Bone morphogenetic proteins and tendon repair

Bone repair is controlled by signalling proteins as well as mechanical stim uli. Bone morphogenetic proteins (BMPs), implanted or injected into a fract ure site, can enhance bone healing, and so can mechanical stimulation. Poss ibly. mechanical signals can alter BMP expression, but furthermore, tissue differentiation initiated by an implanted BMP could be guided into the requ ired direction by mechanical signals. Mechanical stimulation also has profo und effects on tendon repair. We studied the effects of 3 different BMPs in a rat tendon repair model. One of these, osteogenic protein 1 (OP-1) induc ed bone formation in the tendon at the expense of mechanical strength and t hus overrode any mechanical control system. On the other hand, cartilage de rived morphogenetic protein 1 and 2 (CDMP-1 and -2) both made the tendon ca llus bigger and stronger at an early time point.