Bioactive and porous-structured nanocomposite microspheres effective for cell delivery: a feasibility study for bone tissue engineering

Abstract

A novel nanocomposite microspherical cell-carrier system was developed to populate stem cells and to stimulate their osteogenesis for bone tissue engineering. A biopolymer-based composition incorporating bioactive glass nanoparticles (BGn) was spherodized with a size of hundreds of micrometers. In particular, the morphology of the microcarriers was porous-structured with the help of camphene. The nanocomposite porous microcarriers showed excellent surface bioactivity, easily forming apatite mineral in vitro. Rat mesenchymal stem cells populated well onto the porous microcarriers, exhibiting tight anchorage with the underlying surface and active spreading and proliferation behaviors. The surface-mineralization significantly improved the cell proliferative potential. In vivo tests in rat calvarial defects confirmed the excellent tissue compatibility of the microcarriers. The BGn incorporation and the surface mineralization significantly improved the ingrowth of cells and tissues within the pore channels and the consequent bone regeneration. In particular, the mineralized surface showed enhanced capacity to deliver protein molecules, loading at higher quantity and releasing them more slowly than the unmineralized surface. The results demonstrated the feasibility of the nanocomposite porous microspheres as a potential cell delivery system for bone tissue engineering.