Demineralized bone matrix and bone morphogenetic protein have been use
d clinically to accelerate bone regeneration. However, the best method
of sterilization has been the subject, bf controversy. Some investiga
tors have used ethylene oxide, but others have reported that; doses ad
equate for sterilization destroyed the osteoinductivity of demineraliz
ed bone matrix and that gamma irradiation was less harmful in this res
pect. We used partially purified bone morphogenetic protein and type-I
collagen to investigate the effects of sterilization by ethylene oxid
e and gamma irradiation on the activity of bone morphogenetic protein.
Osteoinductivity was reduced considerably after sterilization by gamm
a irradiation at 2.5 Mrad and by ethylene oxide at 37 degrees C for 4
hours and at 55 degrees C for 1 hour; however, the reduction induced b
y ethylene oxide at 29 degrees C for 5 hours was about half of the con
trol values. This study showed that ethylene oxide at 29 degrees C for
5 hours can be used clinically for sterilization of bone morphogeneti
c protein. We also investigated the effect of gamma irradiation on bon
e morphogenetic protein and the collagen carrier separately and found
that collagen was far more labile than bone morphogenetic protein.