BMP-2 can inhibit bone healing. Bone-chamber study in rabbits.

We came across a bone growing situation in which BMP-2 inhibits bone formation. Collagen sponges with BMP-2 were inserted in titanium bone chambers in rabbits. In this model, bone formation occurs spontaneously. With 2.4 and 0.12 micrograms BMP-2 per mm3 of the chamber volume, bone ingrowth was reduced to 16% and 42% of collagen controls, respectively. Sponges with 2.4 micrograms BMP-2 per mm3 that were placed in a similar titanium chamber in an intramuscular subfascial site induced bone formation in 4 cases of 5. The BMP-2 concentrations used are considered optimal for extraskeletal bone induction, and intramuscular sponges in rats all induced bone. The inhibitory effect is most likely model-related, but indicates unknown effects of BMP-2.