Orientational correlations in mammalian cells: unveiling the influence of intercellular and cell-Matrix Interactions

Mammalian cells have unique and complex ways to communicate with each other and establish mutual correlations, akin to human beings and social animals. These correlations are evident in various cellular behaviors, such as collective migration, orientation alignment, and force balance, which hold great significance in understanding different physiological processes but still lack clarity. Spindle-shape myoblasts, as an active system, can spontaneously form nematic order within monolayers, and this process is closely related to intercellular correlations. In our study, we demonstrate that the establishment of long-range orientation correlation among myoblasts is a result of both cell-cell and cell-matrix interactions. By observing the evolution of correlation length with varying cell density and blocking cell proliferation or intercellular protein contacts, we conclude that intercellular interactions influence correlations both physically and biologically. Additionally, we investigate how cell-matrix interaction plays a role in cell correlation using Polydimethylsiloxane (PDMS) substrates with varying stiffness (from 1.8kPa to 500kPa). This complex situation involves focal adhesions acting as motors or friction, actomyosin contractility, cell morphology, and intercellular mechanical communication through substrate deformation. Our research aims to provide valuable insights for further studies on topics such as wound healing, myogenesis, cell jamming, topological defects, 3D morphogenesis, and other collective behaviors.