Author Correction: Investigating the nature of active forces in tissues reveals how contractile cells can form extensile monolayers

Supramolecular Hydrogel with Ultra-Rapid Cell-Mediated Network Adaptation for Enhancing Cellular Metabolic Energetics and Tissue Regeneration

Cellular energetics plays an important role in tissue regeneration, and the enhanced metabolic activity of delivered stem cells can accelerate tissue repair and regeneration. However, conventional hydrogels with limited network cell adaptability restrict cell-cell interactions and cell metabolic activities. In this work, it is shown that a cell-adaptable hydrogel with high network dynamics enhances the glucose uptake and fatty acid β-oxidation of encapsulated human mesenchymal stem cells (hMSCs) compared with a hydrogel with low network dynamics. It is further shown that the hMSCs encapsulated in the high dynamic hydrogels exhibit increased tricarboxylic acid (TCA) cycle activity, oxidative phosphorylation (OXPHOS), and adenosine triphosphate (ATP) biosynthesis via an E-cadherin- and AMP-activated protein kinase (AMPK)-dependent mechanism. The in vivo evaluation further showed that the delivery of MSCs by the dynamic hydrogel enhanced in situ bone regeneration in an animal model. It is believed that the findings provide critical insights into the impact of stem cell-biomaterial interactions on cellular metabolic energetics and the underlying mechanisms.

Mechanical basis and topological routes to cell elimination

Cell layers eliminate unwanted cells through the extrusion process, which underlines healthy versus flawed tissue behaviors. Although several biochemical pathways have been identified, the underlying mechanical basis including the forces involved in cellular extrusion remains largely unexplored. Utilizing a phase-field model of a three-dimensional cell layer, we study the interplay of cell extrusion with cell-cell and cell-substrate interactions in a flat monolayer. Independent tuning of cell-cell versus cell-substrate adhesion forces reveals that extrusion events can be distinctly linked to defects in nematic and hexatic orders associated with cellular arrangements. Specifically, we show that by increasing relative cell-cell adhesion forces the cell monolayer can switch between the collective tendency towards fivefold, hexatic, disclinations relative to half-integer, nematic, defects for extruding a cell. We unify our findings by accessing three-dimensional mechanical stress fields to show that an extrusion event acts as a mechanism to relieve localized stress concentration.

Tuning Epithelial Cell-Cell Adhesion and Collective Dynamics with Functional DNA-E-Cadherin Hybrid Linkers

The binding strength between epithelial cells is crucial for tissue integrity, signal transduction and collective cell dynamics. However, there is no experimental approach to precisely modulate cell-cell adhesion strength at the cellular and molecular level. Here, we establish DNA nanotechnology as a tool to control cell-cell adhesion of epithelial cells. We designed a DNA-E-cadherin hybrid system consisting of complementary DNA strands covalently bound to a truncated E-cadherin with a modified extracellular domain. DNA sequence design allows to tune the DNA-E-cadherin hybrid molecular binding strength, while retaining its cytosolic interactions and downstream signaling capabilities. The DNA-E-cadherin hybrid facilitates strong and reversible cell-cell adhesion in E-cadherin deficient cells by forming mechanotransducive adherens junctions. We assess the direct influence of cell-cell adhesion strength on intracellular signaling and collective cell dynamics. This highlights the scope of DNA nanotechnology as a precision technology to study and engineer cell collectives.