INDUCTIVE PROPERTIES OF RECOMBINANT HUMAN BMP-2 PRODUCED IN A BACTERIAL EXPRESSION SYSTEM

Recombinant human BMP-2, produced in E. coli, refolded and concentrate d to a purity of more than 98%, has been demonstrated to be biological ly active. In vitro, amounts of 0.4 mu g BMP-2. or more induced new ca rtilage formation in 27 out of 47 samples of a neonatal muscle tissue assay, with chondroneogenesis occurring 14 days after a four-hour cont act between BMP-2 and the muscle tissue. In vivo, BMP-2 was implanted in the thigh muscle of ICR mice for a period of three weeks. Amounts o f 4 mu g BMP-2 and more showed heterotopic bone formation in 15 out of 17 samples. When BMP-2 was combined with a collagen carrier, amounts of 0.4 mu g protein or more induced heterotopic bone formation in 30 o ut of 33 samples four weeks after the implantation in the abdominal wa ll of Sprague-Dawley rats. The results show that the E. coli-derived B MP-2 was active in different assay systems in concentrations equal to those required with mammalian cell-expressed BMP-2. It could also be d emonstrated that a single morphogen (BMP-2) is enough to initiate the differentiation process associated with bone induction. The presented bacterial expression system also offers the opportunity to produce lar ge quantities of recombinant BMP-2 for clinical applications.