Incorporation of the natural marine multi-mineral dietary supplement Aquamin enhances osteogenesis and improves the mechanical properties of a collagen-based bone graft substitute.

Aquamin is a commercially-available supplement derived from the algae species Lithothamnion, which has proven osteogenic potential. By harnessing this potential and combining Aquamin with a collagen scaffold, with architecture and composition optimised for bone repair, the aim of this study was to develop a natural osteo-stimulative bone graft substitute. A fabrication process was developed to incorporate Aquamin into scaffolds to produce collagen-Aquamin (CollAqua) scaffolds at two different Aquamin concentrations, 100F or 500F (equivalent weight% of collagen or five times the weight of collagen respectively). CollAqua constructs had improved mechanical properties which were achieved without reducing the scaffold׳s permeability or porosity below the minimum level required for successful bone tissue engineering. The fabrication process produced a homogenous Aquamin distribution throughout the scaffold. Release kinetics revealed that in the first 12h, the entire Aquamin content was released from the 100F however, less than half of Aquamin in the 500F was released with the remainder released approximately 21 days later giving an initial burst release followed by a delayed release. Osteoblasts cultured on the CollAqua scaffolds showed improved osteogenesis as measured by alkaline phosphatase, osteopontin and osteocalcin expression. This was confirmed by increased mineralisation as determined by von Kossa and Alizarin red staining. In conclusion, a cell and growth factor free collagen-based bone graft substitute with enhanced mechanical properties has been developed. The addition of Aquamin to the collagen biomaterial significantly improved mineralisation by osteoblasts and results in a new product which may be capable of enhancing osteogenesis to facilitate bone repair in vivo.