Effect of radiosynovectomy with holmium-166 ferric hydroxide macroaggregate on adult equine cartilage.
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.


CONCLUSIONS
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.
Mäkelä
Olli T
OT
Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
Lammi
Mikko J
MJ
Uusitalo
Hannele
H
Viitanen
Minna
M
Hyttinen
Mika M
MM
Jurvelin
Jukka S
JS
Vuorio
Eero
E
Helminen
Heikki J
HJ
Tulamo
Riitta-Mari
RM
D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism; D006736:Horses; D006878:Hydroxides / Q000627:therapeutic use*; D013431:Sulfates / Q000493:pharmacokinetics; D013462:Sulfur Radioisotopes; D013582:Synovial Fluid / Q000378:metabolism; D013583:Synovial Membrane / Q000378:metabolism / Q000473:pathology*; D013585:Synovitis / Q000473:pathology* / Q000628:therapy*
D006025:Glycosaminoglycans; D006878:Hydroxides; D013431:Sulfates; D013462:Sulfur Radioisotopes; C483519:holmium-ferric hydroxide