The symmetry breaking of protein distribution and cytoskeleton organization is an essential aspect for the development of apicobasal polarity. In embryonic cells this process is largely cell autonomous, while differentiated epithelial cells collectively polarize during epithelium formation. Here, we demonstrate that the de novo polarization of mature hepatocytes does not require the synchronized development of apical poles on neighbouring cells. De novo polarization at the single-cell level by mere contact with the extracellular matrix and immobilized cadherin defining a polarizing axis. The creation of these single-cell liver hemi-canaliculi allows unprecedented imaging resolution and control and over the lumenogenesis process. We show that the density and localization of cadherins along the initial cell–cell contact act as key triggers of the reorganization from lateral to apical actin cortex. The minimal cues necessary to trigger the polarization of hepatocytes enable them to develop asymmetric lumens with ectopic epithelial cells originating from the kidney, breast or colon. The polarity of primary hepatocytes has now been shown to be inducible at the single-cell level by passive artificial micro-niches, indicating that the early development of polarity occurs largely independently of the types and response of the neighbouring cells.

Symmetry breaking of protein distribution and cytoskeleton organization is an essential aspect for development of apico-basal polarity. In embryonic cells this process is largely cell autonomous, while differentiated epithelial cells collectively polarize during epithelium formation. We report here that the de novo polarization of mature hepatocytes is a cell autonomous process. Single hepatocytes developed bona fide secretory hemi-apical lumens upon adhesion to finely tuned substrates bio-functionalized with cadherin and extra cellular matrix. The creation of this single cell liver allows unprecedented control and imaging resolution of the lumenogenesis process. We demonstrate that the density and localization of cadherins along the initial cell-cell contact acted as a key factor triggering the reorganization from lateral to apical actin cortex. Consequently, we established why hepatocytes could form asymmetric lumens in heterotypic doublets involving another ectopic epithelial cell originating from kidney, breast, or colon.

The in vitro methods to recapitulate environmental cues around cells are usually optimized to test a specific property of the environment (biochemical nature or the stiffness of the extracellular matrix (ECM), or nanotopography) for its capability to induce defined cell behaviors (lineage commitment, migration). Approaches that combine different environmental cues in 3D to assess the biological response of cells to the spatial organization of different biophysical and biochemical cues are growingly being developed. It is demonstrated how the lamination of through‐hole polymeric biofunctionalized membranes can be implemented to create complex bona fide microniches with differential 3D environmental properties using photoactive materials. The approach enables to create microniches ranging in size from single cells to cell aggregates. They are biofunctionalized in 3D simultaneously with topographical featured, protein patterns and structured ECM surrogate with 1 µm resolution. It is demonstrated how these niches extend in 3D the ability to pattern cells. It is exemplified how they can be used to standardize cells' shapes in 3D and to trigger the apicobasal polarization of single epithelial cells.

We present here a method to create arrays of microcavities that can be differentially coated on their bottom, side, and top with different proteins. These cavities range in size from single cell to multicellular aggregate. We provide detailed protocols to create such arrays with some variations using different materials and different coating proteins. The use of such cavities as bona fide artificial microniches to mimic cellular microenvironments has been already established and is referenced.

We model the dynamics of formation of intercellular secretory lumens. Using conservation laws, we quantitatively study the balance between paracellular leaks and the build-up of osmotic pressure in the lumen. Our model predicts a critical pumping threshold to expand stable lumens. Consistently with experimental observations in bile canaliculi, the model also describes a transition between a monotonous and oscillatory regime during luminogenesis as a function of ion and water transport parameters. We finally discuss the possible importance of regulation of paracellular leaks in intercellular tubulogenesis.

Ultrathin through-hole membranes with spatially ordered and monodisperse nanopores are attracting growing interests in academic studies and industrial applications. Herein, by adapting capillary driven mold-based patterning techniques, the authors present, a facile, benchtop method for the fabrication of such membranes without elaborate post-etching steps and costly instrumentations, which remain the intrinsic fabrication limitations in existing methods. The theory and experiment on the capillary driven imprint depth and timescale are in good agreement, thus providing predictive design guidelines to accurately control lateral (size, shape) and vertical (depth) dimensions of membrane pore features, using a singular master mold template. Another pressing limitation resides in the thin membrane's difficult detachment from the substrate after patterning. The membrane implementation bottleneck is resolved by a versatile sacrificial layer mediated transfer method that not only facilitates high fidelity transfer of ultrathin membranes onto various target substrates but also enable the assembly of membranes with ideal hierarchical layer structure in which each hierarchy has ordered pore morphology and distinct function. The fabrication approach described herein paves the way for a myriad of greater membrane functions not easily achieved through conventional membranes; especially in filtration, biology, and environmental applications that require exceptional size selectivity and unhindered flow pathways.

Biomimetic materials have long been the (he) art of bioengineering. They usually aim at mimicking in vivo conditions to allow in vitro culture, differentiation and expansion of cells. The past decade has witnessed a considerable amount of progress in soft lithography, bioinspired micro-fabrication and biochemistry, allowing the design of sophisticated and physiologically relevant micro-and nanoenvironments. These systems now provide an exquisite toolbox with which we can control a large set of physicochemical environmental parameters that determine cell behavior. Biofunctionalized surfaces have evolved from simple protein-coated solid surfaces or cellular extracts into nano-textured 3D surfaces with controlled rheological and topographical properties. The mechanobiological molecular processes by which cells interact and sense their environment can now be unambiguously understood down to the single-molecule level. This Commentary highlights recent successful examples where bio-functionalized substrates have contributed in raising and answering new questions in the area of extracellular matrix sensing by cells, cell-cell adhesion and cell migration. The use, the availability, the impact and the challenges of such approaches in the field of biology are discussed.

By culturing rat hepatocyte doublets in microwells with controlled ECM environments, Viasnoff and colleagues show that the lumen between the cells extends anisotropically towards regions of lower intercellular tension.