Coral Scaffolds in Bone Tissue Engineering and Bone Regeneration

Abstract

Coral exoskeleton, which consists of CaCO3 and has an interconnected-pore structure that resembles that of natural human bone, has been used as scaffold material to fill bone defects in both animal models and humans since the early 1970s. This natural material is biocompatible, osteoconductive, and biodegradable. Most importantly, the possibility of seeding coral scaffolds with either stem cells or loading them with growth factors has provided novel alternatives for bone tissue engineering. In vitro studies have demonstrated that (1) seeded cells adhered and proliferated in a time-dependent manner, and (2) loaded growth factors were absorbed on coral scaffold and subsequently released. Moreover, when coral scaffolds containing either cells and/or growth factors were implanted in vivo, a significantly increased amount of newly-formed bone was observed. Most importantly, timely resorption of the scaffold material in vivo was associated with full bone regeneration in a clinically-relevant sheep model of bone defect. Although sometimes inconsistent, such outcomes provided evidence that bone regeneration, which matches, and even supersedes, the efficacy of autologous bone graft, is achievable with coral scaffolds.