# Endothelial Sprout Formation Is Regulated by Substrate Stiffness and Notch Signaling

## TL;DR

This study explores how the stiffness of the environment and Notch signaling affect blood vessel formation in endothelial cells.

## Contribution

The study reveals that Notch signaling is mechanosensitive and contributes to sprout formation under varying substrate stiffness.

## Key findings

- Tube formation on Matrigel is influenced by substrate stiffness but not by Notch signaling.
- Spheroid sprouting is affected by both substrate stiffness and Notch signaling, with lower stiffness increasing sprouting and Notch activity.
- Notch signaling shows mechanosensitivity, linking physical environment to biological processes.

## Abstract

Angiogenesis, the process of vessel formation from pre-existing ones, is modulated by the local stiffness of the extracelluar matrix. We have previously shown that Notch signaling, a key pathway in angiogenesis, responds to substrate stiffness in endothelial cells. In the current work, we investigate the contribution of Notch signaling in angiogenesis-related in vitro assays by using VEGF and Notch inhibitors as perturbations. In addition, we investigate Notch signaling in relation to the stiffness of the respective endothelial microenvironment. While the tube formation assay on Matrigel is clearly influenced by substrate stiffness, Notch signaling seems to play no major role in this context. In contrast, spheroid sprouting is influenced by stiffness as well as Notch signaling; with decreasing stiffness, both sprouting and Notch signaling are increased. This finding adds a functional aspect to the mechanosensitivity of Notch signaling.