Chitosan/collagen based biomimetic osteochondral tissue constructs: A growth factor-free approach

Gradient scaffolds for osteochondral tissue engineering and regeneration

“…Freeze-drying of porous scaffolds is based on the conversion of frozen solvents into the gas phase; this approach can fabricate scaffolds with porosity greater than 90% and median pore sizes ranging from 15 to 35 μm (with larger pores greater than 200 μm); the scaffold pores exhibit relatively high interconnectivity. This technique has been used to create OC scaffolds out of natural polymers 24 , synthetic polymers 17 , and bioactive composites [25][26][27] . The freeze-drying method uses cytotoxic solvents; as such, the scaffold needs to be washed repeatedly to remove the solvent and minimize cytotoxicity 20 .…”

“…Many types of scaffolds have been created by conventional methods such as solvent-casting 20,21 , gas-forming 22,23 , freeze-drying [24][25][26][27] , and electrospinning [28][29][30] since these approaches offer flexibility in terms of selection of biomaterials as well as control over scaffold pore size and porosity. Recently 3D printing methods have been used for the OC scaffold fabrication due to their ability to fabricate interconnected porous scaffolds with well-controlled pore geometries; the scaffold structure may be designed to exhibit appropriate mechanical properties that match the host tissue.…”

Articular cartilage and osteochondral tissue engineering techniques: Recent advances and challenges

“…The bone-cartilage interface has developed to be one of the major research projects in designing a biomimetic scaffold for osteochondral tissue engineering, and the adopted materials are always a combination of those used in chondral layer and bone layer with a specific proportion. Stratifications in the content of minerals, and porosity and pore size are common approaches [ 129 , 162 , [250] , [251] , [252] ]. ( Fig.…”

“…Nevertheless, chondrocytes are faced with several notable challenges like low isolation efficiency, limited proliferation potential and common dedifferentiation phenomenon in culture [ 18 , 292 ]. For osteochondral defect repair, chondrocytes in the cartilage layer have been used in combination with preosteoblasts in the subchondral layer to mimic the different environment in the two regions [ 251 ]. In an effort to solve the limitation of cell isolation from the non-load bearing region of articular cartilage in traditional strategy, nasal septum and auricle have been reported to be alternative cell sources of chondrocytes for articular surface reconstruction in osteochondral lesions [ [293] , [294] , [295] ].…”

“…Later studies developed the biphasic scaffolds that can simultaneously promote the regeneration of both cartilage and bone in the two individual layers without considering the intermediate calcified cartilage [ 114 , 234 ]. The importance of the interface has been taken into account in the triphasic scaffold that can better resembling the osteochondral stratification [ 112 , 251 ]. More recently, efforts have been paid to construct gradient scaffolds with gradient chemical compositions and structural characteristics, whether in multiphasic or continuous mode, which showed promising to imitate the native osteochondral tissues in a more superior way [ 256 , 280 ].…”