A Biomimicking Polymeric Cryogel Scaffold for Repair of Critical-Sized Cranial Defect in a Rat Model

Mineralized polymeric cryogels with interconnective macroporous structure have demonstrated their potential as promising scaffolding material in bone tissue engineering. However, their capability in inducing osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro and osteogenesis in vivo has not been explored yet. In this work, the roles of the mineralized cryogel on osteogenesis are systematically studied. Mineralized macroporous poly(ethylene glycol)-co-2-hydroxyethyl methacrylate cryogel promotes osteogenic differentiation of rat MSCs, particularly in upregulating the activity of alkaline phosphatase (ALP, ∼5.7-folds) and expression of related osteogenic gene markers (ALP ∼16-folds, osteocalcin ∼133-folds) at 14 days. In vivo implantation reveals that mineralized cryogels could promote fast osteogenesis and angiogenesis in critical-sized cranial bone defect of a Sprague-Dawley rat model in 4 weeks. The adsorption, entrapment, and concentration of osteogenic growth factors (bone morphogenetic protein 2) and angiogenesis growth factor (vascular endothelial growth factor [VEGF]) in the matrices in vivo may possibly participate in the process of osteogenesis and angiogenesis. Notably, the adsorption of larger amount of VEGF in nonmineralized cryogels facilitates obvious angiogenesis and comparable osteogenesis in bone defect in 8 weeks. Graphical abstract [Figure: see text] Impact Statement The current work reported the fabrication and characterization of a biomimicking mineralized polymeric cryogel as scaffolding material in bone regeneration. In addition to its three dimensional porous structure and the osteogenic potential, this biomimicking scaffold was also found to enhance the adsorption of biochemical cues, which in turn greatly promoted the angiogenesis as well as the tissue regeneration.