Revascularization in the rabbit hindlimb: dissociation between capillary sprouting and arteriogenesis

Area of Science:

• Vascular biology and regenerative medicine.
• Animal models for peripheral vascular disease research.

Background:

• Hindlimb ischemia models are crucial for studying peripheral vascular disease and testing therapies.
• Understanding revascularization requires examining the interplay of ischemia, growth factors, and vessel development.

Purpose of the Study:

• To evaluate the temporal relationship between ischemia, vascular endothelial cell growth factor (VEGF) release, angiogenesis, arteriogenesis, and reserve blood flow.
• To differentiate the roles of angiogenesis and arteriogenesis in functional recovery after hindlimb ischemia.

Main Methods:

• New Zealand White rabbits underwent femoral artery removal.
• Measurements included hindlimb blood flow, lactate production, VEGF content, capillary density (angiogenesis marker), and angiographic score (arteriogenesis marker) at various time points (0-40 days).

Main Results:

• Maximal capillary sprouting (angiogenesis) occurred by day 5, coinciding with reduced blood flow, increased lactate, and detectable VEGF.
• Larger collateral vessel growth (arteriogenesis) began after day 10, correlating with improved reserve blood flow but not ischemia or VEGF levels.

Conclusions:

• Angiogenesis and arteriogenesis follow distinct temporal patterns after femoral artery removal.
• While VEGF may stimulate capillary sprouting, it doesn't guarantee improved collateral flow.
• Development of larger collateral vessels is key to functional recovery of blood flow, occurring when VEGF is undetectable.