Mineralized chitin nanocrystals enhance osteoinductive ability of chitosan 3D porous biohybrid scaffolds for bone tissue regeneration

The loss of alveolar bone due to periodontitis has high worldwide prevalence, and Tissue Engineering (TE) emerges as an alternative to replace autologous bone grafting. Herein, TE fundamentals were applied to mimic bone extracellular matrix (ECM) and cells microenvironment. First, biomimetic hydroxyapatite-based mineralized chitin nanocrystals (MCHNC) from both alpha or beta isoforms were synthesized, showing excellent in vitro biocompatibility and osteoinductive properties over human adipose-derived mesenchymal stem cells (hASCs) osteogenic differentiation. Then, biohybrid 3D porous biomaterials were obtained by combining MCHNC as inorganic nanoparticles, chitosan (CS) as organic matrix and hASCs spheroids. The biohybrids showed an improvement of the mechanical properties over non-mineralized scaffolds. Furthermore, they presented high in vitro biocompatibility and bioactivity, providing an adequate microenvironment for cells. In particular, CS/MβCHNC biomaterial presented the greatest mechanical properties (191 ± 10 kPa). Additionally, the incorporation of MβCHNC provided the biomaterial with osteoinductive character, since hASCs showed increased ALP activity (3.5-fold) and higher matrix mineralization (26.3-fold), even when cultured in standard cell culture medium. Finally, the osteospheroids showed very good integration into the CS/MβCHNC biomaterial, with great migration and colonization of viable cells. These findings demonstrate the potential of CS/MβCHNC biomaterial for TE as alveolar bone regeneration.