For instance, data from some therapeutic trials show tremendous promise using VEGF [14,15], but others indicate that delivery of VEGF via diffusion may not be the most effective way to induce stable vessels either to repair damaged tissues or to promote host perfusion of tissue constructs [16–18], and animal studies show that uncontrolled VEGF activity can stimulate unregulated vessel proliferation, resulting in hemangiomas [19,20]. This evidence concerns the gene VEGFA and hemangioma.