Microfracture and bone morphogenetic protein 7 (BMP-7) synergistically stimulate articular cartilage repair.
OBJECTIVE
Microfracture is used to treat articular cartilage injuries, but leads to the formation of fibrocartilage rather than native hyaline articular cartilage. Since bone morphogenetic protein 7 (BMP-7) induces cartilage differentiation, we hypothesized that the addition of the morphogen would improve the repair tissue generated by microfracture. We determined the effects of these two treatments alone and in combination on the quality and quantity of repair tissue formed in a model of full-thickness articular cartilage injury in adolescent rabbits.


METHODS
Full-thickness defects were made in the articular cartilage of the patellar grooves of forty, 15-week-old rabbits. Eight animals were then assigned to (1) no further treatment (control), (2) microfracture, (3) BMP-7, (4) microfracture with BMP-7 in a collagen sponge (combination treatment), and (5) microfracture with a collagen sponge. Animals were sacrificed after 24 weeks at 39 weeks of age. The extent of healing was quantitated by determining the thickness and the surface area of the repair tissue. The quality of the repair tissue was determined by grading specimens using the International Cartilage Repair Society Visual Histological Assessment Scale.


RESULTS
Compared to controls, BMP-7 alone increased the amount of repair tissue without affecting the quality of repair tissue. Microfracture improved both the quantity and surface smoothness of repair tissue. Compared to either single treatment, the combination of microfracture and BMP-7 increased both the quality and quantity of repair tissue.


CONCLUSIONS
Microfracture and BMP-7 act synergistically to stimulate cartilage repair, leading to larger amounts of repair tissue that more closely resembles native hyaline articular cartilage.
Kuo
A C
AC
The Center for Tissue Regeneration and Repair, Department of Orthopaedic Surgery, University of California, Davis, 4635 Second Avenue, Room 2000, Sacramento, CA 95817, USA. alfred.kuo@ucdmc.ucdavis.edu <alfred.kuo@ucdmc.ucdavis.edu>
Rodrigo
J J
JJ
Reddi
A H
AH
Curtiss
S
S
Grotkopp
E
E
Chiu
M
M
D000818:Animals; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000627:therapeutic use*; D002358:Cartilage, Articular / Q000473:pathology / Q000601:surgery*; D003094:Collagen / Q000008:administration & dosage; D003131:Combined Modality Therapy / Q000379:methods; D004195:Disease Models, Animal; D050724:Fractures, Cartilage / Q000188:drug therapy / Q000601:surgery / Q000628:therapy*; D006614:Hindlimb; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D011817:Rabbits; D011994:Recombinant Proteins / Q000627:therapeutic use*; D016212:Transforming Growth Factor beta / Q000627:therapeutic use*; D016896:Treatment Outcome; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology
D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D003094:Collagen