Osteoporosis is a worldwide disease with a high prevalence in elderly population; it results in bone loss and decreased bone strength that lead to low-energy fractures. Since antiresorptive treatments could lead to long-term adverse effects, the ERC BOOST project aims to propose a biomimetic 3D-printed scaffold reproducing the architecture and chemistry of healthy bone. In this study, the structural parameters of healthy bone were studied in order to reproduce them through 3D printing; furthermore, structural and mechanical differences between healthy and osteoporotic (OP) bones were assessed. Healthy and OP humeral heads discarded during surgical interventions (following ethical approval by Istituto Ortopedico Rizzoli-Italy) were tomographically analysed to obtain bone structural parameters. Successively, 8 mm diameter biopsies were harvested from the heads and underwent compression and nanoindentation tests to investigate macroscopic and microscopic mechanical properties, respectively. XRD measurements were performed on bone fragments. OP bone samples exhibited inferior mechanical properties to their less interconnected and more anisotropic structure, with thinner trabeculae and larger pores. On the other hand, nanoindentations performed on OP trabeculae showed increased Young Modulus compared to healthy samples probably due to their increased hydroxyapatite crystal size, as revealed by XRD. Osteoporosis causes the weakening of the trabecular structure that leads to a decrease of bone mechanical properties. However, OP trabeculae are stiffer due to increased dimensions of hydroxyapatite crystals.

Osteoporosis is a worldwide spread, silent disease steadily increasing due to demographic shift; it results in bone loss and increased porosity that lead to an increase in bone fragility and to low-energy fractures. In such a contest, we worked on the development of 3D scaffolds engineered to mimic the features of human healthy bone. Healthy and osteoporotic bone microCT scans were obtained from tissues discarded during surgical interventions (Istituto Ortopedico Rizzoli-Italy). The obtained .STL file was used to 3D print a type I collagen solution to mimic bone matrix whereas mesoporous bioactive glass/nano-hydroxyapatite were embedded within the collagen fibers to mimic the inorganic phase of human bone. The rheological properties of the Type I collagen/mesoporous glass suspensions were investigated at different collagen concentration and temperatures. The possibility of incorporating growth factors (IGF and β-TGF) in the scaffold struts was investigated proposing several approaches and their retained activity was assessed. Different co-culture of osteoblasts and osteoclasts set-ups were explored in order to define the influence of both chemical and topographical stimuli on the osteoblast-osteoclast coupling.