The bone morphogenetic proteins (BMPs) belong to a unique group of proteins that includes the growth factor TGF-β. BMPs play important roles in cell differentiation, cell proliferation, and inhibition of cell growth. They also participate in the maturation of several cell types, depending on the microenvironment and interactions with other regulatory factors. Depending on their concentration gradient, the BMPs can attract various types of cells and act as chemotactic, mitogenic, or differentiation agents. BMPs can interfere with cell proliferation and the formation of cartilage and bone. In addition, BMPs can induce the differentiation of mesenchymal progenitor cells into various cell types, including chondroblasts and osteoblasts.
Bone morphogenetic proteins (BMPs) regulate many mammalian physiologic and pathophysiologic processes. These proteins bind with the kinase receptors BMPR-I and BMPR-II, thereby activating Smad transcription factor.
BMP-2 like other bone morphogenetic proteins, plays an important role in the development of bone and cartilage. It is involved in the hedgehog pathway, TGF beta signaling pathway, and in cytokine-cytokine receptor interaction. It is involved also in cardiac cell differentiation and epithelial to mesenchymal transition.
BMP-2 and BMP-7 are osteoinductive BMPs: they have been demonstrated to potently induce osteoblast differentiationin a variety of cell types. Bone morphogenetic protein 2 is shown to stimulate the production of bone.Recombinant human protein (rhBMP-2) is currently available for orthopaedic usage in the United States. Implantation of BMP-2 in a collagen sponge induces new bone formation and can be used for the treatment of bony defects, delayed union, and non-union.
Bone morphogenetic protein 2 has also found its way into the field of Dentistry. Oral and Maxillofacial Surgery and Implant Dentistry in particular have benefited dramatically from commercially available BMP-2.The use of dual tapered threaded fusion cages and recombinant human bone morphogenetic protein-2 on an absorbable collagen sponge obtained and maintained intervertebral spinal fusion, improved clinical outcomes, and reduced pain after anterior lumbar interbody arthrodesis in patients with degenerative lumbar disc disease. As an adjuvant to allograft bone or as a replacement for harvested autograft, bone morphogenetic proteins (BMPs) appear to improve fusion rates after spinal arthrodesis in both animal models and humans, while reducing the donor-site morbidity previously associated with such procedures.
A study published in 2011 noted "reports of frequent and occasionally catastrophic complications associated with use of [BMP-2] in spinal fusion surgeries", with a level of risk far in excess of estimates reported in earlier studies.