Expression of MMP-1 in cartilage and synovium of experimentally induced rabbit ACLT traumatic osteoarthritis: immunohistochemical study

To observe the level and the distribution of MMP-1 in cartilage and synovium over the progression of OA in rabbit ACLT model, and to explore the relationship between the amount of MMP-1 expression and the degree of OA cartilage degradation. OA was induced in 20 rabbits by anterior cruciate ligament transection (ACLT) and ten rabbits were killed at 4 and 8 weeks after the operation, respectively. A further ten rabbits received unilateral knee arthrotomy as controls. Cartilage degradation was observed under dissecting microscope, immunohistochemical, and morphometric analysis were adopted to record the tissue level and distribution of MMP-1 in cartilage and synovium. Cartilage degradation in both ACLT groups was more severe than that in control group, and the degradation in 8-week ACLT group was more severe than that in 4-week ACLT group. MMP-1 was expressed predominantly in the superficial and upper intermediate layers of cartilage and in the lining layer of synovium. Its expression was increased steadily over the progression of OA both in cartilage and in synovium, but there was a little difference in the increase pattern between them: increase of MMP-1 in synovium lagged behind that in cartilage in early stage of OA. Conclusion: MMP-1 was involved in OA development in rabbit ACLT model and the amount of its expression was related with the degree of cartilage degradation. The increase of MMP-1 expression in synovium lagged behind that in cartilage, suggesting OA pathology was originated from cartilage, but synovitis may also paticipate in cartilage degradation, especially in middle and late stage of OA. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

壳聚糖膝关节腔内注射疗法对兔骨关节炎关节软骨的影响

目的观察关节内注射羧甲基壳聚糖(CMCTS)对兔骨关节炎(OA)关节软骨退变及软骨基质金属蛋白酶(MMP)-1,-3mRNA表达的影响。方法24只大耳白兔行单侧膝关节前交叉韧带切断术,术后5周将动物随机分为3组,A组关节内注射2%CMCTS0.3ml,每2周1次;B组关节内注射1%透明质酸钠(HA)0.3ml,每周1次;C组关节内不注射药物。术后11周处死动物,观察各组股骨内髁关节软骨的大体变化,采用反转录-聚合酶链反应(RT-PCR)方法检测股骨内髁退变软骨中MMP-1和MMP-3的mRNA表达。结果CMCTS和HA注射组软骨退变程度较不用药组明显减轻,CMCTS注射组软骨MMP-1、MMP-3的mRNA表达明显低于HA注射组和不用药组。HA注射组软骨MMP-1和MMP-3的mRNA表达与不用药组比较,差异没有显著性意义。结论CMCTS能够明显抑制OA软骨MMP-1和MMP-3的mRNA表达,明显减轻软骨退变的程度,CMCTS对早期OA软骨有修复保护作用。     

高脱乙酰度羧甲基壳聚糖对兔膝骨关节炎软骨诱导型一氧化氮合酶表达的影响

目的观察高脱乙酰度羧甲基壳聚糖(HD-CMC)经关节腔注射后对兔膝骨关节炎(OA)软骨诱导型一氧化氮合酶(iNOS)的mRNA和蛋白表达的影响,探讨其用于OA防治的机制及可能性。方法36只日本大耳白兔,行右侧膝关节前交叉韧带切断术(ACLT),术后随机分为2组,实验组于术后当天开始关节腔内注射2%HD-CMC 0．15mg/kg,每2周给药1次,对照组同一时间点关节腔内注射0．9%生理盐水0．15mg/kg。实验组与对照组于第6周分别随机处死大白兔各9只,剩余大白兔于第12周处死,对比两组大白兔股骨髁关节软骨的大体改变,用反转录聚合酶链反应(RT-PCR)及免疫组织化学的方法检测iNOS在软骨中的mRNA和蛋白的表达。结果实验组退变软骨的大体评分轻于对照组,NOS的mRNA和蛋白表达水平均低于对照组。结论HD-CMC能够降低OA退变软骨iNOS的表达,并延缓软骨的退行性变,对OA退变软骨具有修复保护作用。     

