Collagen/alginate scaffolds comprising core (PCL)-shell (collagen/alginate) struts for hard tissue regeneration: Fabrication, characterisation, and cellular activities

We herein describe a novel hybrid scaffold comprising microsized struts with a core (PCL)-shell (collagen/alginate) structure. The collagen-based hybrid scaffold was fabricated using cryogenic plotting/melt-plotting methods supplemented with a core-shell nozzle. The core region (PCL) in the struts has mechanical support and shape integrity functions, and the shell region (collagen/alginate) enhances biological activities. Through use of various processing conditions, we could manipulate the mechanical properties of the scaffolds without any loss of biological functions, similar to a pure collagen scaffold. The mechanical properties of the hybrid scaffold were enhanced by ∼12-fold compared with those of a pure collagen scaffold due to the reinforcement of the core region (PCL). To demonstrate the feasibility as a hard-tissue scaffold, osteoblast-like cells (MG63) were seeded and the cell-seeding efficiency and various cellular activities were investigated. The cell-seeding efficiency (53%) and cell viability of the hybrid scaffold were similar to those of the pure collagen scaffold (57%), while the pure PCL scaffold showed relatively low cell-seeding efficiency (19%) and viability. To determine its potential as a scaffold for bone tissue regeneration, in vitro cellular activities, including ALP activity and calcium deposition, were compared with those of the pure collagen scaffold; no statistically significant differences compared with those of the pure collagen scaffold were found. These results indicate that the in vitro cellular activities of the hybrid scaffolds were identical to those of the pure collagen scaffold; moreover, the hybrid scaffold exhibited significantly improved mechanical properties.