Dll4-containing exosomes induce capillary sprout retraction in a 3D microenvironment

Area of Science:

• Vascular Biology
• Cell Signaling
• Extracellular Vesicles

Background:

• Delta-like 4 (Dll4) is a Notch ligand crucial for vascular development and angiogenesis.
• Dll4 signaling, mediated by cell contact or exosomes, regulates tip and stalk cell fates.
• The role of Dll4-containing exosomes in influencing existing capillary tip cells remained unclear.

Purpose of the Study:

• To investigate the impact of Dll4-containing exosomes on capillary tip cells and angiogenesis.
• To elucidate the mechanisms by which Dll4 exosomes affect endothelial cells.

Main Methods:

• Utilized a 3D microfluidic device combined with time-lapse confocal microscopy.
• Tracked the behavior of Dll4-containing exosomes and their effects on endothelial tip cells in a collagen matrix.

Main Results:

• Dll4-containing exosomes induced tip cell filopodia loss and capillary sprout retraction.
• Exosomes facilitated Dll4 protein transfer to distant tip cells, activating Notch signaling.
• Continuous exosome application reduced sprout formation, increased cell motility, and suppressed proliferation.

Conclusions:

• Dll4-containing exosomes exert novel inhibitory effects on angiogenesis.
• Exosomes represent a significant mechanism for Dll4-mediated regulation of vascular development.
• Dll4 exosomes offer potential therapeutic targets for modulating angiogenesis.