RT Journal Article SR Electronic T1 Effect of radiosynovectomy with holmium-166 ferric hydroxide macroaggregate on adult equine cartilage. JF The Journal of Rheumatology JO J Rheumatol FD The Journal of Rheumatology SP 321 OP 328 VO 31 IS 2 A1 Olli T Mäkelä A1 Mikko J Lammi A1 Hannele Uusitalo A1 Minna Viitanen A1 Mika M Hyttinen A1 Jukka S Jurvelin A1 Eero Vuorio A1 Heikki J Helminen A1 Riitta-Mari Tulamo YR 2004 UL http://www.jrheum.org/content/31/2/321.abstract AB OBJECTIVE: To analyze the effect of radiosynovectomy with holmium-166 ferric hydroxide macroaggregate (166Ho-FHMA) on articular cartilage in 6 adult horses. METHODS: Arthritic changes and mechanical properties of articular cartilage were evaluated with arthroscopy and postmortem microscopic analyses. Glycosaminoglycan content was measured by safranin-O staining combined with digital densitometry, uronic acid analyses, and dimethylene blue binding assay. 35S-sulfate labeling and autoradiography were used to localize proteoglycan synthesis and to characterize proteoglycan structures using SDS-agarose gel electrophoresis. Northern hybridizations were performed to measure the mRNA levels for aggrecan and pro-a1(II) collagen in cartilage samples. RESULTS: Histological signs of degeneration were present in the articular cartilage of both control and radiosynovectomized equine joints. Radiosynovectomy did not aggravate degenerative changes or significantly alter the matrix glycosaminoglycan content. A slightly decreased size of proteoglycan monomers was observed 2 months after 166Ho-FHMA radiosynovectomy. Tissue analysis of extracted proteoglycans revealed lower 35S incorporation after radiosynovectomy, but corresponding changes could not be observed in aggrecan mRNA levels. Transient downregulation of pro-a1(II) collagen mRNA transcription was observed 5 days after 166Ho-FHMA radiosynovectomy. CONCLUSION: 166Ho-FHMA treatment did not markedly affect the composition or morphology of adult articular cartilage showing mild degeneration. However, minor degradation of proteoglycan monomers and transient downregulation of pro-a1(II) collagen mRNA were observed.