INFLUENCE OF ETHYLENE OXIDE STERILIZATION ON NEW BONE FORMATION INDUCED BY BOVINE BONE MORPHOGENETIC PROTEIN

Abstract

Bone morphogenetic proteins (BMPs) have the capacity to induce and accelerate bone regeneration. Before experimental and clinical settings, BMP must be sterilized. Ethylene oxide (EO) gas sterilizations at different temperatures are commonly used but the effects of that on the osteoinductive capacity of BMP have been the subject of controversy. Here, we investigated the effects of three different EO sterilization methods on the osteoinductivity of partially purified native bovine BMP (bBMP). Gelatin capsules containing 3 mg of bBMP were sterilized as follows: (i) manually inside a dessicator with 12% EO spray (20°C, exposure time 2 h); (ii) with an EO gas sterilizer (Steri-Vac 4XL, temperature 29°C, exposure time 4 h 10 min, ethylene oxide concentration 860 mg/l); (iii) with an EO gas sterilizer (Steri-Vac 5XL, temperature 42°C, exposure time 3 h, ethylene oxide concentration 700 mg/l). The sterilization processes were monitored with samples of Bacillus subtilis (3M, Attest 1264). Osteoinductivity of bBMP was verified by bioassay. After 21 days of implantation of bBMP into the muscle pouches of mice, the animals were killed and new bone formation was measured radiographically and histologically. The EO sterilization techniques used did not significantly decrease the osteoinductive activity of BMP. It is concluded that commercial EO gas equipment sterilization is effective for sterilized BMP and does not decrease the osteoinductive capacity of bovine BMP.