Morphological characterization of Etv2 vascular explants using fractal analysis and atomic force microscopy

Area of Science:

• Vascular Biology
• Tissue Engineering
• Developmental Biology

Background:

• Rapid vascular network formation is crucial for tissue explant integration.
• Current angiogenesis methods often result in unstable or mechanically weak vasculature.
• The transcription factor Ets variant 2 (Etv2) is key in embryonic vascular development and is reactivated in regeneration.

Purpose of the Study:

• To investigate the role of Etv2 upregulation in creating stable vascular beds.
• To assess the impact of Etv2 on vascular complexity, homogeneity, and mechanical stability.
• To evaluate Etv2's influence on vascularization within a tumor microenvironment.

Main Methods:

• Cultured human umbilical vein endothelial cells (HUVECs) and adult endothelial cells (ECs) with and without Etv2.
• Quantified vascular bed complexity using fractal dimension and lacunarity.
• Assessed mechanical properties with atomic force microscopy (AFM) and evaluated endothelial cell (EC) integrity markers.

Main Results:

• Etv2+ HUVECs showed increased branching, density, and homogeneity, with decreased stiffness in vitro and in vivo.
• Co-culture with colon tumor organoids modulated Etv2+ HUVEC vascularization, increasing density and homogeneity.
• Fractal dimension, lacunarity, and AFM provided insights into vascular stability comparable to traditional metrics.

Conclusions:

• Etv2 upregulation enhances the formation of stable, well-integrated vascular networks.
• Novel quantitative metrics like fractal dimension and lacunarity can assess vascular stability.
• Etv2 is a promising target for improving vascularization strategies in tissue engineering and regenerative medicine.