Tryptophanyl-tRNA synthetase-derived polypeptides useful for the regulation of angiogenesis

A method of assaying the angiogenesis inhibiting activity of a composition, the method comprising:

• a) injecting a solution of a composition to be assayed into an eye of a newborn mouse on about day 7 or 8 postnatal;
• b) euthanizing the mouse on about day 12 or 13 postnatal and removing the injected eye therefrom;
• c) excising the retina from the injected eye and staining the retina with a rabbit anti-mouse collagen IV antibody and a fluorescent-labeled goat anti-rabbit IgG antibody to visualize the vascular network of the retina;
• and
• d) microscopically comparing the degree of vascularization of the deep outer vascular plexus of the retina exposed to the composition to be assayed with the degree of vascularization of a control retina from a mouse eye of the same age, and similarly stained, which was not exposed to the composition;
• wherein a substantially lower degree of vascularization in the treated retina exposed to the composition compared to the degree of vascularization of the control retina indicates inhibition of angiogenesis by said composition.