Responsive Gel Promotes Bone Growth on Implants

Researchers at Uppsala University (Sweden) and Institut Laue-Langevin (Grenoble, France) succeeded in binding bone morphogenetic protein 2 (BMP-2) to hyaluronic acid—an anionic, nonsulfated glycosaminoglycan that is one of the chief components of the extracellular matrix (ECM)—with covalently linked bisphosphonate (BP) ligands. The result was a stable hydrogel that they used to coat titanium implants. They also demonstrated that the layer of BMP-2 was stable in water, but could be released slowly by adding solutions that contain calcium ions.

The gel layers, a few millionths of a millimeter thick, were characterized using neutron reflection at the ILL, a technique that provides a detailed picture of what happens at a surface and to track the amount of protein present. The researchers have also launched in-vivo trials in collaboration with the Swedish Agricultural University (SLU; Uppsala, Sweden) of similar materials for metal implants in rabbits. The ongoing studies will provide a step towards transfer of the results to clinical applications. The study was published early online on March 31, 2014, in Advanced Engineering Materials.

“We envisage that the materials will be used in medicine to modulate the healing process in bone,” said Associate Professor Dmitri Ossipov, PhD, of the Uppsala department of medicinal chemistry. “Neutrons are an ideal tool to understand the interactions of metal surfaces, polysaccharide biopolymers, and proteins thanks to a contrast matching technique that highlights only the protein components at the interface.”

“Neutron scattering techniques are increasingly relevant to optimize bio-materials and to study systems that relate to health,” said Giovanna Fragneto, PhD, of the ILL. “The importance of combining conventional laboratory studies with those at a large scale facility to give a complete picture of a process was proven once more.”

Related Links:
Uppsala University
Institut Laue-Langevin
Swedish Agricultural University