Lymphangiogenesis in the developing lung promoted by VEGF-A

Area of Science:

• Pulmonary vascular development
• Neonatal lung biology
• Vascular endothelial growth factor (VEGF) signaling

Background:

• Late-stage pulmonary vascular development is critical for preterm infant survival.
• Refinement of the gas exchange unit involves capillary-airway apposition and lymphatic network formation.
• Pulmonary lymphatics are essential for maintaining interstitial fluid balance and efficient gas exchange.

Purpose of the Study:

• To investigate the impact of perinatal vascular endothelial growth factor A (VEGF-A) on late-stage pulmonary vascular development.
• To understand how VEGF-A influences the balance between blood and lymphatic vessel formation during lung organogenesis.

Main Methods:

• Conditional transgene regulation in a preclinical model.
• Analysis of distal lung tissue during the perinatal period.
• Assessment of vascular network structure, endothelial cell characteristics, and lymphatic vessel formation.

Main Results:

• A modest, pathologically relevant increase in VEGF-A during the perinatal period adversely affected gas exchange unit refinement.
• VEGF-A induction disrupted established vascular networks, increased endothelial cell number, altered ultrastructure, and reduced mesenchymal thinning.
• VEGF-A caused a threefold increase in lymphatic vessels in the distal lung, with increased VEGFR-3 levels but unchanged VEGF-D/-C mRNA.

Conclusions:

• Perinatal VEGF-A has distinct effects on lung vascular development compared to embryonic stages.
• The observed late-stage response to VEGF-A resembles that in adult lungs following injury or disease.
• VEGF-A plays a significant role in regulating the developmental balance between blood and lymphatic vasculature in the lung.