Material extrusion (MEX), commonly referred to as fused deposition modeling (FDM) or fused filament fabrication (FFF), is a versatile and cost-effective technique to fabricate suitable scaffolds for tissue engineering. Driven by a computer-aided design input, specific patterns can be easily collected in an extremely reproducible and repeatable process. Referring to possible skeletal affections, 3D-printed scaffolds can support tissue regeneration of large bone defects with complex geometries, an open major clinical challenge. In this study, polylactic acid scaffolds were printed resembling trabecular bone microarchitecture in order to deal with morphologically biomimetic features to potentially enhance the biological outcome. Three models with different pore sizes (i.e., 500, 600, and 700 µm) were prepared and evaluated by means of micro-computed tomography. The biological assessment was carried out seeding SAOS-2 cells, a bone-like cell model, on the scaffolds, which showed excellent biocompatibility, bioactivity, and osteoinductivity. The model with larger pores, characterized by improved osteoconductive properties and protein adsorption rate, was further investigated as a potential platform for bone-tissue engineering, evaluating the paracrine activity of human mesenchymal stem cells. The reported findings demonstrate that the designed microarchitecture, better mimicking the natural bone extracellular matrix, favors a greater bioactivity and can be thus regarded as an interesting option for bone-tissue engineering.

Exposure to high levels of radiation can cause acute, long-term health effects, such as acute radiation syndrome, cancer, and cardiovascular disease. This is an important occupational hazard in different fields, such as the aerospace and healthcare industry, as well as a crucial burden to overcome to boost space applications and exploration. Protective bulky equipment made of heavy metals is not suitable for many advanced purporses, such as mobile devices, wearable shields, and manned spacecrafts. In the latter case, the in-space manufacturing of protective shields is highly desirable and remains an unmet need. Composites made of polymers and high atomic number fillers are potential means for radiation protection due to their low weight, good flexibility, and good processability. In the present work, we developed electrospun composites based on polycaprolactone (polymer matrix) and tungsten powder for application as shielding materials. Electrospinning is a versatile technology that is easily scalable at an industrial level and allows obtaining very lightweight, flexible sheet materials for wearables. By controlling tungsten powder size, we engineered homogeneous, stable and processable suspensions to fabricate radiation composite shielding sheets. The shielding capability was assessed by an in vivo model on prototype composite sheets containing 80 w% of W filler in a polycaprolactone (PCL) fibrous matrix by means of irradiation tests (X-rays) on mice. The obtained results are promising; as expected, the shielding effectivity of the developed composite material increases with the thickness/number of stacked layers. It is worth noting that a thin barrier consisting of 24 layers of the innovative shielding material reduces the extent of apoptosis by 1.5 times compared to the non-shielded mice.

Three-dimensional cell culture systems are relevant in vitro models for studying cellular behavior. In this regard, this present study investigates the interaction between human osteoblast-like cells and 3D-printed scaffolds mimicking physiological and osteoporotic bone structures under simulated microgravity conditions. The objective is to assess the effects of scaffold architecture and dynamic culture conditions on cell adhesion, proliferation, and metabolic activity, with implications for osteoporosis research. Polylactic acid scaffolds with physiological (P) and osteoporotic-like (O) trabecular architectures were 3D-printed by means of fused deposition modeling technology. Morphometric characterization was performed using micro-computed tomography. Human osteoblast-like SAOS-2 and U2OS cells were cultured on the scaffolds under static and dynamic simulated microgravity conditions using a rotary cell culture system (RCCS). Scaffold biocompatibility, cell viability, adhesion, and metabolic activity were evaluated through Bromodeoxyuridine incorporation assays, a water-soluble tetrazolium salt assay, and an enzyme-linked immunosorbent assay of tumor necrosis factor-α secretion. Both scaffold models supported osteoblast-like cell adhesion and growth, with an approximately threefold increase in colonization observed on the high-porosity O scaffolds under dynamic conditions. The dynamic environment facilitated increased surface interaction, amplifying the effects of scaffold architecture on cell behavior. Overall, sustained cell growth and metabolic activity, together with the absence of detectable inflammatory responses, confirmed the biocompatibility of the system. Scaffold microstructure and dynamic culture conditions significantly influence osteoblast-like cell behavior. The combination of 3D-printed scaffolds and a RCCS bioreactor provides a promising platform for studying bone remodeling in osteoporosis and microgravity-induced bone loss. These findings may contribute to the development of advanced in vitro models for biomedical research and potential countermeasures for bone degeneration.

Background/Objectives: Three-dimensional cell culture systems are relevant in vitro models for studying cellular behavior. In this regard, the present study investigates the interaction between human osteoblast-like cells and 3D-printed scaffolds mimicking physiological and osteoporotic bone structures under simulated microgravity conditions. The objective is to assess the effects of scaffold architecture and dynamic culture conditions on cell adhesion, proliferation, and meta-bolic activity, with implications for both osteoporosis research and space medicine. Methods: Poly (lactic acid) (PLA) scaffolds with physiological (P) and osteoporotic-like (O) tra-becular architectures were 3D printed by means of the used deposition modeling (FDM) tech-nology. Morphometric characterization was performed using micro-computed tomography (µCT). Human osteoblast-like SAOS-2 and U2OS cells were cultured on the scaffolds under static and dynamic simulated microgravity conditions using a rotary cell culture system (RCCS). Cell viability, adhesion, and metabolic activity were evaluated through BrdU, WST-1, and ELISA assays, with TNF-α secretion assessed to determine biocompatibility. Results: Both scaffold models supported osteoblast-like cell adhesion and growth, with enhanced colonization observed on the high-porosity O scaffolds under dynamic conditions. The dynamic environment facilitated increased surface interaction, amplifying the effects of scaffold archi-tecture on cell behavior. No inflammatory response was detected, confirming scaffold biocom-patibility.