.102,P=0.299)。结论膝关节内侧间室软骨严重退变合并外侧间室软骨Ⅰ~Ⅱ级退变对UKA术后短期疗效未见明显影响。     

关节滑液3B3表位检测对软骨早期退变的诊断价值

[目的]骨性关节炎、髌骨软化症病人膝关节滑液中3B3表位含量是否与软骨退变程度相关。[方法]作者改良了竞争性ELISA检测关节滑液3B3表位的方法。抽吸71例膝骨关节炎、57例髌骨软化症病人及10例正常人志愿者的膝关节滑液，用该方法检测关节滑液中3B3表位含量，比较各组之间的差异。[结果]骨性关节炎组及髌骨软化组病人膝关节滑液中3B3表位均比正常人对照明显升高（P〈0．05），而且骨关节炎Ⅱ级关节软骨退变时关节滑液中3B3表位含量明显比Ⅳ级关节软骨退变增高（P〈0．01），而髌骨软骨软化患者Ⅱ、Ⅲ、Ⅳ级软骨退变各组间无明显差异（P〉0．05）。[结论]检测关节滑液中3B3表位含量具有诊断关节软骨退变的价值，尤其适用于骨性关节炎软骨早期退变（Ⅱ级）的诊断。     

Adjacent tissues (cartilage, bone) affect the functional integration of engineered calf cartilage in vitro

OBJECTIVE: An in vitro model was used to test the hypothesis that culture time and adjacent tissue structure and composition affected chondrogenesis and integrative repair in engineered cartilage. METHOD: Engineered constructs made of bovine calf chondrocytes and hyaluronan benzyl ester non-woven mesh were press-fitted into adjacent tissue rings made of articular cartilage (AC), devitalized bone (DB), or vital bone (VB) and cultured in rotating bioreactors for up to 8 weeks. Structure (light and electron microscopy), biomechanical properties (interfacial adhesive strength, construct compressive modulus), biochemical composition (construct glycosaminoglycans (GAG), collagen, and cells), and adjacent tissue diffusivity were assessed. RESULTS: Engineered constructs were comprised predominately of hyaline cartilage, and appeared either closely apposed to adjacent cartilage or functionally interdigitated with adjacent bone due to interfacial deposition of extracellular matrix. An increase in culture time significantly improved construct adhesive strength (P<0.001), modulus (P=0.02), GAG (P=0.04) and cellularity (P<0.001). The type of adjacent tissue significantly affected construct adhesion (P<0.001), modulus (P<0.001), GAG (P<0.001) and collagen (P<0.001). For constructs cultured in rings of cartilage, negative correlations were observed between ring GAG content (log transformed) and construct adhesion (R2=0.66, P<0.005), modulus (R2=0.49, P<0.05) and GAG (R2=0.44, P<0.05). Integrative repair was better for constructs cultured adjacent to bone than cartilage, in association with its solid architectural structure and high GAG content, and best for constructs cultured adjacent to DB, in association with its high diffusivity. CONCLUSIONS: Chondrogenesis and integrative repair in engineered cartilage improved with time and depended on adjacent tissue architecture, composition, and transport properties.     

Biochemical effects of two different hyaluronic acid products in a co-culture model of osteoarthritis

OBJECTIVES: To compare the effects of two hyaluronic acid (HA) formulations on mediators of matrix turnover and inflammation in an IL-1-treated cartilage-synovium co-culture model with the aim of elucidating mechanisms by which viscosupplementation exerts beneficial effects in osteoarthritic joints. DESIGN: A co-culture model (100 ng/ml interleukin-1beta (IL-1beta) added to canine synovial and cartilage explants) was used to investigate the effects of HA on cartilage-synovium interactions. Three concentrations (1x, 0.5x, and 0.1x) of two commercial sources of HA (A: Synvisc [hylan G-F 20]; B: Hyalgan [sodium hyaluronate]) were used. Co-cultures without IL-1beta (negative) or with IL-1beta (positive) but neither HA product served as controls. The liquid media were collected every 3 days and explants of cartilage and synovium were collected on days 3, 6, and 20. Media and explants were analyzed histologically, biochemically, and immunohistochemically. RESULTS: Glycosaminoglycan (GAG) content was measured in cartilage explants. GAG content in explants was higher in both HA groups at the beginning and the conclusion of the study compared to the IL-1beta-treated group. GAG content of the media was significantly (P<0.05) lower in the Synvisc group than all other groups early. The Hyalgan group demonstrated progressively less GAG release later in the study. The addition of Synvisc did not decrease the matrix metalloproteinase (MMP)-3 concentrations at any point. MMP-3 concentrations were significantly (P<0.05) lower among the 1x and 0.5x Hyalgan groups on day 20 compared to the IL-1beta-treated group. On day 3, prostaglandin E(2) concentrations were significantly (P<0.05) higher in the IL-1beta-treated group compared to other groups. Both HA groups had less nitric oxide production than the control groups throughout the study. CONCLUSIONS: This study supports two potential mechanisms for viscosupplementation: a biosynthetic-chondroprotective mechanism, with a possible delay in onset depending on the form of HA; and an anti-inflammatory mechanism.     