透明质酸钠对兔骨关节炎软骨诱导型NO合酶基因表达的影响

目的观察透明质酸钠(Na—HA)关节腔注射对骨关节炎(OA)模型关节软骨中诱导型NO合酶(iNOS) mRNA表达水平的影响。方法16只大耳白兔行单侧前交叉韧带切断术，术后5周将动物随机分为实验组和对照组，实验组关节腔注射1％Na—HA 0.3ml，每周1次，连续5周，对照组则注射等量生理盐水。术后10周处死动物，观察两组股骨内髁关节软骨的大体形态学和组织学病理改变，采用反转录一聚合酶链反应(RT—PCR)方法检测软骨iNOS mRNA的表达。结果实验组软骨退变程度较对照组明显减轻，实验组软骨中iNOS mRNA的表达水平与对照组比较差异无统计学意义。结论Na—HA能有效地减轻早期OA关节软骨的退变程度，Na—HA对早期OA软骨中的iNOS的表达没有下调作用。     

Chondroprotective activity of N-acetylglucosamine in rabbits with experimental osteoarthritis

OBJECTIVE: To examine the therapeutic efficacy of N-acetylglucosamine (GlcNAc) in rabbits with experimental osteoarthritis (OA). METHODS: Experimental OA was induced in rabbits by anterior cruciate ligament transection (ACLT). In the first study, rabbits (six in each group) received intramuscular injections of GlcNAc or normal saline three times a week starting 1 week postoperatively. In the second study, rabbits (eight in each group) were injected intra-articularly with GlcNAc (either once or twice a week) or normal saline. In the third study, rabbits (seven in each group) were injected intra-articularly twice a week with either GlcNAc, hyaluronan, or normal saline. Animals were killed 8 weeks after ACLT for macroscopic and histological assessment of the knee joints. RESULTS: Intramuscular administration of GlcNAc in rabbits with experimental knee OA did not show chondroprotective effects but showed mild anti-inflammatory activity. In contrast, intra-articular administration of GlcNAc twice a week reduced cartilage degradation. Additionally, intra-articular GlcNAc also suppressed synovitis. Once a week intra-articular injections of GlcNAc did not demonstrate therapeutic efficacy. The chondroprotective efficacy of GlcNAc was better than that of viscosupplementation treatment with hyaluronan. CONCLUSION: Intra-articular GlcNAc has chondroprotective and anti-inflammatory activity in experimental OA.     

透明质酸钠关节腔内注射对兔软骨的保护作用及对过氧化物酶体增殖物激活受体γ mRNA表达的影响

目的 观察关节腔内注射透明质酸钠(Na-HA)对骨关节炎(OA)软骨的保护作用及对过氧化物酶体增殖物激活受体γ(PPAR-γ)mRNA表达的影响,探讨Na-HA治疗OA的机制.方法 48只大耳白兔随机分为A、B、C 3组,每组16只,A组为正常对照组,B、C两组行单膝前交叉韧带切断术,术后第5周开始,B组关节腔内注射0.3 ml生理盐水;C组注射等量的高分子量1%Na-HA,每周1次,连续5周.术后11周处死动物,比较各组股骨内髁关节软骨的大体变化,苏木素-伊红(HE)染色观察股骨内髁软骨的病理变化,番红O染色观察软骨基质的改变,采用实时定量聚合酶链反应(Real-Time PCR)方法检测软骨PPAR-γ mRNA的表达水平.结果 大体评分显示B组软骨退变的程度明显重于A组和C组(P＜0.05);HE染色与A、C两组比较,B组软骨明显溃疡形成;番红O染色平均灰度值B组软骨基质染色明显高于A、c两组(P＜0.05);B组软骨PPAR-γ mRNA表达量明显高于A、C两组(P＜0.05);A、C两组大体评分和PPAR-γ mRNA表达量差异无统计学意义.结论 关节腔注射Na-HA可以抑制软骨PPAR-γmRNA表达,减轻软骨退变的程度,可能是其治疗骨关节炎的机制之一.     

Astaxanthin ameliorates cartilage damage in experimental osteoarthritis

Abstract

Purpose. Astaxanthin is a red-pigment carotenoid found in certain marine animals and plants. Astaxanthin has been shown to inhibit matrix metalloproteinases (MMPs) expression in vitro. However, the effect of astaxanthin on cartilage is still unclear. The aim of this study was to investigate the effects of astaxanthin on cartilage in experimental osteoarthritis (OA).

Methods. New Zealand rabbits underwent anterior cruciate ligament transection to induce OA in right knee. Rabbits received intra-articular injection containing 0.3 ml of vehicle (dimethyl sulfoxide) or astaxanthin (50 μM). Injection was started on the day of operation, and the injection were performed once weekly for six consecutive weeks. Then, rabbits were sacrificed and the right knees were harvested for study.

