Simple Preparation and Bone Regeneration Effects of Poly(vinyl alcohol)-Resveratrol Self-Cross-Linked Hydrogels

Hydrogels have broad application prospects in bone repair. Pure poly(vinyl alcohol) (PVA) hydrogels have limited applications because of their low hardness and poor mechanical properties. This study found that resveratrol (Res) and PVA self-assembled and cross-linked through the formation of strong hydrogen bonds after freeze-thawing, forming an easily available PVA-Res supramolecular hydrogel through a green process. PVA-Res hydrogels with different Res wt %:10 wt % PVA ratios were prepared through freeze-thawing and designated as 0.4, 1.2, and 2.0 wt % PVA-Res hydrogels. Rheological studies demonstrated that the viscoelastic modulus of the PVA-Res hydrogels was significantly improved compared to pure PVA hydrogels. The viscoelastic modulus G' of 1.2% PVA-Res hydrogel was 2299 Pa, which was 8.5-fold that of the pure PVA hydrogel. We conducted a study on cell proliferation and osteogenic differentiation using MC3T3-E1 (preosteoblasts from newborn mouse calvaria). The results showed that the 0.4% PVA-Res hydrogel promotes alkaline phosphatase activity and mineral deposition. Real-time quantitative PCR (RT-qPCR) analysis demonstrated that the 0.4% PVA-Res hydrogel upregulated the expression of osteogenic differentiation-related genes (BMP-9, OCN, and ALP). Furthermore, RT-qPCR and flow cytometry demonstrated that the 0.4% PVA-Res hydrogel could effectively promote the M2 transformation and polarization of mouse mononuclear macrophage leukemia cells (Raw 264.7). The expression of related genes, such as Arg-1 and CD206, significantly increased, whereas that of M1 polarization-related genes, such as iNOS and TNF-α, significantly decreased. In summary, PVA-Res supramolecular hydrogels are potential materials for use in bone repair.