The osteogenic effect of mesenchymal stem cells regulated by photo-crosslinked hydrogels with tunable elastic modulus

Biomimicry is the enduring pursuit in the field of bone implants, wherein bio-materials with adjustable elastic modulus and porosity, the same as natural bone, offer a novel strategy for developing and applying new bone repair materials. Conventional biomaterials are often used to repair bone defects without complete consideration of structural and functional osseointegration, leading to interface repair failure. In this study, organic-inorganic interpenetrating network technology was employed using varying amounts of nano-hydroxyapatite (nHAP) and methacrylated gelatin (GelMA) and osteogenic growth peptide (OGP) to construct biomimetic bones with low, medium, and high nano-hydroxyapatite content (GelMA-c-OGP/nHAP). As the concentration of nano-hydroxyapatite increases, comprehensive evaluations of the biomimetic materials were conducted using osteogenic ability tests, Micro-CT scans, nanoindentation tests, and mechanical tests. The developed biomimetic structural material exhibits well-controlled mechanical properties. Compared to natural bone trabeculae, this biomimetic material not only maintains the organic and inorganic ratio of natural bone but also demonstrates exceptional mechanical load-bearing capabilities. Additionaly，this scaffold exhibits good porosity and mechanical properties. It enhances cell adhesion, integrates perfectly with bone tissue, and demonstrates excellent osteogenic ability both in vitro and in vivo. This study lays the foundation for constructing biomimetic scaffolds with adjustable mechanical properties, presenting high prospects for applications in the field of tissue engineering.