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Cartilage-derived retinoic acid-sensitive protein (CD-RAP) is a new protein that was isolated from bovine articular chondrocytes and human melanoma cell lines (melanoma inhibitory protein or MIA). In normal tissue its expression is limited to cartilage, and in morbid tissue to melanoma, chondrosarcoma, and breast cancer. Serum levels of CD-RAP/MIA correlate with the progression of malignant melanoma, but there have been no reports on chondrosarcoma. Here, it was first demonstrated by RT-PCR and immuno-histological methods that CD-RAP was expressed in tissue from a Swarm rat chondrosarcoma that was used as an experimental model. The course following tumor transplantation and changes in serum CD-RAP after tumor excision were then observed to investigate whether serum CD-RAP could be used as a marker of tumor activity. Consequently, serum CD-RAP in control rats tended to decrease as the animal grew, whereas it rose in proportion to tumor proliferation in rats that had received a tumor graft. Serum CD-RAP levels dropped rapidly following excision of the tumor in a group of tumor-excised rats. In those rats which had a recurrence following excision of the tumor, serum CD-RAP rose prior to the appearance of the tumor. Serum CD-RAP thus sensitively reflected tumor onset and proliferation, so that it appeared to be an effective marker of tumor activity for Swarm rat chondrosarcoma. [Copyright &y& Elsevier]

Abstract: This study has assessed the relative proportions of type I and II collagens and IIA procollagen in full depth biopsies of repair tissue in a large sample of patients treated with autologous chondrocyte implantation (ACI). Sixty five full depth biopsies were obtained from knees of 58 patients 8–60 months after treatment by ACI alone (n =55) or in combination with mosaicplasty (n =10). In addition articular cartilage was examined from eight individuals (aged 10–50) as controls. Morphology and semi-quantitative immunohistochemistry for collagen types I and II and procollagen IIA in the repair tissue were studied. Repair cartilage thickness was 2.89±1.5 mm and there was good basal integration between the repair cartilage, calcified cartilage and subchondral bone. Sixty five percent of the biopsies were predominantly fibrocartilage (mostly type I collagen and IIA procollagen), 15% were hyaline cartilage (mostly type II collagen), 17% were of mixed morphology and 3% were fibrous tissue (mostly type I collagen). Type II collagen and IIA procollagen were usually found in the lower regions near the bone and most type II collagen was present 30–60 months after treatment. The presence of type IIA procollagen in the repair tissue supports our hypothesis that this is indicative of a developing cartilage, with the ratio of type II collagen:procollagen IIA increasing from <2% in the first two years post-treatment to 30% three to five years after treatment. This suggests that cartilage repair tissue produced following ACI treatment, is likely to take some years to mature. [Copyright &y& Elsevier]