Effects of intraarticular hyaluronan on matrix changes induced in the lateral meniscus by total medial meniscectomy and exercise

Effects of a viscosupplementation therapy on rabbit menisci in an anterior cruciate ligament transection model of osteoarthritis

The aim of this study was to evaluate the morphological, microstructural, and mechanical effects of a viscosupplementation therapy on rabbit menisci at an early stage of osteoarthritis (OA). Anterior cruciate ligament transection (ACLT) was performed in twelve male New-Zealand White rabbits on the right knee joint. Six of these twelve rabbits received a mono intra-articular injection of high molecular weight hyaluronic acid (HA) two weeks after ACLT. Six additional healthy rabbits served as controls. Medial menisci were removed from all right knees (n=18) six weeks after ACLT and were graded macroscopically. Indentation-relaxation tests were performed in the anterior and posterior regions of the menisci. Collagen fiber organization and glycosaminoglycan (GAG) content were assessed by biphotonic confocal microscopy and histology, respectively. Viscosupplementation significantly (p=0.002) improved the surface integrity of the medial menisci compared to the operated non-treated group. Moreover, the injection seems to have an effect on the GAG distribution in the anterior region of the menisci. However, the viscoelastic properties of both operated groups were similar and significantly lower than those of the healthy group, which was explained by their modified collagen fiber organization. They displayed disruption of the tie fibers due to structural alterations of the superficial layers from which they emanate, leading to modifications in the deep zone. To conclude, the viscosupplementation therapy prevents macroscopic lesions of the menisci, but it fails to restore their collagen fiber organization and their viscoelastic properties. This finding supports the role of this treatment in improving the lubrication over the knee.

The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in sheep and goats

OBJECTIVE

Sheep and goats are commonly used large animal species for studying pathogenesis and treatment of osteoarthritis (OA). This review focuses on the macroscopic and microscopic criteria for assessing OA in sheep and goats and recommends particular assessment criteria to assist standardization in the conduct and reporting of preclinical trials of OA.

METHODS

A review was conducted of all published OA studies using sheep and goats and the most common macroscopic, microscopic, or ultrastructural scoring systems were summarised. General recommendations regarding methods of OA assessment in the sheep and goat have been made and a preliminary study of their reliability and utility was undertaken.

RESULTS

The modified Mankin scoring system is recommended for semiquantitative histological assessment of OA due to its already widespread adoption, ease of use, similarity to scoring systems used for OA in humans, and its achievable inter-rater reliability. Specific recommendations are also provided for histological scoring of synovitis and scoring of macroscopic lesions of OA.

CONCLUSIONS

The proposed system for assessment of sheep and goat articular tissues appears to provide a useful versatile method to quantify OA change. It is hoped that by adopting more standardised quantitative outcome measures, better comparison between different studies and arthritis models will be possible. The suggested scoring systems can be modified in the future as our knowledge of disease pathophysiology advances.

Dermatan sulfate in the synovial fluid of patients with knee osteoarthritis

Biochemical factors play an important role in osteoarthritis (OA) pathogenesis. The purpose of this study is to clarify whether the dermatan sulfate (DS) levels in the synovial fluid of patients with knee OA are related to residual cartilage. Synovial fluid was obtained from 51 OA patients. Knee radiographs were evaluated with the Kellgren-Lawrence (K/L) grading scale. The levels of the following disaccharides were measured by high-performance liquid chromatography (HPLC): DS (DSDeltaDi4S), chondroitin 6-sulfate (CSDeltaDi6S), and chondroitin 4-sulfate (CSDeltaDi4S). The concentration of cartilage oligomeric matrix protein (COMP) was measured by a sandwich ELISA. The levels of DSDeltaDi4S in Grades 0 and I OA were significantly higher than levels in Grade II (P = 0.0458), Grade III (P < 0.0001) and Grade IV (P < 0.0001), and we found strong relationships between the levels of DSDeltaDi4S and those of CSDeltaDi6S (P < 0.0001, r = 0.705), CSDeltaDi4S (P < 0.0001, r = 0.750), and COMP (P < 0.0001, r = 0.699). We conclude that the presence of DSDeltaDi4S reflects proteoglycan metabolism in the residual articular cartilage of OA patients. This suggests that metabolism of the small leucine-rich repeat proteoglycans decorin and biglycan, which contain chains of DSDeltaDi4S, is similar to that of aggrecan.

