Vitalisation of tubular coral scaffolds with cell sheets for regeneration of long bones: a preliminary study in nude mice

In this study, cell sheets comprising multilayered living bone marrow stromal cells and extracellular matrix were assembled with tubular coral scaffolds for long bone regeneration. Cell sheet with visible mineralized nodules was harvested and wrapped against tubular coral scaffolds with 5 mm diameter and 1.5 mm wall thickness. New bone formation was investigated by CT scan and histological observation 8 and 12 weeks after implantation of cell sheet/scaffold. The results showed that cortical bone formed within the constructs for both groups. New bone composed 25.75% of the graft in 8 weeks group, compared to that of 40.01% in 12 weeks group. Histological examination showed that new bone formation was in the manner of endochondral osteogenesis, with woven bone matrix subsequently maturing into fully mineralized compact bone. These findings demonstrated that osteogenic cell sheet could vitalize tubulate coral scaffolds to regenerate bone graft with similar shape and structure to native bone.