Levitational 3D Bioassembly and Density-Based Spatial Coding of Levitoids

摘要

Self-assembly of cells into functional bioarchitectures with microscale spatialtopographies are prevalent in nature. Despite the advances to recapitulatethe native-like microenvironment in vitro,fabrication of soft living materialswith a deterministic control on the composition, functionality, and geometry,is still challenging. Here, a versatile, paramagnetically tunable, levitationalbiofabrication technique within a ring-magnet system, RM-LEV, is developedto assemble single cells or heterogeneous multicellular living architecturesin a scaffold-free manner. The self-assembly and contactless biofabricationof multiple cell types into 3D multicellular “levitospheres” is demonstrated,where cellular positions are guided by levitation and density, simultaneously.Inherent density and diamagnetism of different cell types are leveraged tomanipulate the geometry and self-assembly of levitospheres into larger complex3D structures, termed as “levitoids”. This approach is further applied tomanipulate, position, and culture levitoids within a 3D hydrogel matrix underlevitation, which preserves their viability and functionality. Thus, this studyprovides a foundation to create spatially heterogeneous 3D cellular assemblieswith density-coded bio-architectures—which is not previously realizedusing magnetic levitation. This density-based coding approach can bebeneficial to study the cross-talk between different cell types within spheroidsand organoids, and be broadly applied to 3D bioprinting, tissue engineering,cancer, and neuroscience research.