Results. Cartilage degradation was reduced by astaxanthin, as assessed by morphological and histological examination. Astaxanthin inhibited the gene expression of MMP-1, MMP-3, and MMP-13 in cartilage as compared with the vehicle group.

Conclusions. The results suggest that astaxanthin may be considered as pharmaceutical agent in OA treatment.     

羧甲基壳聚糖对兔骨关节炎软骨一氧化氮合酶表达的影响

目的探讨关节腔注射羧甲基壳聚糖(CMCTS)对骨关节炎(OA)软骨诱导型一氧化氮合酶(iNOS)表达的影响。方法大耳白兔32只,每只兔单侧膝关节行前交叉韧带切断术,术后5周将兔随机分为4组,每组8只,A组：关节腔注射2%高相对分子质量的CMCTS 0．3ml,每2周重复1次；B组：同等条件下注射2%低相对分子质量的CMCTS 0．3ml；C组：关节腔注射1%透明质酸钠(Na-HA)0．3ml,每周重复1次；D组：关节腔不注射任何药物。术后11周处死动物。采用免疫组织化学、反转录聚合酶链反应(RT-PCR)方法检测软骨iNOS的表达。结果免疫组织化学及RT-PCR显示CMCTS注射组软骨iNOS的表达水平显著低于Na-HA注射组和不用药组,不同相对分子质量CMCTS注射组之间、Na-HA注射组和不用药组之间比较,iNOS的表达差异无统计学意义。结论CMCTS能够明显抑制OA软骨i NOS的表达,Na-HA对OA软骨iNOS的表达没有显著下调作用。     

Effect of hyaluronan on chondrocyte apoptosis and nitric oxide production in experimentally induced osteoarthritis

OBJECTIVE: Nitric oxide (NO) plays an important role in cartilage degeneration, and NO donors induce chondrocyte apoptosis. This study evaluated the effect of intraarticular injections of hyaluronan (HA) on chondrocyte apoptosis and NO production using an experimental osteoarthritis (OA) model. METHODS: Thirty-six New Zealand white rabbits underwent unilateral anterior cruciate ligament transection (ACLT), and were divided into 3 groups. Four weeks after ACLT, the HA group started intraarticular HA injections once a week for 5 weeks; the vehicle group started to receive the carrier of HA; the no injection group received no treatment. All ACLT knees were harvested at Week 9 and evaluated for OA severity. Culture supernatants of the cartilage were analyzed for nitrite concentration. Cartilage sections were analyzed by TUNEL for apoptosis and by immunohistochemistry for nitrotyrosine. RESULTS: OA in the HA group was less severe than the other 2 groups. The number of apoptotic chondrocytes was significantly lower in the HA group. HA injection did not influence NO production in cartilage. CONCLUSION: HA protects against chondrocyte apoptosis during the development of OA, while it may not have definite effects on NO production in the joints. These inhibitory effects of HA on chondrocyte apoptosis may play a role in its mechanism of action in chondroprotection.     

Caspase inhibitors reduce severity of cartilage lesions in experimental osteoarthritis

OBJECTIVE: To examine the therapeutic efficacy of caspase inhibitors in experimental osteoarthritis (OA). METHODS: Experimental OA was induced in rabbits by anterior cruciate ligament transection (ACLT). Rabbits were treated with intraarticular (i.a.) injections of caspase inhibitors 3 times per week starting 1 week postoperatively. Animals were killed 9 weeks after ACLT, for macroscopic, histologic, and immunohistochemical assessment of the knee joints. RESULTS: I.a. administration of the pan-caspase inhibitor Z-VAD-FMK significantly reduced cartilage degradation, as assessed by macroscopic and microscopic criteria. Untreated knees showed large numbers of chondrocytes with active caspase 3 and the p85 fragment of poly(ADP-ribose) polymerase (PARP p85) that is generated during apoptosis. The frequency of cells positive for PARP p85 and active caspase 3 was reduced in Z-VAD-FMK-treated knees. Inhibitors specific for caspase 3 or caspase 8 showed no significant efficacy. Caspase 1 inhibitor and the combination of caspase 3 and caspase 8 inhibitors reduced OA pathology. CONCLUSION: These results provide direct support for a role of cell death in OA pathogenesis. Caspase inhibitors reduced the severity of cartilage lesions in experimental OA, suggesting that they may have disease-modifying activity in human OA.     

