Acidic peptide hydrogel scaffolds enhance calcium phosphate mineral turnover into bone tissue.

Designed peptides may generate molecular scaffolds in the form of hydrogels to support tissue regeneration. We studied the effect of hydrogels comprising β-sheet-forming peptides rich in aspartic amino acids and of tricalcium phosphate (β-TCP)-loaded hydrogels on calcium adsorption and cell culture in vitro, and on bone regeneration in vivo. The hydrogels were found to act as efficient depots for calcium ions, and to induce osteoblast differentiation in vitro. In vivo studies on bone defect healing in rat distal femurs analyzed by microcomputerized tomography showed that the peptide hydrogel itself induced better bone regeneration in comparison to non-treated defects. A stronger regeneration capacity was obtained in bone defects treated with β-TCP-loaded hydrogels, indicating that the peptide hydrogels and the mineral act synergistically to enhance bone regeneration. In vivo regeneration was found to be better with hydrogels loaded with porous β-TCP than with hydrogels loaded with non-porous mineral. It is concluded that biocompatible and biodegradable matrices, rich in anionic moieties that efficiently adsorb calcium ions while supporting cellular osteogenic activity, may efficiently promote β-TCP turnover into bone mineral.