Biologische Beschichtung von Implantaten mit rhBMP-2
Biocoating of implants with rhBMP-2
A concept and methodology were developed for the direct biocoating of implantable metals, like titanium and stainless steel, with bioactive factors such as bone morphogenetic proteins (BMP) for future application as cementless bone prostheses. Recombinant human BMP-2 (rhBMP-2) was expressed in E. coli and purified in biologically active form. Small electropolished titanium plates were “surface-enhanced” by a novel treatment with chromosulfuric acid and then coated with rhBMP-2. Treatment with chromosulfuric acid led to a very hydrophilic surface with a five-fold higher binding capacity for protein. In vivo testing was initated employing a periostal flap test model in rabbits. In the animal model it could be shown that the biocoated implants are non-toxic and the overall in vivo biological activity of rhBMP-2 biocoated implants (insoluble BMP-2) is so high that it is comparable to that of soluble rhBMP-2 controls, only that in the latter case the BMP effect is neither limited nor targeted and poses the danger of ectopic bone formation. We conclude that surfaces of biomaterials can be tailored by our method in such a way that a selective and specific interaction (“biological recognition”) with the target tissue can be induced by immobilized rhBMP-2 with minimal danger of ectopic bone formation and without eliciting a significant inflammatory response.
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