Development and remodeling of engineered cartilage-explant composites in vitro and in vivo

OBJECTIVE: Development and remodeling of engineered cartilage-explant composites were studied in vitro and in vivo. DESIGN: Individual and interactive effects of cell chondrogenic potential (primary or fifth passage bovine calf chondrocytes), scaffold degradation rate (hyaluronan benzyl ester or polyglycolic acid), and adjacent tissue cell activity and architecture (vital trabecular bone (VB), articular cartilage (AC), devitalized bone (DB) or digested cartilage (DC)) were evaluated over 8 weeks in vitro (bioreactor cultures) and in vivo (ectopic implants). RESULTS: In vitro, significant effects of cell type on construct adhesive strength (P<0.001) and scaffold type on adhesive strength (P<0.001), modulus (P=0.014), glycosaminoglycans (GAG) (P<0.001), and collagen (P=0.039) were observed. Chondrogenesis was best when the scaffold degradation rate matched the extracellular matrix deposition rate. In vivo, adjacent tissue type affected adhesive strength (P<0.001), modulus (P<0.001), and GAG (P<0.001) such that 8-week values obtained for bone (VB and DB) were higher than for cartilage (AC). In the AC/construct group, chondrogenesis appeared attenuated in the region of the construct close to the AC. In contrast, in the VB/construct group, a 500 microm thick zone of mature hyaline-like cartilage formed at the interface, and signs of active remodeling were present in the bone that included osteoclastic and osteoblastic activity and trabecular rebuttressing; these features were not present in the DB group or in vitro. CONCLUSIONS: Development and remodeling of composites based on engineered cartilage were mediated in vitro by cell chondrogenic potential and scaffold degradation rate, and in vivo by type of adjacent tissue and time.     

Relative contribution of matrix metalloprotease and cysteine protease activities to cytokine-stimulated articular cartilage degradation

OBJECTIVE: Both matrix metalloprotease (MMP) activity and cathepsin K (CK) activity have been implicated in cartilage turnover. We investigated the relative contribution of MMP activity and CK activity in cartilage degradation using ex vivo and in vivo models. METHODS: Bovine articular cartilage explants were stimulated with oncostatin M (OSM) 10 ng/ml and tumor necrosis factor-alpha (TNF-alpha) 20 ng/ml in the presence or absence of the broad-spectrum MMP inhibitor GM6001 and the cysteine protease inhibitor, E64. Cartilage degradation was evaluated in the conditioned medium by glycosaminoglycans (GAG), hydroxyproline, and cross-linked C-telopeptide fragments of type II collagen (CTX-II), which were compared to immunohistochemical evaluations of proteoglycans and CTX-II. We assessed MMP expression by gelatine zymography and CK expression by immunohistochemistry. In vivo, CTX-II release was measured from CK-deficient mice. RESULTS: OSM and TNF-alpha combined induced significant (P<0.01) increase in cartilage degradation products measured by hydroxyproline and CTX-II compared to vehicle control. The cytokines potently induced MMP expression, assessed by zymography, and CK expression investigated by immunohistochemistry. Inhibition of MMP activity completely abrogated hydroxyproline and CTX-II release (P<0.01) and GAG release (P<0.05). In contrast, E64 resulted in increased CTX-II release by 100% (P<0.05) and inhibited GAG release by 30%. Up-regulation of CTX-II fragments was confirmed in vivo in CK null mice. CONCLUSION: Inhibition of MMP activity reduced both proteoglycan loss and type II collagen degradation. In contrast, inhibition of cysteine proteases resulted in an increase rather than a decrease in MMP derived fragments of collagen type II degradation, CTX-II, suggesting altered collagen metabolism.     

