A Biomimicking Polymeric Cryogel Scaffold for Repair of Critical Sized Cranial Defect in 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 MSCs in vitro and osteogenesis in vivo have 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 mesenchymal stem cells (rMSCs), particularly in upregulating the activity of alkaline phosphatase (ALP, ~5.7 folds) and expression of related osteogenic gene markers (ALP ~16 folds, osteocalcin (OCN) ~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, or BMP2) and angiogenesis growth factor (vascular endothelial growth factor, or 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 non-mineralized cryogels facilitate obvious angiogenesis and comparable osteogenesis in bone defect in 8 weeks.