Biosynthesis of injectable gelling peptides for applications in bone tissue regeneration.

Tissue engineering and regenerative medicine are part of an emerging and interdisciplinary field that applies the principles of engineering and life sciences towards the development of biological substitutes. This innovative strategy may help identify suitable alternatives to current clinical treatments for a variety of pathologies, such as bone injuries and diseases, whose growing incidence is increasing the demand of medical and healthcare resources. Peptide hydrogels may be used in this context as biocompatible and biodegradable materials suitable for cell encapsulation and for the controlled spatial and temporal delivery of biomolecules (e.g. growth factors) able to direct cell differentiation. Recently, we developed an enzymatic approach for the preparation of injectable, self-assembling materials based on Fmoc-oligopeptides1. The reaction products spontaneously self-assemble in water to form a 3D structure of entangled nanofibers. These materials can be used as controlled drug delivery systems for bioactive molecules2 and may enhance cell production of growth factors3. We employed such hydrogels for the preparation of composite materials specifically designed for bone tissue regeneration. These tailor-made hydrogel systems contain biopolymeric spheres delivering bioactive molecules, as well as pure and substituted calcium phosphate (CaP) nanoparticles to provide bioactivity, osteoconductivity and improved mechanical properties. Ongoing work is aimed at investigating the biological properties of the composite hydrogel systems, in terms of adhesion, growth and differentiation of human mesenchymal stem cells.