Trichostatin A inhibits expression of cathepsins in experimental osteoarthritis

The aim of this study was to investigate the effects of trichostatin A (TSA) on expression of cathepsins in cartilage in experimental osteoarthritis (OA). OA was induced in 18 rabbits by bilateral anterior cruciate ligament transection (ACLT). Four weeks after surgery, rabbits received intra-articular injection with TSA dissolved in the dimethylsulphoxide (DMSO) in the right knees and DMSO in the left knees once a week for 5 weeks. Rabbits were killed 7 days after the last injection. The knee joints were assessed by morphological and histological examination. Messenger RNA expression of cathepsins K, B, L, S and cystatin C was studied by real-time PCR. TSA inhibited the expression of cathepsins K, B, L, S and cystatin C accompanied with the less degradation in cartilage. The results suggest that TSA exhibits protective effects against cartilage degradation in rabbits with OA and the effects may be associated with the inhibition of cathepsins.     

The effects of glucosamine hydrochloride on subchondral bone changes in an animal model of osteoarthritis

OBJECTIVE: To quantify periarticular subchondral bone changes in a rabbit model of experimental osteoarthritis (OA), and to determine the effects of continuous administration of a clinically relevant dose of glucosamine HCl on subchondral bone changes in this model. METHODS: Anterior cruciate ligament transection (ACLT) was performed on the left femorotibial joints of 16 rabbits to induce OA. Ten rabbits that did not undergo ACLT served as unoperated controls. Eight rabbits that underwent ACLT and 6 control rabbits were treated with 100 mg of glucosamine daily, and the others were given a placebo. The articular cartilage was evaluated macroscopically and graded at the time of necropsy, 8 weeks after ACLT. Bone mineral density (BMD) was measured using dual-energy x-ray absorptiometry on the dissected distal femur and proximal tibia. Subchondral trabecular bone turnover, architecture, and connectivity, as well as subchondral plate thickness and mineralization were studied on the undecalcified tibia sections from each animal. RESULTS: Eight weeks after ACLT, most of the operated joints had various degrees of cartilage damage and fibrillation. Compared with the control group, the ACLT group had significantly increased subchondral bone turnover and lower BMD, bone volume, connectivity, and bone mineralization. The high bone turnover was significantly reduced in glucosamine-treated animals that underwent ACLT. In fact, there were no significant differences between the ACLT/glucosamine group and the control/glucosamine group in most of the bone parameters studied. CONCLUSION: This study shows that subchondral bone turnover, structure, and mineralization are significantly altered in the early stages of experimental OA, and that these changes are attenuated by glucosamine treatment.     

The role of subchondral bone remodeling in osteoarthritis: reduction of cartilage degeneration and prevention of osteophyte formation by alendronate in the rat anterior cruciate ligament transection model

OBJECTIVE: It has been suggested that subchondral bone remodeling plays a role in the progression of osteoarthritis (OA). To test this hypothesis, we characterized the changes in the rat anterior cruciate ligament transection (ACLT) model of OA and evaluated the effects of alendronate (ALN), a potent inhibitor of bone resorption, on cartilage degradation and on osteophyte formation. METHODS: Male Sprague-Dawley rats underwent ACLT or sham operation of the right knee. Animals were then treated with ALN (0.03 and 0.24 microg/kg/week subcutaneously) and necropsied at 2 or 10 weeks postsurgery. OA changes were evaluated. Subchondral bone volume and osteophyte area were measured by histomorphometric analysis. Coimmunostaining for transforming growth factor beta (TGF beta), matrix metalloproteinase 9 (MMP-9), and MMP-13 was performed to investigate the effect of ALN on local activation of TGF beta. RESULTS: ALN was chondroprotective at both dosages, as determined by histologic criteria and collagen degradation markers. ALN suppressed subchondral bone resorption, which was markedly increased 2 weeks postsurgery, and prevented the subsequent increase in bone formation 10 weeks postsurgery, in the untreated tibial plateau of ACLT joints. Furthermore, ALN reduced the incidence and area of osteophytes in a dose-dependent manner. ALN also inhibited vascular invasion into the calcified cartilage in rats with OA and blocked osteoclast recruitment to subchondral bone and osteophytes. ALN treatment reduced the local release of active TGF beta, possibly via inhibition of MMP-13 expression in articular cartilage and MMP-9 expression in subchondral bone. CONCLUSION: Subchondral bone remodeling plays an important role in the pathogenesis of OA. ALN or other inhibitors of bone resorption could potentially be used as disease-modifying agents in the treatment of OA.     

