A versatile in vivo chamber angiogenesis assay for measuring anti-angiogenic activity in mice

We recently described an in vivo angiogenesis assay for rats--an optimized Matrigel plug assay based on subcutaneously implanted chambers with fixed volume and shape. Here we examine the possibility of switching the host animal from rat to mouse, thereby reducing the requirement for test compound an order of magnitude. The chambers consist of a plexiglas ring with a 0.2 ml volume and two nylon net filters. Chambers containing growth factor-reduced Matrigel supplemented with basic fibroblast growth factor (bFGF) were subcutaneously implanted in the right flank of three different strains of mice; BALB/c, C57BL/6J, and NMRI-nu. On day 10 post-implantation: i) each chamber was taken out, ii) a picture of the induced angiogenic response was taken, and iii) the redness of the chamber content was quantified by computer image analysis. The level of bFGF-induced angiogenesis in the mouse assay was lower than in the previously published rat assay. Importantly, the background angiogenesis in mice in chambers containing Matrigel alone was correspondingly decreased. Therefore, a more sensitive threshold for the computer image analysis was used. In all three strains of mice, bFGF-induced angiogenesis was significantly increased compared to Matrigel alone. Furthermore, the positive anti-angiogenic control compound TNP-470 (10 mg/kg/d s.c.) completely inhibited the bFGF-induced angiogenesis. The in vivo chamber angiogenesis assay allows quantitative analysis of angiogenic and anti-angiogenic activity in mice. The model is very robust and only little influenced by the choice of mouse strain.