(OP 311) Versatile Polyurethane Scaffold Material for Tissue Engineering

A set of 2K-polyurethane-systems as scaffolds for regenerative medicine has been developed. Its properties can be customized in a broad range to address different tissues. For the regeneration of soft tissues (ranging from fat to cartilage) formulations have been chosen that can be cast to an open-pore foam without a skin. The polymers are made from aliphatic diisocyanates and different polyester-polyols. The porosity and the surface properties can be adjusted by biocompatible additives. If hard tissues like bone shall be reconstructed, the material can be filled with up to 75% of ceramic particles (preferably HAP or TCP). Scaffolds are built up by dispensor techniques. The mechanical properties of these scaffolds can be varied by means of the ceramic content. The Young's modulus is between 900 and 1600 MPa, the flexural strength between 5 and 10 MPa. These values are comparable with those of trabecular bone. Steam sterilization of both materials is possible. The degradation time of the polyurethanes can be adjusted from several months up to two years by variation of the polyol composition, the diisocyanate and fillers. A key factor is the hydro-philicity of the building blocks. The pH during the degradation is within a narrow range, even if the medium is not changed. No toxic degradation products are observed. The compatibility with differents cells (cartilage, bone, fat, nucleus pulposus) and tissues has been proven. The constructs are well integrated into the surrounding tissues at different implantations sites and induced the ingrowth of bloodvessels.