A silk fibroin/chitosan/nanohydroxyapatite biomimetic bone scaffold combined with autologous concentrated growth factor promotes the proliferation and osteogenic differentiation of BMSCs and repair of critical bone defects.

Purpose: With the goal of increasing the translational efficiency of bone tissue engineering for practical clinical applications, biomimetic composite scaffolds combined with autologous endogenous growth factors for repairing bone defects have become a current research hotspot. In this study, we prepared a silk fibroin/chitosan/nanohydroxyapatite (SF/CS/nHA) composite biomimetic scaffold and then combined it with autologous concentrated growth factor (CGF) to explore the effect of this combination on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and the efficiency of repairing critical radial defects.

Methods: Three kinds of SF/CS/nHA composite biomimetic scaffolds with mass fractions of 3%, 4%, and 5% were prepared by vacuum freeze-drying and chemical cross-linking methods, and the characteristics of the scaffolds were evaluated. In vitro, BMSCs were seeded on SF/CS/nHA scaffolds, and then CGF was added. The morphology and proliferation of BMSCs were evaluated by live-dead staining, phalloidin staining, and CCK-8 assays. ALP staining, alizarin red staining, cellular immunofluorescence, RT-PCR, and Western blotting were used to detect the osteogenic differentiation of BMSCs. In vivo, a rabbit radius critical bone defect model was constructed, and the SF/CS/nHA-BMSC scaffold cell complex combined with CGF was implanted. The effect on bone defect repair was evaluated by 3D CT scanning, HE staining, Masson staining, and immunohistochemistry.

Results: The characteristics of 4% SF/CS/nHA were the most suitable for repairing bone defects. In vitro, the SF/CS/nHA combined CGF group showed better adhesion, cell morphology, proliferation, and osteogenic differentiation of BMSCs than the other groups (P < 0.05 for all). In vivo imaging examination and histological analysis demonstrated that the SF/CS/nHA scaffold combined with CGF had better efficiency in bone defect repair than the other scaffolds (P < 0.05 for all).

Conclusions: A SF/CS/nHA composite biomimetic bone scaffold combined with autologous CGF promoted the proliferation and osteogenic differentiation of BMSCs in vitro and improved the repair efficiency of critical bone defects in vivo. This combination may have the potential for clinical translation due to its excellent biocompatibility.