Nano-pearl powder/chitosan-hyaluronic acid porous composite scaffold and preliminary study of its osteogenesis mechanism.

Bone tissue engineering using osteoinductive scaffolds has evolved into a promising approach for bone regeneration. Pearl powder has recently gained interest in bone regeneration due to their bioactive characteristics and favorable mechanical properties. In order to mimic bone tissue structurally and compositionally, chitosan-hyaluronic acid (C-HA) scaffolds containing nano-pearl powder (NPP) were fabricated in current study by using freeze-drying method. The microstructure, porosity, hydrophilia, and mechanical property of scaffolds were studied by scanning electron microscopy (SEM), mercury porosimeter, contact angles, and universal material experiment machine respectively. The crystal form of NPP, which was packed in scaffolds, was tested by X-ray diffraction (XRD), and the interaction between three constituents was studied by Fourier transformed infrared (FTIR). In the other hand, the biocompatibility, osteogenic characteristics, and osteogenic related gene expression of scaffolds were examined by cell counting kit-8 (CCK-8), alkaline phosphatase activity (ALP), RT-qPCR, and Western blotting. The results revealed that the NPP was successfully incorporated in the C-HA scaffolds. The hydrophilia and mechanical properties of scaffolds increased with NPP content, whereas the pore morphology was disturbed, especially for 25% scaffold. The scaffolds had a high porosity between 89% and 93%, and decreased slightly with the increase of NPP. Cell culture tests indicated that scaffolds with higher NPP proportion were beneficial for the proliferation and differentiation of MC3T3-E1 cells, and scaffolds with 10 wt% and 25 wt% nano-pearl powder were most effective. The differentiation might be promoted by upregulating the expression of Col αI, OCN, OPN and Runx2 genes. Therefore, the nano-pearl powder/chitosan-hyaluronic acid (NPP/C-HA) scaffolds may serve as a promising biomaterial for bone tissue engineering.