Figure 4. Association of network formation ability of HME cells with VEGF expression in gliblastoma U87MG or U118MG cells in co-cultures.

U87MG and U118MG cells were grown separately on chamber slides and treated with different doses of photofrin. Treatments: control (CTL), 10, 20, and 50 µg/ml photofrin incubation for 4 h followed by irradiation with 670 nm light dose of 1 J/cm². After 24 h, HME cells were co-cultured with glioblastoma cells. Quantitative data are shown as means ± SEM of six independent experiments in each group. Significant difference between CTL and a treatment was indicated by *P<0.05 or **P<0.01. (a) Effect of photofrin based PDT on network formation ability of HME cells in co-cultures. The co-cultures were terminated at 72 h and immunohistochemically stained for expression of the von Willebrand factor VIII in HME cells. Then, in vitro networks were quantified. (b) Effect of photofrin based PDT on VEGF expression in glioblastoma cells in co-cultures. Following the same treatments and incubations as described above, another set of same network formation experiments were conducted for in situ immunofluorescence microscopic studies using the FITC conjugated anti-VEGF antibody to determine the levels of VEGF expression in glioblastoma cells in co-cultures.