European Molecular Biology Laboratory, EMBL Barcelona, Dr. Aiguader 88, PRBB Building, 08003, Barcelona, Spain.
Institució Catalana de Recerca i Estudis Avançats, 08010, Barcelona, Spain.
Soft Matter. 2022 May 18;18(19):3771-3780. doi: 10.1039/d2sm00063f.
Multicellular aggregates are known to exhibit liquid-like properties. The fusion process of two cell aggregates is commonly studied as the coalescence of two viscous drops. However, tissues are complex materials and can exhibit viscoelastic behaviour. It is known that elastic effects can prevent the complete fusion of two drops, a phenomenon known as arrested coalescence. Here we study this phenomenon in stem cell aggregates and provide a theoretical framework which agrees with the experiments. In addition, agent-based simulations show that active cell fluctuations can control a solid-to-fluid phase transition, revealing that arrested coalescence can be found in the vicinity of an unjamming transition. By analysing the dynamics of the fusion process and combining it with nanoindentation measurements, we obtain the effective viscosity, shear modulus and surface tension of the aggregates. More generally, our work provides a simple, fast and inexpensive method to characterize the mechanical properties of viscoelastic materials.
多细胞聚集体表现出类似液体的性质。两个细胞聚集体的融合过程通常被研究为两个粘性液滴的聚并。然而，组织是复杂的材料，可能表现出粘弹性行为。众所周知，弹性效应可以阻止两个液滴的完全融合，这种现象被称为聚并受阻。在这里，我们研究了干细胞聚集体中的这种现象，并提供了一个与实验相符的理论框架。此外，基于代理的模拟表明，活性细胞波动可以控制固-流相变，表明在离解过渡附近可以发现聚并受阻。通过分析融合过程的动力学并结合纳米压痕测量，我们获得了聚集体的有效粘度、剪切模量和表面张力。更一般地说，我们的工作提供了一种简单、快速和廉价的方法来表征粘弹性材料的力学性能。