In vivo selective inhibition of mitogen-activated protein kinase kinase 1/2 in rabbit experimental osteoarthritis is associated with a reduction in the development of structural changes

OBJECTIVE: The primary aim of this study was to investigate, using an experimental rabbit model of osteoarthritis (OA), the effect of a selective mitogen-activated protein kinase kinase 1/2 (MEK-1/2) inhibitor, PD 198306, on the development of structural changes. Additional aims were to assess the effects of the inhibitor on levels of phosphorylated extracellular signal-regulated kinase 1/2 (phospho-ERK-1/2) and matrix metalloproteinase 1 (MMP-1; collagenase 1) in OA chondrocytes. METHODS: After surgical sectioning of the anterior cruciate ligament of the right knee joint, rabbits with OA were separated into 3 experimental groups: oral treatment with placebo or with PD 198306 at a therapeutic concentration of 10 mg/kg/day or 30 mg/kg/day. Each treatment started immediately after surgery. The animals were killed 8 weeks after surgery. Macroscopic and histologic studies were performed on the cartilage and synovial membrane. The levels of phospho-ERK-1/2 and MMP-1 in OA cartilage chondrocytes were evaluated by immunohistochemistry. Normal, untreated rabbits were used as controls. RESULTS: OA rabbits treated with the highest dosage of MEK-1/2 inhibitor showed decreases in the surface area (size) of cartilage macroscopic lesions (P < 0.002) and in osteophyte width on the lateral condyles (P = 0.05). Histologically, the severity of synovial inflammation (villous hyperplasia) was also reduced (P < 0.02). In cartilage from placebo-treated OA rabbits, a significantly higher percentage of chondrocytes in the superficial layer stained positive for phospho-ERK-1/2 and MMP-1 compared with normal controls. Rabbits treated with the highest dosage of PD 198306 demonstrated a significant and dose-dependent reduction in the level of phospho-ERK-1/2 and a lower level of MMP-1. CONCLUSION: This study demonstrates that, in vivo, PD 198306, a selective inhibitor of MEK-1/2, can partially decrease the development of some of the structural changes in experimental OA. This effect was associated with a reduction in the level of phospho-ERK-1/2 in OA chondrocytes, which probably explains the action of the drug.     

Effect of dehydroepiandrosterone on cartilage and synovium of knee joints with osteoarthritis in rabbits

The aim of this study was to investigate the effects of intra-articular injection of dehydroepiandrosterone (DHEA) on cartilage and synovium of knee joints with osteoarthritis (OA) in rabbits and the underlying mechanism. Forty rabbits underwent unilateral anterior cruciate ligament transaction and were divided into two groups. Rabbits were injected with 100 μmol/l DHEA dissolved in the dimethylsulphoxide (DMSO) in the knee joints 5 weeks after transaction, once a week for 5 weeks. Rabbits injected with DMSO under the same condition were served as a control. All rabbits were killed 1 week after the last injection. The knee joints were evaluated by gross morphology, histology, and gene expression analysis. Gross morphologic inspection and histological evaluation showed that the DHEA group appeared less damage in cartilage and synovium as compared with the control. Gene expression analysis revealed that the mRNA expression of matrix metalloproteinase-3 (MMP-3) in cartilage and synovium decreased significantly in the DHEA group and that of tissue inhibitor of metalloproteinase-1 (TIMP-1) increased. No significant difference of interleukin-1 beta (IL-1β) mRNA expression was found in the cartilage between two groups while the mRNA expression of IL-1β in the synovium was largely suppressed in the DHEA group. The study suggests that DHEA plays a protective role against cartilage degradation and synovium inflammation in rabbits with OA. This role may be achieved through the regulation of the MMP-3, TIMP-1, and IL-1β gene expression in the cartilage and synovium.     

