Osteoarthritis is a degenerative disorder resulting from breakdown of articular cartilage. Previous work has shown bone morphogenic
protein-7 has a potential protective effect on cartilage during the development of osteoarthritis. The purpose of this study
was to determine whether bone morphogenic protein-7 could decrease the amount of cartilage degradation in preexisting osteoarthritis.
The rabbit ACLT model was used as a model of osteoarthritis. Bone morphogenic protein-7 was delivered via Alzet osmotic pump
to the joint 4 weeks after anterior cruciate ligament transection; thus cartilage injury was preexisting. The experimental
group showed less cartilage degradation than the controls, with an average Outerbridge score of 1.9 versus 2.6 for the controls.
Histomorphometry showed a trend toward less cartilage degradation in the bone morphogenic protein-7 group when compared with
controls. Semiquantitative real-time polymerase chain reaction showed a considerably greater expression of aggrecan in the
bone morphogenic protein-7-treated cartilage when compared with controls and less expression of matrix metalloproteinase-3
and matrix metalloproteinase-13, important catabolic mediators. The synovial tissue of the experimental group also showed
considerably less expression of matrix metalloproteinase-3, matrix metalloproteinase-13, and aggrecanase. These results indicate
bone morphogenic protein-7 may reduce degradation of articular cartilage in osteoarthritis.
Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest,
patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
Each author certifies that his or her institution has approved the animal protocol for this investigation and that all investigations
were conducted in conformity with ethical principles of research.