A biopolymer-reinforced collagen hydrogel mimicking the 3D mechanical microenvironment promotes osteogenic differentiation via mechanotransduction

Mechanical forces play a critical role in the oral and maxillofacial region. Understanding cellular responses to mechanical forces is essential. However, current mechanobiological studies are largely confined to 2D cultures, which poorly represent native 3D contexts. Although hydrogels offer promise for 3D studies, integrating high-magnitude mechanical stretch with biocompatibility remains challenging. This study developed a novel collagen-based gelatin/cellulose nanocrystal/alginate (C-GCA) hydrogel. The elongation at break of the hydrogel reaches 95.4%, demonstrating excellent tensile properties, which is attributed to the reinforcing effect of CNCs and SA. Concurrently, the presence of collagen and gelatin confers favorable biocompatibility to the hydrogel (cell viability exceeding 95%). Crucially, the biological responses of Periodontal ligament stem cells (PDLSCs) laden in the C-GCA hydrogel-based 3D microenvironment were strain-dependent. Under 20% tensile strain, the expression of osteogenesis-related genes, namely RUNX-2 , OSX , COL1A1 , and OPN , was 3.1, 4.1, 1.7 and 2.8 times that of the control group, respectively. Meanwhile, the cell projection area increased by 1.38 folds, and the apoptosis rate reduced by 45.5%. Overall, the C-GCA hydrogel not only provides a solid foundation for a deeper understanding of the mechanisms of mechanostimulation in the oral and maxillofacial regions but also offers new strategies for the biomedical material design.