Time to Decide? Dynamical Analysis Predicts Partial Tip/Stalk Patterning States Arise during Angiogenesis

Area of Science:

• * Molecular and cellular biology
• * Developmental biology
• * Mathematical modeling of biological systems

Background:

• * Angiogenesis is a dynamic process with poorly understood molecular timing.
• * The VEGF-notch-DLL4 pathway is crucial for tip/stalk cell competition in sprouting angiogenesis.
• * Individual cell-level dynamics of tip/stalk phenotype switching remain unclear.

Purpose of the Study:

• * To investigate how local conditions influence endothelial cell (EC) tip/stalk phenotype switching kinetics using mathematical modeling.
• * To elucidate the dynamic properties of the VEGF-notch-DLL4 signaling pathway at the individual cell level.
• * To identify factors modulating tip/stalk decision speed and explore novel intermediate cell states.

Main Methods:

• * Construction of an ordinary differential equation model for VEGF-notch-DLL4 signaling in coupled endothelial cells.
• * Simulation of cell behavior under varying local conditions to analyze phenotype switching kinetics.
• * Identification of internal cellular factors (e.g., Sirt1, Lfng1) influencing intermediate state duration.

Main Results:

• * Significant asynchrony in tip/stalk cell decisions along angiogenic vessels, accelerating competition.
• * Discovery of stable, intermediate
• partial
• cell states between tip and stalk fates.
• * Identification of Sirt1 and Lfng1 as key regulators of time spent in partial states.
• * Prediction that partial EC states occur during normal angiogenesis, especially during sprout rearrangement.

Conclusions:

• * A novel two-stage mechanism for rapid adaptive behavior in dynamic angiogenic environments is proposed.
• * Internal and external factors can modulate the speed of tip/stalk decisions in ECs.
• * Findings offer new avenues for therapeutic targeting to manipulate vascular network topology and understand angiogenesis.