Composite Scaffolds with a Hydrohyapatite Spatial Gradient for Osteochondral Defect Repair

Osteochondral defects derived by traumatic injury or aging related disease are often associated with severe joint pain and progressive loss of joint functions for millions of people worldwide and represent a major challenge for the orthopedic community. Tissue engineering offers new therapeutic approach to repair the osteochondral defects, through the production of scaffolds manufactured to mimic their complex architecture, which consists of cartilage and bone layers. Composite scaffolds based on a PLLA polymeric matrix containing hydroxyapatite (HA) as a filler were prepared through a modified thermally induced phase separation (TIPS) protocol. A suspension was prepared by adding sieved HA particles to a ternary poly-L-lactic-acid (PLLA)/dioxane/water solution with a well defined solvent (dioxane) to non-solvent (water) ratio. A demixing protocol based on a well-defined temperature vs. time path was followed in order to achieve a porous structure with an architecture suitable for osteochondral defect repair. This result is obtained by imposing also a spatial gradient of hydroxyapatite on the scaffolds. Scaffolds were characterized via Scannning Electron Microscopy (SEM) and Micro-computed tomography (Micro-CT). Moreover, preliminary cell culture tests in static and dynamic conditions were successfully carried out.