Bovine Tooth-derived Bone Morphogenetic Protein

Eight groups of dental tissues were mechanically dissected from the mandibles of one-year-old steers; they were then defatted and decalcified in HCl. The noncollagenous proteins were extracted with various solvents from collections of tissue and bio-assayed for osteo-inductive activity. Collectively, the hard tissue (dentin, enamel, and cementum) noncollagenous proteins were fractionated by molecular sieve chromatography, hydroxyapatite affinity chromatography, and ion exchange chromatography. Osteo-inductive activity of each protein fraction was determined by implantation in the quadriceps muscle pouch of mice. The quantity of bone was measured by computerized image analysis. From 71% to 83% of 41 implants of dental hard tissues induced bone formation. The quantity of bone was greater from unerupted than from erupted teeth. Dental soft tissues that had no osteo-inductive activity were rich in a 14-kDa protein, presumably matrix gamma-carboxyglutamic acid-rich proteins. Proteins with Mr of from 15 to 28 kDa were associated with osteo-inductive activity. Components with Mr greater than 28 kDa had no activity. These observations suggest that bovine teeth have a selection of osteo-inductive proteins that is comparable in range of MW to bovine bone morphogenetic protein.