[Effect of different factors on the bone forming properties of recombinant BMPs]

The extent of BMP-induced new bone formation is mainly determined by the number of mesenchymal target cells in the recipient bed as well as by the biological half-life of the BMP molecules within the tissue. While the number of inducible cells is determined by the age and vascularization of the tissue, the retention time of the BMP molecules can be influenced. One possibility is the coupling of BMPs to suitable carriers, which significantly increases the osteoinductive effect. The reason for this is the physical binding of BMPs to the carrier material, which delays the resorption of the proteins. Other factors are the composition of the carrier materials, their structural stability, and possible dislocations of carrier particles. The local tissue concentration of BMPs can also be increased by an enhanced binding of the proteins to the extracellular matrix. A BMP-2 mutant (BMP-2xa) was produced by the specific modification of the amino acid sequence using recombinant technologies. BMP-2xa induces heterotopic bone formation at significantly lower concentrations than natural BMP-2. Furthermore, BMP-2xa-induced bone tissue possesses a higher bone density.