Engineering anti-contractile 3D cellular assemblies using micronozzle-generated fragmented collagen microfibers

The organization of mammalian cells into three-dimensional (3D) architectures has diverse applications in tissue engineering, regenerative medicine, and <i>in vitro</i> drug screening and evaluation. Incorporation of bioactive polymer-based substrates, engineered into cell-sized materials holds significant promise in modulating the shortage of oxygen and nutrients supply, but conventional techniques face limitations in producing such small materials at high throughput. In this study, we present a facile and versatile strategy for the high-throughput production of fragmented collagen microfibers (F-CMFs) using micronozzle-assisted extrusion and stirring-induced shear forces. By carefully controlling the composition of the gelation agent solution for type-I collagen, particularly the concentrations of a polyanion and a thickener, we were able to precisely design the morphology of F-CMFs. As a practical application, we fabricated dermal tissue models using F-CMFs of varying lengths, in which F-CMFs effectively suppressed cell-driven tissue contraction. Furthermore, we demonstrated the formation of multilayered human skin tissue models comprising dermal and epidermal layers in microchannel-integrated chambers. The proposed approach offers a novel modality for creating diverse tissue models that can precisely control tissue shape and potentially enhance cellular functions through cell-matrix interactions.