Effects of hyaluronan on the healing of rabbit meniscus injured in the peripheral region

The effect of hyaluronan (hyaluronic acid; HA) on the healing of rabbit meniscus injured in the peripheral region was assessed. A longitudinal tear was created in the peripheral region of the medial meniscus in 20 mature New Zealand white rabbits. One week after surgery, HA was injected into the left knee joint once a week for 5 weeks (HA group), while saline was injected into the right knee (control group). Six and 12 weeks after surgery, gross morphology, histology, and biochemical evaluations were performed. On gross morphological examination, there was evidence of meniscal healing in both groups, but the healing rate of the HA group was significantly higher than that of the control group at 12 weeks. Histologically, meniscal healing started at the tibial portion of the meniscal injury at 6 weeks in both groups, then advanced in the direction of the femoral surface at 12 weeks in the HA group. Biochemically, water and glycosaminoglycan contents did not differ significantly between the two groups. Hyaluronan maintained the healing process of the injured menisci, especially in the femoral surface, up to 12 weeks after injury.

The effects of hyaluronan on the meniscus and on the articular cartilage after partial meniscectomy

The effect of hyaluronan (molecular weight = 8 x 10(5)) on the meniscus and on the articular cartilage was assessed after partial meniscectomy in a rabbit model. On gross examination, remodeled meniscus appeared as newly synthesized translucent tissue, and was seen in both vehicle- and hyaluronan-treated menisci. Histologically, safranin O staining revealed the strong presence of glycosaminoglycans in the newly remodeled tissue, and polarized light demonstrated the absence of mature collagen architecture. Hydration of the hyaluronan-treated menisci was significantly less than that of the vehicle-treated menisci, and the reducible collagen cross-link dihydroxylysinonorleucine was significantly increased in the hyaluronan-treated menisci compared with the vehicle-treated menisci, indicative of a greater degree of collagen remodeling. In situ hybridization of vehicle- and hyaluronan-treated menisci revealed a high level of type I procollagen mRNA expression and minor expressions of types II and III mRNA. Expression of the type I collagen gene appeared to be more pronounced in the hyaluronan-treated menisci than in the vehicle-treated menisci. The tibial plateaus revealed mild cartilage fibrillation after partial meniscectomy. A statistically significant difference between vehicle- and hyaluronan-treated cartilage was not demonstrated in the present study because of the slow development (i.e., 12 weeks) of osteoarthritis after partial meniscectomy in the rabbit model. These results suggest that in the rabbit model, hyaluronan enhances collagen remodeling and inhibits meniscal swelling after partial meniscectomy in the avascular region.

Jump distance of dance landings influencing internal joint forces: II. Shear forces

Little is known about shear loading patterns during dance movements. The purpose of the study was to investigate the effect of jumping distance (JD) on contributors of ankle and knee shear forces (SF) generated during the landing phase of traveling jumps. Six female dancers performed 10 trials each at 30, 60, and 90% maximum jump distance (JD) and 15 jumps ranging from 35 to 100% JD. A sagittal view of the right leg landing onto a force platform was filmed using a high-speed cine camera. Greater ankle and knee joint reaction shear forces (JRSF) and quadriceps SF (QuadSF) were observed (P < 0.05) at increased JD. Although the triceps surae SF (TriSurSF) also increased at greater JD for all but one participant, the effect on minimizing the increase in the ankle SF was minor. The peak QuadSF magnitude and rate of loading were always greater than the corresponding knee JRSF variables. However, the increased QuadSF that occurred at longer jumps led to increased knee SF for only half of the participants.

Pathogenesis and treatment of osteoarthritis

OA represents the final common pathway of a number of pathologic processes. The challenge is to define and classify the subsets of OA to understand the causes and to devise specific therapies. Effective chondroprotective therapies will be most useful when applied to high-risk individuals before the emergence of symptomatic OA. This will be feasible only with an improved understanding of the complex interaction of genes and environment in the OA disease process. Moreover, identifying the heritable bases of this disease will provide insight into the molecular mechanisms of the complex pathway that results in OA. Clinicians who encounter and treat OA patients can look forward to the development of more effective and innovative therapies based on a rapidly improving understanding of OA.

Topographic variation in biglycan and decorin synthesis by articular cartilage in the early stages of osteoarthritis: an experimental study in sheep

