Composite cryogel of gelatin/nanofibrillated cellulose/partially demineralized chitin with potential for bone tissue...

Fabrication of macroporous scaffolds with favorable mechanical and biological properties based on natural polysaccharides embedding inorganic components has emerged as a promising alternative for bone regeneration. We hypothesized that partially demineralized chitin containing natural calcium phosphate with suitable mechanical strength as the inorganic component is more favorable for this purpose than commonly used nano-hydroxyapatite (nHA). Therefore, a macroporous cryogel scaffold composed of gelatin (G), nanofibrillated cellulose (NFC), and partially demineralized chitin (PDCh), chemically crosslinked with oxidized dextran (ODex), was developed in this study. The scaffold exhibited suitable aqueous solvent absorption, with a controlled degradation and proper calcium phosphate concentration and a 50-500 μm pore size distribution that promoted cell growth and osteogenesis. Incorporating PDCh provided a high surface-to-volume ratio and significantly enhanced the scaffold's mechanical properties with a compressive strength of 315.4 kPa, suitable for cancellous bone regeneration. Moreover, the presence of natural calcium phosphate in PDCh led to superior biocompatibility and bone differentiation in human mesenchymal stem cells (hMSCs), as evidenced by an increase in calcium deposition, higher alkaline phosphatase (ALP) activity, and an increase in collagen-type 1 and osteocalcin gene expression compared to scaffold containing nHA. These results demonstrated the promising potential of gelatin/nanofibrillated cellulose/PDCh cryogel scaffolds for bone tissue engineering applications.