Induced tissue integration of bone implants by coating with bone selective RGD-peptides in vitro and in vivo studies

The optimal function of medical implant materials used in tissue substitution is often limited due to its healing properties. This effect is linked to reduced interactions of the implants with the surrounding tissue. Implant surfaces biologically functionalized with arginine-glycine-aspartic acid (RGD) peptides, a class of cellular adhesion factors, are described in this paper. The RGD-peptides are either bound via bovine serum albumin linking on culture plastic dishes as a model surface or via acrylic acid coupling on PMMA surface as a potential implant material. Resulting functionalized surfaces aquire the capability to bind cultured osteoblasts in high levels and show high proliferation rates in vitro. These results are observed for osteoblast cultures as well as from different species with different preparation procedures. A critical minimum distance between the bioactive portion of the RGD-peptides and the implant surface of 3.0-3.5 nm is crucial for the induction of an optimum cell binding process. In vivo animal studies in the rabbit show that newly formed bone tissue generated a direct contact with the RGD-peptide coated implants. In contrast uncoated implants are separated from newly formed bone tissue by a fibrous tissue layer thereby preventing the formation of a direct implant-bone bonding.