NOVEL BIPHASIC SCAFFOLDS FOR OSTEOCHONDRAL UNIT (OCU) REPAIR

Direct printed absorbable metallic implants have emerged as a promising solution for bone regeneration. Additively manufactured porous metal alloys based on iron, magnesium, or zinc, offer unique advantages in mimicking bone architecture and mechanical properties. This talk will briefly introduce the potential of magnesium alloy WE43 for bone regeneration, based on data from in vitro studies and a canine model. Porous WE43 scaffolds showed a high, 36% ± 19%, absorption rate within the first four weeks upon implantation. However, newly formed bony tissue was detectable early, with substantial mineralized bone detected after 12 weeks, underscoring WE43's potential for bone defect repair. As osteochondral defects present a significant challenge in Orthopaedic surgery due to the complex nature of the tissue interface, the talk will further introduce a novel approach to OCU repair using biodegradable bilayered scaffolds. Our innovative scaffold combines a photocured chondroitin sulfate (CS) hydrogel for cartilage repair with a porous pure zinc (Zn) scaffold for bone regeneration. These materials can be customized to create multi-scale geometries with interconnected porous structures, facilitating vascularization and bone cell adhesion while providing tunable absorption properties. The mechanical properties of these scaffolds closely mimic those of native tissues, with the CS hydrogel exhibiting a compressive strength of 82 kPa and the porous Zn scaffold demonstrating a yield strength of 11 MPa and stiffness of 0.8 GPa. These characteristics provide crucial support during the healing process. In vivo studies in a porcine model revealed promising results for osteochondral regeneration. The bilayered scaffold facilitated simultaneous bone and cartilage regeneration, resulting in a smoother cartilage surface, more hyaline-like cartilage, and superior integration into adjacent host tissue. Furthermore, the bilayered scaffold promoted both chondrogenic and osteogenic differentiation of bone marrow stem cells. Our findings demonstrate the potential of innovative bilayered scaffolds for osteochondral unit repair. The combination of CS hydrogel and porous Zn scaffold shows promise in addressing the unique challenges of cartilage and bone regeneration. Future research should focus on optimizing the degradation kinetics of these materials, particularly controlling initial bulk absorption through surface modifications. The promising results from both in vitro and in vivo studies warrant further investigation into the long-term efficacy and safety of these scaffolds for osteochondral regeneration in humans.