Bio-inspired composite and cell instructive platforms for bone regeneration

Biological studies indicate that numerous materials present in living tissues owe their success to an optimal combination of properties and adaptive structures, rather than to extreme properties per se. Through studying natural tissues and by biomimesis, new polymer and composite materials may be designed to emulate the structural and functional responses of bone. These materials must ensure biochemical affinity with host tissue through judicious mixing of specific chemical cues. Also, they must mimic the response under load exhibited by natural bone through complex organisation of material phases, i.e. embedding of collagen fibres in the extracellular substance. Fibre and particulate reinforced polymers are increasingly significant in the development of new biomedical materials, since they can be engineered more accurately than monolithic structures. Meanwhile, design of nanocomposites with specific morphological and chemical signals is emerging as a powerful approach to the mimesis of extracellular matrix of natural bone. In both cases, the manipulation of the main materials features at the micro- and nano-metric scale offers an intriguing strategy for improvement of biological and mechanical response. Several biodegradable and bioresorbable materials, as well as technologies and scaffold designs, will be critically reviewed, illustrating the potential of bio-inspired composites and multicomponent platforms for bone tissue engineering.