TISSUE ENGINEERING, MORPHOGENESIS, AND REGENERATION OF THE PERIODONTAL TISSUES BY BONE MORPHOGENETIC PROTEINS

Tissue engineering is the emerging field of science developing techniq ues for fabrication of new tissues for replacement based on principles of cell and developmental biology and biomaterials. Morphogenesis is the cascade of pattern formation and the attainment of form of the var ious organs and the organism as a whole. The periodontium consists of the periodontal ligament, cementum, and alveolar bone. Bone has consid erable potential for regeneration and therefore is a prototypic model for tissue engineering. The three main ingredients for tissue engineer ing are regulatory signals, responding stem cells, and extracellular m atrix. Recent advances in molecular biology of the bone morphogenetic proteins (BMPs) have set the stage for tissue engineering of bone and related tissues, including the periodontium. Bone-derived BMPs, with a collagenous matrix as carrier, induced cementum and alveolar bone reg eneration in surgically created furcation defects in the primate. It i s noteworthy that there was morphogenesis of periodontal ligament and a faithful insertion of: Sharpey's fibers into cementum, In the same f urcation model, recombinant human osteogenic protein-1 (rhOP-1, also k nown as BMP-7), in conjunction with the collagenous carrier, induced e xtensive cementogenesis with insertion of Sharpey's fibers into the ne wly formed cementum. The observation that BMPs induce cementogenesis a nd periodontal ligament formation indicates that these proteins may ha ve multiple functions in vivo not limited to cartilage and bone induct ion. The rapid advances in the molecular biology of BMPs and their rec eptors bode well for novel strategies to engineer the regeneration of the periodontal tissues.