A possible strategy in regenerative medicine is cell-sheet engineering (CSE), i.e., developing smart cell culture surfaces from which to obtain intact cell sheets (CS). The main goal of this study was to develop 3D printing via extrusion-based bioprinting of methylcellulose (MC)-based hydrogels. Hydrogels were prepared by mixing MC powder in saline solutions (Na2SO4 and PBS). MC-based hydrogels were analyzed to investigate the rheological behavior and thus optimize the printing process parameters. Cells were tested in vitro on ring-shaped printed hydrogels; bulk MC hydrogels were used for comparison. In vitro tests used murine embryonic fibroblasts (NIH/3T3) and endothelial murine cells (MS1), and the resulting cell sheets were characterized analyzing cell viability and immunofluorescence. In terms of CS preparation, 3D printing proved to be an optimal approach to obtain ring-shaped CS. Cell orientation was observed for the ring-shaped CS and was confirmed by the degree of circularity of their nuclei: cell nuclei in ring-shaped CS were more elongated than those in sheets detached from bulk hydrogels. The 3D printing process appears adequate for the preparation of cell sheets of different shapes for the regeneration of complex tissues.

Fractures of femur proximal extremity (FFPE) are the most common fragility fractures requiring hospitalization, with a high risk of mortality, low independence in the activities of daily living and severe consequences on health-related quality of life. Timing for surgery has a key role in the management of elderly patients with FFPE as recommended by the Australian and New Zealand guidelines and the National Institute for Health and Care Excellence guidelines. Early surgery (within 48 h from hospital admission) allows significant benefits in terms of lower rates of postoperative complications and risk of death and can provide better functional outcomes. Therefore, time for surgery could be considered as a comorbidity marker. The choice between conservative or surgical approach surprisingly seems to be still not strongly supported by available literature, but it seems that both 30 d and 1 year risk of mortality is higher with the conservative treatment rather than with surgery. In light of these considerations, the optimization of FFPE management care is mandatory to improve functional outcomes and to reduce sanitary costs. Albeit it is widely accepted that transdisciplinary approach to patients suffering from FFPE is mandatory to optimize both short-term and long-term outcomes, the feasibility of a comprehensive approach in clinical practice is still a challenge. In particular, the large variability of figures involved could be considered both a resource and an additional disadvantage taking into account the difficulty to coordinate multidisciplinary approach covering care in all settings. Therefore, the aim of the present article was to summarize current evidence supporting transdisciplinary management of patients with FFPE, highlighting the benefits, feasibility and limitations of this approach.

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Fibroblast growth factor-6 (FGF-6) is known to be the key ligand for fibroblast growth factor receptor 4 (FGFR4) during muscle regeneration but its role in bone has yet to be verified. FGFR signaling is known to be important in the initiation and regulation of osteogenesis, so in this study the actions of FGF-6 on human osteoblasts and osteoclasts were investigated. Human primary osteoblasts (hOB) were used to study the effect of FGF-6 on proliferation (by ATP quantification), signal transduction (by ERK and AKT phosphorylation), differentiation (by alkaline phosphatase activity, APA), and mineralization (by calcein staining). To study FGF-6 activity on osteoclast differentiation, human bone marrow cells were used and tartrate-resistant acid phosphatase (TRAP) multinucleated cells together with actin filaments arrangements were quantified. Human primary mature osteoclasts were used to evaluate the effect of FGF-6 on osteoclast reabsorbing activity by reabsorbed pit measurements. FGF-6 >10(-9) M as FGF-2 10(-7) M induced hOB proliferation mediated by pERK together with a reduction in APA and reduced mineralization of the treated cells. Moreover FGF-6 increased the formation of TRAP-positive multinucleated cells in a dose-dependent manner (maximal effect at 10(-8) M). FGF-6-treated cells showed also a greater percentage of cells that formed typical osteoclast sealing zones. Mature osteoclasts cultured on dentine slice increased the area of reabsorption with a maximal effect of FGF-6 at 10(-12) M. FGF-6 may be considered a regulator of bone metabolism as shown by its activity on both osteoblasts and osteoclasts.