Cartilage Comeback

At some point it catches up with everyone. With increasing age joints and bones wear out. When for instance the cartilage, functioning as cushions between the joints becomes worn out, in most cases only the surgeon implanting a replacement part helps. Until now at least.

Scientists of the german Jena University – together with colleagues from France, England, Germany and Switzerland – are working on a tiny device that is being implanted in the joint and is supposed to trigger the regeneration of cartilage produced naturally in the body. The project OPHIS (Composite Phenotypic Triggers for Bone and Cartilage Repair) is subsidized with 4 Million Euro from the EU, of which 350.000 go to the Jena University. The project is running for four years.

Mostly Arthrosis and Arthritis patients will be able to profit by the results of the project, as the regeneration of the cartilage can be reactivated on smaller lacerations when the doctor recognizes the illnesses early enough. “Even though there are products like this on the market,” says Prof Dr Frank Müller, Materials Scientist of the Jena University. “None of them adheres actively with the bone underneath. This is exactly the improvement of our implant.”

The cellulose implant, of one centimeter diameter, is sponge-like and has two different surfaces. “The implant can substantially adhere to the bone through inorganic activation with calcium phosphate-nanoparticles on its lower surface,” explains the Jena Professor for Science and Technology of Surfaces and Interfaces.

“Scientists of another sub-project in Brighton in England apply growth factors on the opposite, porous surface of the implant to trigger the regeneration and ingrowth of cartilage cells.” Materials scientists of Jena University are able to produce the required porous surfaces with an especially developed process via ice templating. “For that purpose vegetal cellulose is being dissolved in water containing solvent and then deep-frozen at a defined speed,” says Prof Müller. “The ice crystals are so grown at a controllable temperature gradient. Afterwards the cellulose is being freeze-dried, so that little holes – pores – take the place of the ice cristals, as the water is being changed from a solid to a gaseous aggregate state. So a micro porous surface is created according to a given specification.” A facility especially for this process had been constructed in Jena.

Apart from cellulose implants composites from cellulose and collagen are being tested. These are even more promising, as the structural protein collagen is an important organic part of the connective tissue and thereby also of the bone and cartilage.

Moreover the scientists of the research project are aiming to fighting osteoporosis. Again tiny implants are supposed to stop the bone loss and to trigger the bone growth. These implants constist of bacterial cellulose, which is developed in co-operation with the research group of Dr Dana Kralisch at the Institute for Technical Chemistry and Environmental Chemistry at the Jena University. “Certain bacterial strains use glucose in their culture medium to produce cellulose,“ the project manager of Jena University explains. “When you influence the production by a shaking movement of the fluid, small pellets will form. These structures which are porous by nature are provided with defined protein sequences – so-called peptides – and are implanted into the bone. Bone forming cells migrate and the bone growth is re-stimulated.“

Contact:
Prof Dr Frank A. Müller
Institute of Materials Science and Technology
Friedrich-Schiller-University Jena
Löbdergraben 32
D-07743 Jena
Phone: 0049 3641 947750
Email: Frank.Mueller[at]uni-jena.de