AggreBots: configuring CiliaBots through guided, modular tissue aggregation

Ciliated biobots, or CiliaBots, are a class of engineered multicellular
tissues that are capable of self-actuated motility propelled by the motile
cilia located on their exterior surface. Correlations have been observed
between CiliaBot motility patterns and their morphology and cilia
distribution. However, precise control of these structural parameters to
generate desired motility patterns predictably remains unexplored. Here,
we developed a novel Aggregated CiliaBot (AggreBot) platform capable of
producing designer motility patterns through spatially controlled
aggregation of epithelial spheroids made from human airway cells (referred
to as CiliaBot Building Blocks or CBBs), yielding AggreBots with
configurable geometry and distribution of active cilia. Guided multi-CBB
aggregation led to the production of rod-, triangle-, and diamond-shaped
AggreBots, which consistently effected greater motility than traditional
single-spheroid CiliaBots. Furthermore, CBBs were found to maintain
internal boundaries post-aggregation through the combined action of
pathways controlling cellular fluidity and tissue polarity. This boundary
fidelity, combined with the use of CBBs with immotile cilia due to
mutations in the CCDC39 gene, allowed for the generation of hybrid
AggreBots with precision control over the coverage and distribution of
active cilia, further empowering control of motility patterns. Our results
demonstrate the potential of AggreBots as self-propelling biological
tissues through the establishment of morphological “levers” by which
alterations to tissue motility can be theoretically planned and
experimentally verified.