Validation of an in vitro single-impact load model of the initiation of osteoarthritis-like changes in articular cartilage.

The objective of this study was the development and characterization of an in vitro model of the initiation of traumatic osteoarthritis (OA). Articular cartilage was obtained from seven healthy horses and from four horses diagnosed with OA. Cartilage disks were subjected to a single-impact load (500 g from 25, 50, or 100 mm) using a simple drop-tower device and cultured in vitro for up to 20 days. Cartilage sections were examined histologically to observe surface damage and proteoglycan loss. Percentage cell death was determined using TUNEL, release of glycosaminoglycans (GAG) to the medium was measured using the DMMB assay, and percentage weight gain calculated. Following a single-impact load and subsequent culture in vitro, articular cartilage explants demonstrated characteristic surface damage, proteoglycan loss, and chondrocyte death. This closely resembled degenerative changes observed in OA cartilage samples. A kinetic study showed that these degenerative changes (increased weight gain, GAG release into the medium, and chondrocyte death) were initiated within 48 h following impact and increased with recovery time in culture. These parameters were proportional to impact height, that is, impact energy. In conclusion, articular cartilage disks subjected to a single-impact load followed by 48 h of recovery time in culture in vitro developed traumatic OA-like changes. These changes can be quantified and compared, making the in vitro single-impact load model a useful tool for the elucidation of the early molecular pathways involved in the process leading from trauma to cartilage degeneration.     

软骨脱细胞基质支架材料的软骨组织工程实验研究

目的应用软骨脱细胞基质作为支架材料，按照组织工程的原理再生软骨，为修复软骨缺损探索新的途径。方法取新西兰大耳白兔1只，体重2．4kg，按改良Courtman法对兔耳软骨行脱细胞处理后用于实验。选用纯种6月龄新西兰大耳白兔18只，雌雄不限，体重2．4～2．6kg。每只耳形成2处1cm&#215;1cm软骨缺损，按修复方式不同随机分为3组，每组24处缺损。A组，软骨脱细胞基质加软骨膜；B组，软骨脱细胞基质；C组软骨膜，作为对照。术后每日观察兔耳修复区的大体变化，并分别于4、12周每组处死3只动物，于修复区切取标本，行HE染色、藏红花红一奥尔新蓝染色、II型胶原基因探针原位杂交实验。结果术后4周内A、B组大体形态无明显改变；术后12周可见修复区轻度增厚，触摸时质地较正常软骨稍硬。C组术后2周，2只2处修复区形成痂皮，术后5周痂皮脱落形成穿孔。术后4周，A、B组HE染色可见软骨脱细胞基质周边有轻度的炎性细胞浸润，以淋巴细胞为主，未形成包囊，藏红花红．奥尔新蓝染色均阴性；C组软骨缺损处的软骨膜塌陷，无细胞增殖现象；各组修复区均未见II型胶原基因探针原位杂交显色。术后12周，A组HE染色示部分软骨脱细胞基质内有新生细胞，细胞排列不规律，ECM嗜碱性增强，藏红花红-奥尔新蓝染色呈阳性，II型胶原基因原位杂交显色示新生细胞内均有大片棕黄色阳性染色区域；B组HE染色示软骨脱细胞基质无吸收现象，周边无包囊，炎性细胞消失，藏红花红一奥尔新蓝染色呈阴性，未见II型胶原基因原位杂交显色；C组HE染色示近软骨断端处可见部分形成新生组织，藏红花红一奥尔新蓝染色呈阳性，II型胶原基因原位杂交显色可见棕黄色阳性染色细胞。结论脱细胞软骨可诱导软骨膜细胞向其中生长而重建软骨，软骨膜和脱细胞软骨复合移植是软骨组织工程的另一种选择。     

外侧睑板条固定术联合射频技术矫正退行性下睑外翻

目的:研究外侧睑板条固定术联合射频技术在退行性下睑外翻矫正中的应用效果。方法:选取2018年1月-2019年4月的82例(90眼)退行性下睑外翻患者,随机分为两组。对照组采用Byron Smith改良术治疗,观察组采用外侧睑板条固定术联合射频技术治疗。观察两组治疗效果及术后恢复情况。结果:观察组总有效率显著高于对照组[93.02%(40/43)vs 71.79%(28/39)],差异有统计学意义(P<0.05)。两组治疗后均无明显不良反应。结论:外侧睑板条固定术联合射频技术矫正退行性下睑外翻效果显著,舒适安全,术后美观,可达到满意的临床效果。     

