Cells with differentiation potential into mesodermal types are the focus of emerging bone tissue engineering (TE) strategies as an alternative autologous source. When the source of cells is extremely limited or not readily accessible, such as in severe injuries, a tissue biopsy may not yield the required number of viable cells. In line, adipose-derived stromal cells (ASCs) quickly became attractive for bone TE, since they can be easily and repeatably harvested using minimally invasive techniques with low morbidity. Inspired by the multiphenotypic cellular environment of bone, we propose the co-encapsulation of ASCs and osteoblasts (OBs) in self-regulated liquefied and multilayered microcapsules. We explore the unique architecture of such hybrid units to provide a dynamic environment using a simple culture in spinner flasks. Results show that microtissues were successfully obtained inside the proposed microcapsules with an appropriate diffusion of essential molecules for cell survival and signaling. Remarkably, microcapsules cultured in the absence of supplemental osteogenic differentiation factors presented osteopontin immunofluorescence, evidencing that the combined effect of the dynamic environment, and the paracrine signaling between ASCs and OBs may prompt the development of bone-like microtissues. Furthermore, microcapsules cultured under dynamic environment presented an enhanced mineralized matrix and a more organized extracellular matrix ultrastructure compared to static cultures used as control. Altogether, data in this study unveil an effective engineered bioencapsulation strategy for the in vitro production of bone-like microtissues in a more realistic and cost-effective manner. Accordingly, we intend to use the proposed system as hybrid devices implantable by minimally invasive procedures for bone TE applications.

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Embedded bio-printing has fostered significant advances toward the fabrication of soft complex tissue-like constructs, by providing a physical support that allows the freeform shape maintenance within the prescribed spatial arrangement, even under gravity force. Current supporting materials still present major drawbacks for up-scaling embedded 3D bio-printing technology towards tissue-like constructs with clinically relevant dimensions. Herein, we report a a cost-effective and widely available supporting material for embedded bio-printing consisting on a continuous pseudo-plastic matrix of xanthan-gum (XG). This natural polisaccharide exhibits peculiar rheological properties that have enabled the rapid generation of complex volumetric 3D constructs with out-of-plane features. The freedom of design within the three orthogonal axes through the independent and controlled bio-printing process opens new opportunities to produce on demand large arbitrary shapes for personalized medicine. Additionally, we have demonstrated the versatile functionality of XG as a photocurable gel reservoir to engineer perfused cell-laden hydrogel constructs, addressing other practical biomedical applications such as in vitro models and organ-on-chip platforms.