Regeneration of Mechanically Enhanced Tissue-Engineered Cartilage Based on the Decalcified Bone Matrix Framework

Human decalcified bone matrix (HDBM) is a framework with a porous structure and good biocompatibility. Nevertheless, its oversized pores lead to massive cell loss when seeding chondrocytes directly over it. Gelatin (GT) is a type of protein obtained by partial hydrolysis of collagen. The GT scaffold can be prepared from the GT solution through freeze-drying. More importantly, the pore size of the GT scaffold can be controlled by optimizing the concentration of the GT solution. Similarly, when different concentrations of gelatin are combined with HDBM and then freeze-dried, the pore size of the HDBM can be modified to different degrees. In this study, the HDBM framework was modified with 0.3, 0.6, and 0.9%GT, resulting in an improved pore size and adhesion rate. Results showed that the HDBM framework with 0.6%GT (HDBM-0.6%GT) had an average pore size of 200 μm, which was more suitable for chondrocyte seeding. Additionally, our study validated that porcine decalcified bone matrix (PDBM) had a proper pore structure. Chondrocytes were in vitro seeded on the three frameworks for 4 weeks and then implanted in nude mice and autologous goats, respectively. The in vivo cartilage regeneration results showed that HDBM-0.6%GT and PDBM frameworks compensated for the oversized pores of the HDBM framework. Moreover, they showed successfully regenerated more mature cartilage tissue with a certain shape in animals.