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The network structure of a three-dimensional hydrogel scaffold dominates its performance such as mechanical strength, mass transport capacity, degradation rate and subsequent cellular behavior. The hydrogels scaffolds with interpenetrating polymeric network (IPN) structure have an advantage over the individual component gels and could simulate partly the structure of native extracellular matrix of cartilage tissue. In this study, to develop perfect cartilage tissue engineering scaffolds, IPN hydrogels of collagen/chondroitin sulfate/hyaluronan were prepared via two simultaneous processes of collagen self-assembly and cross linking polymerization of chondroitin sulfate-methacrylate (CSMA) and hyaluronic acid-methacrylate. The degradation rate, swelling performance and compressive modulus of IPN hydrogels could be adjusted by varying the degree of methacrylation of CSMA. The results of proliferation and fluorescence staining of rabbit articular chondrocytes in vitro culture demonstrated that the IPN hydrogels possessed good cytocompatibility. Furthermore, the IPN hydrogels could upregulate cartilage-specific gene expression and promote the chondrocytes secreting glycosaminoglycan and collagen II. These results suggested that IPN hydrogels might serve as promising hydrogel scaffolds for cartilage tissue engineering.

Conventional biphasic calcium phosphate (BCP) bioceramics are facing many challenges to meet the demands of regenerative medicine, and their biological properties are limited to a large extent due to the large grain size in comparison with nanocrystalline of natural bone mineral. Herein, this study aimed to fabricate porous BCP ceramic spheres with nanocrystalline (BCP-N) by combining alginate gelatinizing with microwave hybrid sintering methods and investigated their in vitro and in vivo combinational osteogenesis potential. For comparison, spherical BCP granules with microcrystalline (BCP-G) and commercially irregular BCP granules (BAM, BCP-I) were selected as control. The obtained BCP-N with specific nanotopography could well initiate and regulate in vitro biological response, such as degradation, protein adsorption, bone-like apatite formation, cell behaviors, and osteogenic differentiation. In vivo canine intramuscular implantation and rabbit mandible critical-sized bone defect repair further confirmed that nanotopography in BCP-N might be responsible for the stronger osteoinductivity and bone regenerative ability than BCP-G and BCP-I. Collectedly, due to nanotopographic similarities with nature bone apatite, BCP-N has excellent efficacy in guiding bone regeneration and holds great potential to become a potential alternative to standard bone grafts in bone defect filling applications.