Polymer based scaffolds for tissue regeneration

To attain a successful ECM analogue scaffold, there are several design and material criteria that must be satisfied involving the mimicking of topographical features and geometry on the macro-, micro- and even at nanoscale levels, because each influences cell response to the scaffold. In the last years, a successful approach has been represented by the use of composite scaffolds obtained by a combination of phase inversion, salt leaching, filament winding technology. These techniques enable obtaining porous scaffold with controlled micro and macro porosity able to influence positively mechanical properties and cell interactions. In particular, composite materials based on biodegradable polymers (i.e. poly-ε-caprolactone) endowed with intrinsically bioactive particles (i.e. calcium phosphates) and/or macromolecules (i.e Hyaluronic Acid), offers the possibility to realize a strong bond with natural tissues through more bioactive, structurally and mechanically efficient interfaces, firstly enhancing the capability of the substrate to form new extracellular matrix (ECM) and assuring a more rapid and efficacious integration to the implant site. However, some limitations of traditional process impose to identify innovative strategies for fabricating micro and nanostructures structures. In this context, interesting approaches based on the assembly of basic components or building blocks endowed with molecular signals are powerfully emerging to form hierarchically complex structures, able to accurately recapitulate the functional properties of natural complex structures. For connective tissue regeneration (bone, ligaments, meniscus) compo-site scaffolds are obtained by phase inversion, salt leaching and RP technique to modulate mechanical properties and cell interactions. Design of bioactive scaffolds for bone regeneration with appropriate porosity and high pores interconnectivity could be obtained by using Poly(ε-caprolactone) reinforced with Calcium Phosphates particles and PLA fibres. Ester of Hyaluronic Acid reinforced with degradable fibres were processed by composite technology, phase inversion and salt leaching technique to obtain scaffolds for meniscus regeneration. In vivo results demonstrated the possibility to regenerate the meniscus by using an appropriate scaffolds. Imaging and rapid prototyping technologies are implemented to design a “custom made” meniscus scaffold. A critical discussion on the advantages of new approaches has been performed by proposing strategies based on composite to the assembly of elementary components such as fibres implemented through modified electrospinning or sintering techniques