Articular cartilage contains large molecular weight proteoglycans that aggregate with hyaluronic acid (aggrecan) and small species, particularly biglycan (dermatan sulphate proteoglycan-1) and decorin (dermatan sulphate proteoglycan-2), that do not. Mechanical stresses have been shown to profoundly influence the metabolism of aggrecan by articular chondrocytes; however, there are limited corresponding data on the metabolism of dermatan sulphate proteoglycans 1 and 2. The objective of this study was to examine the metabolism of aggrecan, biglycan, and decorin in articular cartilage from different weight-bearing areas of normal ovine stifle joints and in joints 6 months after menisectomy, a procedure that has been shown to induce early osteorthritic changes. [35S]proteoglycans synthesised by cartilage explants from eight different weight-bearing regions of unoperated and meniscectomised ovine stifle joints during 48 hours of culture were separated by size-exclusion chromatography, hydrophobic chromatography, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and were quantitated by phosphor-screen autoradiography. The synthesis and degradation of the proteoglycans were expressed relative to the DNA content of the explants. In control joints, the cartilage exposed to high contact stress synthesised significantly less proteoglycan overall and more decorin than joint regions bearing less stress. Explants from high stress regions also released significantly greater amounts of resident proteoglycans (dimethylmethylene blue positive) into media during culture. After lateral meniscectomy, the lateral tibial and femoral cartilages showed elevated biosynthesis of both 35S-dermatan sulphate proteoglycans 1 and 2. This chondrocyte biosynthetic response was accompanied by increased catabolism of aggrecan and the release of its degradation products into culture media. These experiments revealed, in normal joints, a topographic variation in proteoglycan synthesis by articular cartilage that was related to the mechanical stress to which the tissues were subjected in vivo. This biosynthetic pattern changed when the load distribution of the joint was altered by unilateral meniscectomy. These data suggest that an altered chondrocyte phenotypic expression of proteoglycans in response to abnormal mechanical loading is an early event in osteoarthritis.

Effects of transforming growth factor beta on proteoglycan synthesis by cell and explant cultures derived from the knee joint meniscus

Repair of meniscal tears depends in part upon the ability of the resident fibrochondrocytes to produce new extracellular matrix molecules including proteoglycans. Three culture systems have been used to investigate proteoglycan production by meniscal fibrochondrocytes from the inner, middle and outer zones of medial and lateral menisci of the sheep stifle joint. Cultures of meniscal explants, monolayered cells, and cells encapsulated in alginate beads were labeled with 35SO4H2 for 48 h in the absence and presence of transforming growth factor beta (TGF beta) and the proteoglycans were analysed by Sephacryl S-1000 chromatography. In general, the lateral meniscus produced more proteoglycan than the medial. Explants from the inner and middle zones produced predominantly aggrecan-like proteoglycan, together with a smaller proteoglycan population eluting with an average distribution coefficient of around 0.65. The outer meniscal zones synthesized less proteoglycan overall, the majority of which consisted of the smaller proteoglycans. These characteristic proteoglycan size profiles obtained with explant cultures also were preserved when cells isolated from the respective zones were cultured in alginate beads. Monolayer cell cultures, however, produced almost entirely small proteoglycans, regardless of their zone of origin. Chromatography of chondroitinase AC and ABC digested samples indicated that the small proteoglycan population comprised mostly dermatan sulphate-containing proteoglycans. In all meniscal zones and in all culture systems, TGF beta stimulated proteoglycan production by up to 100% and the proteoglycans were slightly larger. TGF beta also stimulated cell division in fibrochondrocyte monolayer cultures. Long term intermittent stimulation of alginate bead cultures with TGF beta resulted in large increases in proteoglycan synthesis, increased aggregation of large proteoglycan monomers, and an increase in the production of the larger of two small proteoglycans, putatively, biglycan.

The effects of orally administered calcium pentosan polysulfate on inflammation and cartilage degradation produced in rabbit joints by intraarticular injection of a hyaluronate-polylysine complex

OBJECTIVE

To determine the antiinflammatory and cartilage-protecting activities of orally administered calcium pentosan polysulfate (CaPPS) in a rabbit model of inflammatory arthritis.

METHODS

A single intraarticular injection of a preformed polycation complex (PC) of poly-D-lysine and hyaluronan was used to induce joint inflammation; saline was injected into the contralateral joint as a control. Animals were killed 1, 4, 7, or 10 days post-PC injection. CaPPS, at 5 mg/kg, 10 mg/kg, or 75 mg/kg, was given every 48 hours commencing 7 days prior to PC injection. Serum interleukin-6 (IL-6), synovial fluid (SF) prostaglandin E2, cell numbers, and cartilage proteoglycan (PG) content, composition, and biosynthesis were determined for PC- and saline-injected joints.

RESULTS

In PC-injected, non-drug-treated animals, serum IL-6 activity, SF leukocyte numbers, and prostaglandin E2 levels were elevated, while cartilage PG content and biosynthesis were reduced. CaPPS at 10 mg/kg, but not at 5 mg/kg, decreased serum IL-6 levels but maintained cartilage PG concentration and biosynthesis. However, SF leukocyte counts and prostaglandin E2 levels (except on day 1) were not reduced.

CONCLUSION

The ability of CaPPS to attenuate serum IL-6 levels and preserve cartilage PGs in inflamed rabbit joints suggests that this substance could be of value as an effective orally administered chondroprotective, antiarthritic drug.