Rozman Jan, Chaithanya Kvs, Yeomans Julia M, Sknepnek Rastko
Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford, UK.
School of Life Sciences, University of Dundee, Dundee, UK.
Nat Commun. 2025 Jan 9;16(1):530. doi: 10.1038/s41467-025-55820-2.
Complex tissue flows in epithelia are driven by intra- and inter-cellular processes that generate, maintain, and coordinate mechanical forces. There has been growing evidence that cell shape anisotropy, manifested as nematic order, plays an important role in this process. Here we extend an active nematic vertex model by replacing substrate friction with internal viscous dissipation, dominant in epithelia not supported by a substrate or the extracellular matrix, which are found in many early-stage embryos. When coupled to cell shape anisotropy, the internal viscous dissipation allows for long-range velocity correlations and thus enables the spontaneous emergence of flows with a large degree of spatiotemporal organisation. We demonstrate sustained flow in epithelial sheets confined to a channel, providing a link between the cell-level vertex model of tissue dynamics and continuum active nematics, whose behaviour in a channel is theoretically understood and experimentally realisable. Our findings also show a simple mechanism that could account for collective cell migration correlated over distances large compared to the cell size, as observed during morphogenesis.
上皮组织中的复杂组织流动由细胞内和细胞间过程驱动，这些过程产生、维持并协调机械力。越来越多的证据表明，表现为向列相序的细胞形状各向异性在这一过程中起着重要作用。在这里，我们扩展了一个活性向列顶点模型，用内部粘性耗散取代了基底摩擦，内部粘性耗散在许多早期胚胎中未由基底或细胞外基质支撑的上皮组织中占主导地位。当与细胞形状各向异性耦合时，内部粘性耗散允许长程速度相关性，从而使具有高度时空组织性的流动自发出现。我们展示了局限于通道的上皮片中的持续流动，在组织动力学的细胞水平顶点模型和连续活性向列相之间建立了联系，连续活性向列相在通道中的行为在理论上是可以理解的，并且在实验中是可以实现的。我们的研究结果还展示了一种简单的机制，该机制可以解释在形态发生过程中观察到的、与细胞大小相比在较大距离上相关的集体细胞迁移。
