Fingering instabilities in tissue invasion: an active fluid model

TL;DR

This paper introduces a minimal active fluid model to explain fingering instabilities in tissue invasion, predicting tumor behavior and providing insights into metastasis and other biological processes.

Contribution

The study develops a simple, analytically tractable active fluid model with four parameters to describe tissue invasion and fingering instabilities in cancer and biological tissues.

Findings

Model explains tumor fingering instabilities based on active traction and growth.

Predicts tumor size at metastasis onset and number of invasive fingers.

Applicable to wound healing and developmental patterning processes.

Abstract

Metastatic tumors often invade healthy neighboring tissues by forming multicellular finger-like protrusions emerging from the cancer mass. To understand the mechanical context behind this phenomenon, we here develop a minimalist fluid model of a self-propelled, growing biological tissue. The theory involves only four mechanical parameters and remains analytically trackable in various settings. As an application of the model, we study the evolution of a 2D circular droplet made of our active and expanding fluid, and embedded in a passive non-growing tissue. This system could be used to model the evolution of a carcinoma in an epithelial layer. We find that our description can explain the propensity of tumor tissues to fingering instabilities, as conditioned by both the magnitude of active traction and the growth kinetics. We are also able to derive predictions for the tumor size at the onset of metastasis, and for the number of subsequent invasive fingers. Our active fluid model may help describe a wider range of biological processes, including wound healing and developmental patterning.