Introduction: An osteochondral defect requires a tissue-mimicking scaffold due to the bone and cartilage layers' structural, physiological, and functional differences. This study aimed to develop a biomimetic bilayer scaffold by combining 3D-printed isosorbide-based novel CSMA-2 polymer and gelatin methacrylate (GelMA).
Methods: The osseous layer was fabricated by 3D printing CSMA-2 polymer with different hydroxyapatite (HA) filler concentrations using the Digital Light Processing (DLP) method. The gyroid structure was chosen due to its unique physical and mechanical properties. GelMA with optimised concentrations was prepared and light-cured on top of the 3D-printed CSMA-2 scaffold to create the chondral layer. Both material and solid scaffold characterisation were conducted to evaluate their chemical, mechanical, and rheological properties. In-vitro and in-vivo studies were performed to analyse the scaffold’s biocompatibility.
Results: Each scaffold layer demonstrated similar mechanical properties to native cancellous bone and cartilage tissue. The co-culture of MC3T3-E1 and ATDC5 cells on the bilayer scaffold showed the cells resided on their designated layers. The bilayer scaffolds maintained their structural integrity during the long-term dynamic cell culture period in a perfusion bioreactor. CSMA-2 layer and GelMA layer were able to support human adipose-derived stem cell (hADSC) osteogenic and chondrogenic differentiation. The in vivo result showed good biocompatibility, new bone growth, and satisfactory angiogenic properties of the scaffolds.
Discussion and Conclusions: The combination of 3D printed CSMA-2 and GelMA biomimetic bilayer scaffolds created the cartilage and bone tissue-specific environment. The bilayer scaffolds supported the growth of progenitor cells in a co-culture system and promoted stem cells' chondrogenic and osteogenic differentiation. It also had good mechanical properties and showed the potential to maintain its structural integrity during surgical implantation and integration with the recipient site.