Hierarchically structured biphasic scaffolds mimicking osteochondral tissue
Goal of the interdisciplinary project is to develop artificial osteochondral tissue which mimics the hierarchical architecture of the natural one as close as possible. For this purpose, biphasic materials consisting of polysaccharide gels like alginate or pectin and constituents of the extracellular matrices of bone (collagen type I, hydroxyapatite/HAP) and cartilage (hyaluronic acid/HYA), respectively, shall be developed which mimic many aspects of both tissues at the nanometre as well as the micrometre scale. The final scaffold has dimensions in the centimetre range and can be used for the regenerative therapy of osteochondral defects. Simultaneously to the formation of the solid calcium polysaccharide gels, parallel aligned pores are formed, running through the whole lengths of the scaffold. This might lead also to a partial alignment of the polysaccharide chains parallel to the direction of calcium diffusion, mimicking the fibre orientation of hyaline articular cartilage in the radial layer. By varying the polysaccharide concentration, the amount and type of calcium phosphate and the percentage of other constituents like collagen or HYA the diameter of the channel-like pores can be controlled and adjusted in a wide range, as well as the mechanical properties of the gels, mainly their stiffness. The process can be carried out completely under sterile conditions, allowing the embedding of living cells into the biphasic gels. This shall be used to include the investigation of the cellular behaviour in these novel biopolymer hydrogels – as an additional indicator for the adaptation of the constructs to the natural example and with the aim to finally mimic living osteochondral tissue in the lab.