Selective inhibition of angiogenesis in small blood vessels and decrease in vessel diameter throughout the vascular...

Area of Science:

• Developmental biology
• Angiogenesis research
• Pharmacology

Background:

• The chorioallantoic membrane (CAM) of quail embryos is a widely used model for studying angiogenesis.
• Steroids are known to influence vascular development, but their specific effects on microvascular branching are not fully understood.

Purpose of the Study:

• To quantify the effects of triamcinolone acetonide (TA) on the branching morphology of the angiogenic microvascular tree in quail embryo CAM.
• To investigate how TA influences key vascular parameters like vessel diameter, fractal dimension, and vessel densities.

Main Methods:

• Quail embryos at embryonic day 7 were treated with varying concentrations of TA (0-16 ng/mL) applied topically to the CAM.
• Microscopic images of arterial end points were analyzed using VESGEN software for generational analysis of vessel branching.
• Vascular parameters including vessel diameter (D(v)), fractal dimension (D(f)), and densities (A(v), L(v), N(v), Br(v)) were quantified.

Main Results:

• Increasing TA concentrations significantly decreased vessel density (up to 34%) across parameters A(v), L(v), Br(v), N(v), and D(f).
• TA selectively inhibited the growth of smaller vessels (generations G(7)-G(10)), reducing length (L(v)) and number (N(v)).
• Vessel diameter (D(v)) was reduced throughout all vascular generations (G(1)-G(10)).

Conclusions:

• Triamcinolone acetonide selectively inhibits angiogenesis of smaller blood vessels within the CAM.
• TA also decreases the vessel diameter of all vessels, indicating a broad impact on vascular morphology.
• The VESGEN analysis provides a quantitative method to assess steroid-induced changes in vascular development.