Directed invasion of cancer cell spheroids inside 3D collagen matrices oriented by microfluidic flow in experiment and simulation

Florian Geiger,Hanna Engelke,Manuel S Brugger,Christoph Westerhausen,Lukas G Schnitzler

doi:10.1371/journal.pone.0264571

Abstract

Invasion is strongly influenced by the mechanical properties of the extracellular matrix. Here, we use microfluidics to align fibers of a collagen matrix and study the influence of fiber orientation on invasion from a cancer cell spheroid. The microfluidic setup allows for highly oriented collagen fibers of tangential and radial orientation with respect to the spheroid, which can be described by finite element simulations. In invasion experiments, we observe a strong bias of invasion towards radial as compared to tangential fiber orientation. Simulations of the invasive behavior with a Brownian diffusion model suggest complete blockage of migration perpendicularly to fibers allowing for migration exclusively along fibers. This slows invasion toward areas with tangentially oriented fibers down, but does not prevent it.

Highlights

Invasion from tumor spheroids is influenced by cellular signaling as well as by the properties of the extracellular matrix
Focusing on collagen alignment in proximity to spheroids, we find fiber orientations around the spheroid mostly along the stream lines that one would expect to result from the applied flow field around the spheroid
Analysis of the flow profile shows that the polymerized collagen gel preserves the flow field such that the fiber orientation mirrors the streamlines of the flow with the exception of the area around the upstream facing side of spheroids embedded in the collagen gel

Summary

Introduction

Invasion from tumor spheroids is influenced by cellular signaling as well as by the properties of the extracellular matrix. The onset of invasion has been described as fluidization of the spheroid, which is triggered by a phase transition from a jammed state to an unjammed, fluidlike state [1]. After this transition and the accompanying onset of invasion, single cells often start to stream out of the collective. Other molecular influences are e.g. e-cadherins and in general an epithelial to mesenchymal transition [3] To these cellular properties, characteristics of the extracellular matrix that drive such unjamming transitions have been identified. For example matrix density and extracellular confinement play a critical role in this transition [3]

Methods

Results

Conclusion