Novel and Unique Matrix Design for Osteochondral Tissue Engineering

ABSTRACTOsteochondral (OC) tissue is comprised of articular cartilage, the subchondral bone and the central cartilage-bone interface. To facilitate proper regeneration, an equally complex and multiphasic matrix must be used. Although mono-phasic and bi-phasic matrices were previously applied, they failed to establish the OC interface upon regeneration. In this study, we designed and developed a novel matrix with increasing pore volume from one end to other, along the matrix length. For this matrix polylactide-co-glycolide (PLGA) 85:15 microspheres were combined with a water-soluble porogen in a layer-by-layer fashion and thermally sintered. The resulting matrix was then porogen-leached to form a gradiently-porous structured matrix. The formation of this gradient pore structure was established using Micro-Computed Tomography (μCT) scanning. A biodegradable hydrogel was infiltrated into the structure to form a unique OC matrix where the microsphere and hydrogel phases co-exist with opposing gradients. When the individual phases are associated with osteogenic and chondrogenic growth factors, the structureinduced factor delivery might provide the spatially controlled factor delivery necessary to regenerate osteochondral tissue structure. Overall, we designed a gradient matrix system that is expected to support osteochondral tissue engineering while forming a seamless interface between the cartilage and the bone matrix.