Fig 7.

The aortic ring model has been extensively used to test the activity of angiogenic regulators. This drawing lists many of the stimulators and inhibitors of aortic angiogenesis that have been reported to date. Note: ECM molecules such as laminin and type IV collagen have the capacity to promote angiogenesis, but become inhibitory at concentrations comparable to those found in mature basement membranes. Netrin-1 has been reported to inhibit or stimulate angiogenesis by different groups. PAI-1 inhibits angiogenesis when administered to aortic cultures at high dose but it is also required for vessel growth because angiogenesis is impaired in cultures of PAI-1 deficient mouse aortas.