Bioactive factors for bone tissue engineering.

Orthopaedic surgery is currently in the midst of a transformation from bone grafting and the use of bone graft substitutes to bone tissue engineering. Bioactive bone growth factors likely will play a particularly important role in this emerging field. This article will review the three leading strategies for using bioactive factors for bone tissue engineering: extraction and partial purification of growth factors, recombinant protein synthesis, and gene therapy. Preclinical and early clinical trial results with bone morphogenetic protein-2, bone morphogenetic protein-7 (osteogenic protein-1), and NeOsteo bovine bone protein extract will be reviewed. In addition, the current obstacles to clinical implementation of bone tissue engineering will be reviewed.