碱性成纤维细胞生长因子及相关细胞因子转染对兔骨关节炎的作用

目的 观察重组人碱性成纤维细胞生长因子(bFGF)单独及联合白细胞介素-1受体拮抗蛋白(IL-1Ra)和胰岛素样生长因子(IGF)-1基因转染对兔膝骨关节炎(OA)模型的治疗效果.方法 前交叉韧带切断法将新西兰兔膝关节制成OA模型.分别向膝关节内注射单独bFGF或多重组合的重组腺病毒载体各1×108 PFU.3周后关节液分析目的 基因表达和糖胺聚糖(GAG)浓度.关节标本行Mankin评分及Ⅱ型胶原免疫组织化学检测.结果 基因转染后,在关节液中可检测到相应目的基因的表达.OA组软骨损伤较大,Mankin评分为(8.60±1.14),关节液中GAG为(69.96±8.32)mg/L.与OA组相比,单独bFGF转染后软骨Mankin评分降低(P＜0.05),为(6.00±0.71);bFGF与IL-1Ra和IGF-1联合转染后,Mankin评分进一步降低(P＜0.05),为(3.80±0.84).单独bFGF转染后对GAG释放无明显抑制作用,联合基因转染可显著抑制基质降解,减少GAG的释放.结论 bFGF单独转染可对OA发挥一定的治疗作用.bFGF、IL-1Ra和IGF-1联合转染可有效改善OA病程,其疗效优于bFGF单独转染,提示多基因联合转染治疗OA更为有效.     

超声引导下射频消融联合乙醇消融与单纯射频消融治疗甲状腺良性囊实性结节的疗效对比

目的 探讨射频消融联合乙醇消融与单纯射频消融对良性囊实性甲状腺结节治疗效果的差异.方法 选取2015年1月-2018年7月就诊于郑州大学第一附属医院甲状腺外科,颈部彩超确认为甲状腺囊实性结节,且结节最大直径≥20 mm,穿刺病理结果为良性,拟行甲状腺射频消融手术的80例患者的病理资料,根据病情及患者意愿,分别行单纯射频...     

Endogenously produced adenosine regulates articular cartilage matrix homeostasis: enzymatic depletion of adenosine stimulates matrix degradation

OBJECTIVE: Enhanced extracellular levels of adenosine have been shown to inhibit experimentally induced cartilage degradation. The objective of this study was to investigate the role of adenosine and A(2)adenosine receptors in regulating cartilage homeostasis in the absence of inflammatory stimuli. METHODS: Cartilage explants were exposed to adenosine deaminase (ADA) to deplete extracellular adenosine, and conditioned medium was collected for evaluation of glycosaminoglycan (GAG), prostaglandin E(2)(PGE(2)), nitric oxide (NO), and matrix metalloproteinases-3 and -13 (MMP-3, MMP-13) levels. In a second set of experiments, cartilage incubated with ADA was simultaneously exposed to the adenosine kinase inhibitor 5'-iodotubercidin (ITU) to inhibit adenosine breakdown, or to the A(2A)adenosine receptor agonist N(6)-[2-(3,5-dimethoxyphenyl)-ethyl]adenosine (DPMA). Finally, explants were incubated with the adenosine receptor antagonists ZM241385, CGS15943, theophylline or caffeine to block normal receptor activation by endogenous adenosine. RESULTS: Exposure to ADA induced a concentration-dependent increase in GAG release and production of total MMP-3, MMP-13, PGE(2), and NO. Both ITU and DPMA inhibited the ADA-mediated increases in GAG release and PGE(2), and NO production, but only ITU inhibited MMP-13 release. Exposure to ZM 241385 increased GAG, MMP-3 and MMP-13 release. Additionally, CGS 15943 increased MMP-3 production while theophylline increased GAG, PGE(2), and NO release. CONCLUSIONS: Endogenous adenosine levels appear to regulate cartilage matrix homeostasis even in the absence of inflammation. Regulation occurs, at least in part, through activation of cell surface receptors. This study suggests that autocrine and paracrine responses to adenosine release are important for maintenance of healthy articular cartilage.