A grand challenge of tissue engineering is the fabrication of large constructs with a high density of living cells. By adapting the principles of pick-and-place machines used in the high-speed assembly of electronics, we have developed an innovative instrument, the Bio-Pick, Place, and Perfuse (Bio-P3), which picks up large complex multicellular building parts, transports them to a build area, and precisely places the parts at desired locations while perfusing the parts. These assembled parts subsequently fuse to form a larger contiguous tissue construct. Multicellular microtissues were formed by seeding cells into nonadhesive micro-molds, wherein cells self-assembled scaffold-free parts in the shape of spheroids, toroids, and honeycombs. After removal from the molds, the parts were gripped, transported (using an x, y, z controller), and released using the Bio-P3 with little to no effect on cell viability or part structure. As many as 16 toroids were stacked over a 170 μm diameter post where they fused over the course of 48 h to form a single tissue. Larger honeycomb parts were also gripped and stacked onto a build head that, like the gripper head, provided fluid suction to hold and perfuse the parts during assembly. Scaffold-free building parts help to address several of the engineering and biological challenges to large tissue biofabrication, and the Bio-P3 described in this article is a novel instrument for the controlled gripping, placing, stacking, and perfusing of living building parts for solid organ fabrication.

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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.