Ga. Loredo et al., REGULATION OF GLYCOSAMINOGLYCAN METABOLISM BY BONE MORPHOGENETIC PROTEIN-2 IN EQUINE CARTILAGE EXPLANT CULTURES, American journal of veterinary research, 57(4), 1996, pp. 554-559
Objective-To investigate whether recombinant human bone morphogenetic
protein-2 (rhBMP-2) regulates glycosaminoglycan (GAG) synthesis and re
lease from equine articular cartilage explant cultures. Design-Equine
articular cartilage explants were maintained in vitro for 7 days in th
e presence of 0 (control), 1, 10, or 100 ng of rhBMP-2/ml. Synthesis a
nd release of GAG were assessed as measures of production and degradat
ion of the extracellular matrix, respectively. Animals-6 horses (age r
ange, 2 to 25 years old) without clinically detectable musculoskeletal
abnormalities. Procedure-Rate of synthesis of GAG was assessed by inc
orporation of [S-35]sulfate during the final 24 hours of the 7-day inc
ubation period. Release of GAG was assessed on days 3, 6, and 7, using
1,9-dimethylmethylene blue. Results-Explants from all 6 horses had a
significant (P = 0.05) increase in release of GAG in response to incub
ation with 100 ng of rhBMP-2/ml. There was a significant (P = 0.05) de
crease in GAG synthesis in explants from only 2 of the 6 horses at the
same concentration of rhBMP-2. There was no significant age correlati
on between responsive and nonresponsive horses. Conclusions-A concentr
ation of 100 ng of rhBMP-2/ml stimulates GAG release from explant cult
ures of equine articular cartilage. The data suggest that bone morphog
enetic proteins may be potential regulators of equine cartilage degrad
ation and repair. Clinical Relevance-Surgical procedures that damage s
ubchondral bone may stimulate generation of improved cartilage-like ti
ssue. It is, therefore, crucial to understand how bone-derived factors
may influence cartilage metabolism in horses.