Dynamic microfactories co-encapsulating osteoblastic and adipose-derived stromal cells for the biofabrication of bone units

Abstract

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.