Article
The role of the bone morphogenetic proteins 2 and 7 in the repair of circumscribed cartilage lesions
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Published: | October 21, 2010 |
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Objective: Bone morphogenetic proteins are candidate growth factors with good potential in cartilage tissue engineering as well as cartilage repair. Although there is much known about the in vitro role of BMPs in cartilage metabolism reliable data about in vivo regulation in natural and surgically induced cartilage repair are still missing.
Methods: Lavage fluids of knee joints of 47 patients were prospectively collected between August 2006 and September 2007 during surgical therapy (UKF001822). 5 patients had no cartilage lesion and served as a control group, in case of the other 42 patients the cartilage defects were treated by microfracturing (19 patients) or by an Autologous Chondrocyte Implantation (23 patients). The average age of the patients with cartilage lesions was 42±10 years, the gender distribution was equal. The concentrations of BMP-2, and BMP-7 were determined by ELISA. Clinical status was evaluated using the IKDC and the Lysholm Score prior to and 1 year following cartilage regenerating surgery.
Results and conclusions: High level expression in the controls was found for BMP-2, concentrations of BMP-7 in the control group remained below detection levels. The concentrations of neither BMP-2 nor BMP-7 in the lavage fluids of knees with cartilage lesions were significantly different from the control group. Levels of BMP-7 did not change after surgical cartilage repair, whereas concentrations of BMP-2 (p<0.001) significantly increased after the intervention. The clinical outcome following cartilage regenerating surgery measured by the IKDC score increased after 1 year by 29% (p<0.001), and by 21% when evaluated by the Lysholm Score (p<0.01). The difference of both scores prior to the operation and after 1 year was used to quantitate the degree of improvement following surgery. This difference significantly correlated with initial BMP-2 (R=0.554, p<0.001) but not BMP-7 (R=0.031, n.s.) levels in the knee joints.
BMP-2 but seems to play an important role in surgically induced cartilage repair and might be suitable as a prognostic indicator for clinical outcome.