Microtissue self‐assembly is thought to be driven primarily by cadherins, while connexons have been examined mainly in intercellular coupling. We investigated whether connexon 43 (Cx43)‐mediated cell adhesion modulates self‐assembly of human KGN granulosa cells, normal human fibroblasts (NHFs), and MCF‐7 breast cancer cells seeded into nonadhesive agarose gels. We found that treatment with anti‐Cx43 E2 (112 µg/ml), which suppresses Cx43 docking, significantly inhibited the kinetics of KGN and NHF self‐assembly compared to the preimmune sera control (41.1±4.5 and 24.5±10.4% at 8 h, respectively). Likewise, gap junction inhibitor carbenoxolone also inhibited self‐assembly of KGN, NHF, and MCF‐7 cells in a dose‐dependent manner that was specific to cell type. In contrast, Gap26 connexin mimetic peptide, which inhibits channel permeability but not docking, accelerated self‐assembly of KGN and NHF microtissues. Experiments using selective enzymatic digestion of cell adhesion molecules and neutralizing N‐cadherin antibodies further showed that self‐assembly was comparably disrupted by inhibiting connexin‐ and cadherin‐mediated adhesion. These findings demonstrate that connexon‐mediated cell adhesion and intercellular communication differentially influence microtissue self‐assembly, and that their contributions are comparable to those of cadherins.—Bao, B., Jiang, J., Yanase, T., Nishi, Y., Morgan, J. R. Connexon‐mediated cell adhesion drives microtissue self‐assembly. FASEBJ. 25, 255–264 (2011). http://www.fasebj.org

Background: Panx1 is a novel gap junction protein with tumor-suppressive properties. Results: Panx1 channels release ATP to initiate a cascade that drives actomyosin-mediated assembly of multicellular aggregates. Conclusion: Expression of Panx1 can directly alter the biomechanical properties of three-dimensional tumor aggregates. Significance: Panx1 channels through P 2 X 7 signaling help regulate three-dimensional biomechanics of tumor suppression.

A significant challenge to the field of biofabrication is the rapid construction of large three dimensional (3D) living tissues and organs. Multi-cellular spheroids have been used as building blocks. In this paper, we create large multi-cellular honeycomb building blocks using directed self-assembly, whereby cell-to-cell adhesion, in the context of the shape and obstacles of a micromold, drives the formation of a 3D structure. Computer aided design, rapid prototyping and replica molding were used to fabricate honeycomb-shaped micro-molds. Nonadhesive hydrogels cast from these micro-molds were equilibrated in cell culture medium and seeded with two types of mammalian cells. The cells settled into the honeycomb recess, were unable to attach to the nonadhesive hydrogel and so cell-to-cell adhesion drove the self-assembly of a large multicellular honeycomb within 24 hours. Distinct morphological changes occurred to the honeycomb and its cells indicating the presence of significant cell-mediated tension. Unlike the spheroid, whose size is constrained by a critical diffusion distance needed to maintain cell viability, the overall size of the honeycomb is not limited. The rapid production of the honeycomb building unit, with its multiple rings of high density cells and open lumen spaces, offers interesting new possibilities for biofabrication strategies.