Microvessel formation from mouse embryonic aortic explants is oxygen and VEGF dependent

Area of Science:

• Developmental Biology
• Vascular Biology
• Cell Biology

Background:

• Angiogenesis, the formation of new blood vessels, is a critical process in embryonic development.
• Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis.
• The role of oxygen levels in modulating VEGF-mediated angiogenesis from the embryonic aorta requires further elucidation.

Purpose of the Study:

• To investigate the interplay between oxygen tension and VEGF in driving angiogenesis from embryonic mouse aorta explants.
• To determine how low oxygen conditions affect the expression of VEGF receptors in the embryonic aorta.

Main Methods:

• Culture of mouse embryonic aorta explants in a 3D collagen gel matrix.
• Treatment with varying concentrations of VEGF under different oxygen conditions (5% O(2) vs. room air).
• Assessment of capillary-like structure formation using markers like CD31, Flk-1, and Gs-IB(4); electron microscopy for structural confirmation; and inhibition studies using soluble Flt-1 fusion protein or anti-VEGF antibodies.

Main Results:

• VEGF significantly stimulated the formation of capillary-like structures in explants cultured under 5% O(2), but not room air, in a dose-dependent manner.
• VEGF-induced angiogenesis was inhibited by blocking VEGF activity, confirming its specificity.
• Low oxygen (5% O(2)) upregulated the expression of Flk-1 (VEGF receptor 2) in embryonic aorta explants compared to room air.

Conclusions:

• Low oxygen tension upregulates Flk-1 expression in the embryonic aorta in vitro.
• This upregulation makes the embryonic aorta more responsive to VEGF, thereby promoting angiogenesis.
• Oxygen levels are a critical environmental factor influencing VEGF-mediated vascular development.