Funnel-Guided Positioning of Multicellular Microtissues to Build Macrotissues.

The field of tissue engineering is developing new additive manufacturing technologies to fabricate 3D living constructs for use as in vitro platforms for the testing of drugs and chemicals, or to restore lost function in vivo. In this article, we describe the funnel-guide (FG), a new additive manufacturing strategy for the noncontact manipulation and positioning of multicellular microtissues and we show that the FG can be used to build macrotissues layer by layer. We used agarose micromolds to self-assemble cells into toroid-shaped and honeycomb-shaped microtissues, and observed that when falling in cell culture medium, the microtissues spontaneously righted themselves to a horizontal orientation. We fabricated a funnel to guide these falling toroids and honeycombs into precise positions and stack them, wherein they fused to form tubular structures. We tested multiple cell types and toroid sizes, and ultimately used the FG to create a stack of 45 toroids that fused into a tube 5 mm long with an inner diameter of 600 µm. The FG is a new principle for the manipulation of microtissues and is a platform for the layer-by-layer positioning of microtissue building blocks to form macrotissues.