Engineering 3D cell instructive microenvironments by rational assembly of artificial extracellular matrices and cell patterning.

Engineered artificial microenvironments hold enormous potential as models to study developmental, physiological, pathological, and regenerative processes under highly defined conditions. Such platforms aim at bridging the gap between traditional in vitro 2D culture systems and animal models. By dissecting the biological complexity into an amenable number of parameters, systemic manipulation and study in controllable environments closely resembling the in vivo situation is possible. Novel strategies that address the evaluation of either ECM components, growth factors or cell-cell interactions on cellular behaviour are being developed. However, reliable methods that simultaneously recapitulate the natural instructive microenvironments in terms of cell and matrix composition, biological cues, heterogeneity and geometry are not yet available. Such spatially-defined microenvironments may be necessary to initiate and guide the formation of artificial tissues by morphogenetic processes. In this work, we introduce a flexible strategy that relies on the combination of artificial extracellular matrices with patterning techniques as well as a layer-by-layer approach to mimic rationally-designed instructive milieus. By a rational arrangement of cells and defined biochemical and biophysical extracellular cues, we report control of cell migration and generation of an artificial vascularized bone tissue-like construct.