Porous Hydrogels Prepared by Two-Step Gelation Method for Bone Regeneration

Hierarchical porous hydrogels possess advantageous characteristics that facilitate cell adhesion, promote tissue growth, and enhance angiogenesis and osteogenesis. In this study, porous composite hydrogels were successfully prepared by a two-step gelation method with sodium alginate (SA), gelatin (GEL), and calcium hydrogen phosphate (DCP) as the main components. The fabricated porous hydrogels initially featured small pores (approximately 60 μm), and gradually evolved to large pores (exceeding 250 μm) during the gradual degradation in the cellular microenvironment. In vitro cell culture experiments indicated that these hydrogels could enhance the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells due to the hierarchical porous structure and the incorporation of DCP. Subcutaneous implantation and cranial defect repair experiments in Sprague-Dawley rats further confirmed that the small initial pore size of hydrogel scaffolds can provide more sites for cell adhesion. Additionally, the gradual degradation to form large pores was conducive to cell/tissue growth and blood vessel formation, ultimately being beneficial for vascularized bone regeneration. In summary, this study proposes an innovative strategy for developing porous hydrogels with gradual degradation for functional bone regeneration.