Core-shell fibrous stem cell carriers incorporating osteogenic nanoparticulate cues for bone tissue engineering

Moldable hydrogels that incorporate stem cells hold great promise for tissue engineering. They secure the encapsulated cells for required periods while allowing a permeable exchange of nutrients and gas with the surroundings. Core-shell fibrous structured hydrogel system represents these properties relevant to stem cell delivery and defect-adjustable tissue engineering. A designed dual concentric nozzle is used to simultaneously deposit collagen and alginate with a core-shell structured continuous fiber form in the ionic calcium bath. We aimed to impart extrinsic osteogenic cues in the nanoparticulate form, i.e., bioactive glass nanoparticles (BGn), inside the alginate shell, while encapsulating rat mesenchymal stem cells in the collagen core. Ionic measurement in aqueous solution indicated a continuous release of calcium ions from the BGn-added and -free scaffolds, whereas silicon was only released from the BGn-containing scaffolds. The presence of BGn allowed higher number of cells to migrate into the scaffolds when implanted in subcutaneous tissues of rat. Cell viability was preserved in the presence of the BGn, with no significant differences noticed from the control. The presence of BGn enhanced the osteogenic differentiation of the encapsulated rat mesenchymal stem cells, presenting higher levels of alkaline phosphatase activity as well as bone related genes, including collagen type I, bone sialoprotein and osteocalcin. Taken together, the incorporated BGn potentiated the capacity of the core-shell fibrous hydrogel system to deliver stem cells targeting bone tissue engineering.