Articular Cartilage Restoration Research Articles

In vivo protection against interleukin-1-induced articular cartilage damage by transforming growth factor-beta 1: age-related differences.

Transforming growth factor-beta (TGF-beta) has been shown to antagonise interleukin-1 (IL-1) effects in different systems. Investigations were carried out to study whether TGF-beta 1 modulates IL-1 induced inflammation and IL-1 effects on articular cartilage in the murine knee joint. IL-1, TGF-beta 1 or both factors together were injected into the knee joint. Inflammation was studied in whole knee histological sections. Patellar cartilage proteoglycan synthesis was measured using 35S-sulphate incorporation while patellar cartilage glycosaminoglycan content was determined with automated image analysis on joint sections. Co-injection of TGF-beta 1 and IL-1 resulted in synergistic attraction of inflammatory cells. In contrast, TGF-beta 1 counteracted IL-1 induced suppression of articular cartilage proteoglycan synthesis. Proteoglycan depletion was similar shortly after the last injection of IL-1 or IL-1/TGF-beta 1, but accelerated recovery was found with the combination at later days. This protective effect of TGF-beta 1 could not be demonstrated in older mice. TGF-beta 1 aggravates IL-1 induced knee joint inflammation, but counteracts the deleterious effects of IL-1 on articular cartilage proteoglycan synthesis and content. The data indicate that TGF-beta 1 could play an important part in articular cartilage restoration after IL-1 induced proteoglycan depletion.

Articular cartilage thickness and glycosaminoglycan distribution in the young canine knee joint after remobilization of the immobilized limb

The recovery of articular cartilage from atrophy induced by joint immobilization was investigated in immature dogs. In a previous study, we showed that 11 weeks of immobilization of the knee (stifle) joint of young dogs reduced the concentration of articular cartilage glycosaminoglycans (GAGs) by 13-47%. In the present study, right hindlimbs from six female beagles were immobilized for 11 weeks, as in the previous study, and then were remobilized for 15 weeks. Cartilage from the knee joint was compared with cartilage from nonimmobilized knees of eight age-matched control beagles. Histological samples taken from 11 different locations of the knee joint were stained with safranin O, and microspectrophotometry was used to demonstrate distribution of GAGs in the tissue. After remobilization, GAG concentration was restored in the patellofemoral region and tibial condyles. On the summits of the femoral condyles, and especially at the periphery of the femoral condyles, GAG concentration remained 8-26% less than the control values. On the summits, the thickness of the uncalcified cartilage was as much as 15% less than in the age-matched controls. Consequently, the changes induced by unloading were reversible to a great extent, but a full restoration of articular cartilage was not obtained at all sites of the knee joint within the 15 weeks of remobilization. Immobilization of the skeletally immature joint therefore may affect the development of articular cartilage in such a way that very slow recovery or permanent alterations are induced.

Repair of rabbit articular surfaces with allograft chondrocytes embedded in collagen gel.

In an attempt to repair articular cartilage, allograft articular chondrocytes embedded in collagen gel, were transplanted into full-thickness defects in rabbit articular cartilage. Twenty-four weeks after the transplantation, the defects were filled with hyaline cartilage, specifically synthesising Type II collagen. These chondrocytes were autoradiographically proven to have originated from the transplanted grafts. Assessed histologically the success rate was about 80%, a marked improvement over the results reported in previous studies on chondrocyte transplantation without collagen gel. By contrast, the defects without chondrocyte transplantation healed with fibrocartilage. Immunological enhancement induced by transplanted allogenic chondrocytes or collagen was not significant at eight weeks after treatment, so far as shown by both direct and indirect blastformation reactions. Thus, allogenic transplantation of isolated chondrocytes embedded in collagen gel appears to be one of the most promising methods for the restoration of articular cartilage.