Fig. 5
Histological studies of GBM after anti-angiogenic treatment. Immunofluorescence for GBM cells (green in A and C) and blood vessels (red in A) or myelin (red in C) exposed marked differences between untreated and treated tumors. In untreated controls, blood vessels (red) were abundant and larger than in the contralateral hemisphere, especially in the peripheral parts of the tumor (a). In contrast, blood vessels in animals treated with B20 anti-VEGF-antibody were accentuated in the tumor center, but otherwise not significantly different from NABT in the remaining tumor (A). Scale bar = 1 mm. The direct comparison of the amount of blood vessels in an untreated control and a treated animal showed that the overall amount of blood vessels was smaller after anti-angiogenic treatment (b). The graph depicts the percentage of blood vessel signal within the tumor of an untreated control (white box) and a treated animal (black box). Mean and SD are shown. Myelin staining showed marked differences between treated tumors and controls (c). Immunofluorescence for GBM cells (green) and myelin (red) exposed marked differences between untreated and treated tumors. Sections of three untreated controls and three animals treated with B20 anti-VEGF-antibody from experimental group 2 in similar brain regions are shown in total. The boxes (1.5 mm2) indicate the areas which are magnified in the right column in B and C. Treated tumors consisted of densely packed GBM cells (green), which were relatively homogeneous distributed over the entire tumor area and were spread around myelinated fiber bundles. The center of untreated tumors was more heterogeneous than the periphery and less myelin was identifiable between the tumor cells. The borders of untreated tumors were relatively well circumscribed, while clusters of GBM cells were observable around the margins of the main tumor mass Furthermore, tumor cell infiltration of the ventricles was observable in three treated animals (exemplary shown in C, left panel, bottom row and marked with an arrow). The amount of myelin within the tumors was quantified by automatically counting myelin bundles within the tumor and normalizing the amount of myelin signal to tumor size. The graph (d) depicts that in tumors of treated animals (black box) the myelin signal was higher than in untreated controls (white box). Mean and SEM are shown, the asterisk indicates the level of significance derived from a Mann-Whitney test