Stimulation of Bone Growth on Implants by Integrin Ligands

A successful biointegration of orthopedic and craniofacial implants requires a strong mechanical interaction between the surface of the artificial material and the surrounding natural bone tissue. Osseointegration of implants is known to be a biological process that occurs by formation of new peri-implant bone in direct contact with the synthetic surface. Mimicking the physiological adhesion process of osteoblasts to the extracellular matrix (ECM), by coating of implant surfaces with specific cell-adhesive molecules, was proven to enhance osteoblast adhesion in vitro and to accelerate osseointegration of implants in vivo. Cell adhesion is mediated by integrins, a class of heterodimeric transmembrane cell receptors that bind selectively to different proteins of the ECM and transduce information to the nucleus through cytoplasmic signaling pathways. The pep-tide sequence Arg-Gly-Asp (RGD), is by far the most effective and extensively studied ligand to promote osteoblast adhesion and proliferation on implants through integrin stimulation. The biofunctionalization of different surfaces with RGD peptides and mimetics has resulted in major improvements in bone implant technology.