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BACKGROUND Calcium ions levels in bone niches have been demonstrated to severely influence new bone formation. Osteoinductive scaffolds containing calcium have been largely studied to control the release of calcium in bone regeneration and tissue engineering purpose. The aim of the present study was, firstly, to synthesize two different resorbable calcium phosphate-based powders, thought to be reservoirs of calcium ions, and secondary, to investigate their effects on human osteoblasts, in order to develop a suitable titanium coating material. METHODS Tetracalcium phosphate (A450) and biphasic tetracalcium phosphatae/tricalcium phosphate (A850) powders were prepared with an innovative method. The presence of calcium phosphate structures was chemically confirmed with XRD. Furthermore, powders macroscopic aspect was observed with a stereomicroscope. For in-vitro experiments, human osteoblastic cells were cultured in the presence of A450 and A850, and assayed for viability and metabolic activity through Crystal Violet and MTT, respectively. RESULTS Our synthesis led to the formation of calcium phosphates in both samples, even though A850 presented a higher level of crystallinity and a more powdery aspects than A450. Both the samples enhanced the viability of cultured cells, inhibiting cell metabolic activity in the case of A850, which furthermore showed to be internalized by cells. CONCLUSIONS We developed two different kind of calcium phosphate-based powders and we tested their effect on human osteoblasts, underlying the possibility of use calcium phosphate-based coatings to enhance cell response on implantable materials.

La ricerca di nuove strategie per la rigenerazione ossea rappresenta un focus di interesse centrale per migliorare la gestione di casi clinici complessi nell’ambito della chirurgia orale e maxillo-facciale. Uno degli approcci più utilizzati in tale contesto si basa sull’utilizzo di molecole con proprietà osteoinduttive e molte sostanze sono state fino ad oggi sperimentate. E’ noto in letteratura che gli androgeni svolgono un ruolo chiave nella regolazione della morfogenesi ossea e nel mantenimento della sua omeostasi durante il corso della vita. Questo lavoro di tesi nasce dall’ipotesi che la somministrazione locale di tali ormoni, eventualmente combinata a materiali da innesto, possa favorire la guarigione di difetti ossei. Stando a questa premessa, sono stati valutati gli effetti dello steroide sintetico Stanozololo sulla rigenerazione ossea in diversi settings sperimentali. La tesi è strutturata secondo un percorso che segue le fasi della ricerca, attraverso sperimentazioni in vitro e in vivo; ogni capitolo può essere approcciato come uno studio a sé stante, corrispondente ad una determinata tappa dell’iter sperimentale. Sulla base di questi intenti, viene fornito inizialmente un quadro d’insieme circa gli effetti degli androgeni sull’osso. A seguire, è presentata una sperimentazione in vitro nella linea cellulare SaOS-2. Infine, è proposta un’innovativa metodologia di analisi per lo studio della rigenerazione ossea nel modello di ratto, ove viene testata la somministrazione locale di Stanozololo combinato a materiale da innesto. The study of new strategies for bone regeneration represents the main goal to improve the management of demanding clinical situations in oral and maxillofacial surgery. In such a context, the combination of osteoinductive molecules with grafting biomaterials is a field of growing interest and many agents have been tested so far. It is widely known that sex steroid hormones play a significant role in regulating morphogenesis and in maintaining homeostasis of bone throughout life. This thesis work arises from the hypothesis local androgen administration, possibly in combination with grafting materials, may favor the healing of bone defects. Following this idea, the effects of the synthetic androgen Stanozolol on bone regeneration have been evaluated in different experimental settings. The present work is structured along a pathway which goes from in vitro to in vivo investigations; each chapter can be approached as an independent study, which corresponds to a distinct experimental phase. Based on this idea, an overview about androgen effects on bone, is initially provided. Then, and the subsequent in vitro investigation SaOS-2 cell line is described. Lastly, an innovative analysis methodology to study bone regeneration in a rat- model is proposed and local Stanozolol administration combined to a grafting biomaterial is tested in bone defects.