Self-assembly, Buckling & Density-Invariant Growth of Three-dimensional Vascular Networks

TL;DR

This paper models the self-assembly of 3D vascular networks using simple cell rules, revealing mechanisms for density-invariant growth, buckling, and morphology maintenance relevant to organ vasculature development.

Contribution

It introduces a novel 3D self-assembly model based on cell polarity that explains vascular network formation, buckling, and density-invariant growth.

Findings

A critical initial cell density leads to fully connected vascular networks.

Planar cell polarity drives convergent extension and growth.

Growth-induced buckling explains vascular density maintenance in pancreatic islets.

Abstract

The experimental actualisation of organoids modelling organs from brains to pancreases has revealed that much of the diverse morphologies of organs are emergent properties of simple intercellular "rules" and not the result of top-down orchestration. In contrast to other organs, the initial plexus of the vascular system is formed by aggregation of cells in the process known as vasculogenesis. Here we study this self-assembling process of blood vessels in three dimensions through a set of simple rules that align intercellular apical-basal and planar cell polarity. We demonstrate that a fully connected network of tubes emerges above a critical initial density of cells. Through planar cell polarity our model demonstrates convergent extension, and this polarity furthermore allows for both morphology-maintaining growth and growth-induced buckling. We compare this buckling to the special vasculature of Islets of Langerhans in the pancreas and suggest that the mechanism behind the vascular density-maintaining growth of these islets could be the result of growth-induced buckling.