Formation and maturation of the native cerebral collateral circulation

Area of Science:

• Vascular Biology
• Developmental Biology
• Genetics

Background:

• Native collateral circulation protects tissues from obstructive vascular disease.
• Significant individual variation in collateral extent suggests genetic and environmental influences.
• The timing and mechanisms of native collateral formation remain largely unknown.

Purpose of the Study:

• To investigate the developmental timing and strain-specific differences in collateral formation.
• To identify factors influencing collateral development by comparing mouse strains with distinct adult collateralization.

Main Methods:

• Comparative analysis of collateral development in BALB/c and C57BL/6 mouse embryos.
• Vascular casting, fixation, and staining techniques to visualize collateral plexus formation.
• Examination of vascular patterning from embryonic day 9.0 to postnatal day 21.

Main Results:

• A primary collateral plexus began forming by embryonic day 15.5, with significant strain differences by embryonic day 18.5 (60% fewer vessels, smaller diameter in BALB/c).
• Early vascular patterning at embryonic day 9.0 was similar, but differences emerged by embryonic day 12.5 (less branching, larger diameter in BALB/c).
• Postnatal maturation (P1-P21) showed comparable pruning but less diameter and tortuosity increase in BALB/c, despite lower VEGF-A and PDGF-B expression.

Conclusions:

• Collateral formation occurs late in vascular development and involves postnatal maturation processes.
• Genetic background profoundly influences collateral development, affecting vessel density, diameter, and maturation.
• Understanding these developmental processes is key to identifying factors that modulate collateralization.