Effect of oral glucosamine on cartilage degradation in a rabbit model of osteoarthritis

OBJECTIVE: To determine whether oral glucosamine alleviates cartilage degradation in an animal model of osteoarthritis (OA). METHODS: The effect of 8 weeks of daily oral glucosamine hydrochloride on degeneration of articular cartilage was evaluated in rabbits in which anterior cruciate ligament transection (ACLT) was performed to induce OA. Animals were treated with glucosamine (n = 16) or a placebo (n = 16) and necropsied at 11 weeks. Seven unoperated rabbits served as controls. The articular cartilage was evaluated macroscopically and histologically and analyzed for total type II collagen and glycosaminoglycan (GAG) content. RESULTS: Histologic analysis revealed that loss of proteoglycan, based on Safranin O-fast green staining, was significantly reduced in the lateral tibial plateau cartilage of ACL-transected limbs in the glucosamine group compared with ACL-transected limbs in the placebo group, with a similar, but not significant, trend for the lateral femoral condylar cartilage. Likewise, macroscopic analysis of cartilage showed that the lateral tibial plateau alone had a significantly lower rate of disease in the glucosamine group, which was consistent with the results of the independent histologic assessment. However, no significant treatment effect was detected when composite histologic scores were analyzed. A significant reduction in GAG content was observed in the femoral condyles of placebo-treated ACL-transected joints, but not in the same region of glucosamine-treated ACL-transected joints, compared with their respective contralateral unoperated joints. CONCLUSION: Oral administration of glucosamine had a detectable, site-specific, partial disease-modifying effect in this model of OA. From a clinical perspective, the administration of glucosamine did not prevent fibrillation and/or erosions of the articular cartilage in all of the treated animals, and no effects were detected in the medial joint compartments.     

Role of apoptotic and matrix-degrading genes in articular cartilage and meniscus of mature and aged rabbits during development of osteoarthritis

OBJECTIVE: To determine expression patterns of apoptotic and matrix-degrading genes during aging and development of osteoarthritis (OA), using a rabbit model of induced OA. METHODS: Six mature and 6 aged rabbits underwent anterior cruciate ligament transection and were killed 4 and 8 weeks after surgery, respectively, to create early-grade and advanced-grade OA. RNA from articular cartilage and menisci was examined for expression of the genes caspase 8, Fas, Fas ligand, p53, aggrecanase, matrix metalloproteinase 1 (MMP-1), and MMP-3. A second cohort of animals that had undergone no intervention in the joint was also killed. Parametric data were analyzed with analysis of variance and Student's t-tests, while nonparametric data were assessed with the Mann-Whitney U test. RESULTS: Expression levels of Fas, caspase 8, FasL, and MMP-1 were significantly higher (>100%) in aged cartilage compared with mature cartilage (P < 0.05). After induction of OA, expression of apoptotic genes in aged rabbits remained high, while significant up-regulation of Fas and caspase 8 (nearly 150% increase) was observed in mature rabbits (P < 0.05). No significant up-regulation of these genes was observed in the menisci of aged or mature rabbits prior to or after induction of OA. Development of OA occurred more rapidly in aged cartilage compared with mature cartilage (P < 0.05). CONCLUSION: Differential expression of apoptotic and matrix-degrading genes occurs in aged compared with mature cartilage, both at baseline and during development of OA. This may be responsible for faster degradation of aged cartilage and its predisposition for developing OA.     

Effects of dehydroepiandrosterone on articular cartilage during the development of osteoarthritis

OBJECTIVE: To investigate the in vivo effects of dehydroepiandrosterone (DHEA) on knee joints during the development of experimentally induced osteoarthritis (OA). METHODS: Twenty-two mature NZW rabbits underwent bilateral anterior cruciate ligament transection (ACLT) and received 0.3-ml intraarticular injections of DHEA (at a concentration of 100 microM in phosphate buffered saline) and control solution in the right and left knees, respectively, beginning 4 weeks after ACLT and continuing once weekly for 5 weeks. All animals were killed 9 weeks after surgery, and the knee joints were assessed by gross morphologic, histologic, histomorphometric, and biochemical methods. RESULTS: Gross morphologic inspection following India ink application showed that the right femoral condyles, which received DHEA, demonstrated less severe cartilage damage than did the contralateral condyles. The thickness, area, and roughness of the DHEA-treated femoral condyles provided evidence of a cartilage-protecting effect of DHEA following ACLT. These results were supported by gene expression analysis. Messenger RNA expression of a proinflammatory cytokine, interleukin-1beta, and catabolic enzymes, matrix metalloproteinases 1 and 3, was reduced in the cartilage of the DHEA-treated knee joints, and expression of tissue inhibitor of metalloproteinase 1 was increased. CONCLUSION: Results of the present study demonstrate a cartilage-protecting effect of DHEA during the development of OA following ACLT in a rabbit model.