Figure 1.

Growth stimulating effect of dying ECs on glioma cells. (A) HUVEC viability was significantly reduced following various hypoxic exposures, particularly at 48 h (^*P<0.05 vs. normoxic conditions, between 12 and 48 h). Cell viability was evaluated by counting viable and dead cells using a hemocytometer following the addition of 10% trypan blue. (B) Growth of U87MG cells was significantly promoted by coculture with dying ECs (^*P<0.05 vs. U87MG alone group; ^#P<0.05 vs. U87MG and EC coculture group; between days 2 and 8). Hypoxic exposure was used to induce cell death and apoptosis (2% O₂, 48 h). Cell growth was evaluated by fluorescence intensity. (C) Growth stimulating ability of dying ECs on three glioma cell lines. ECs were pretreated with 2% O₂ exposure for 48 h (^*P<0.05). (D) Growth stimulating effect of conditional medium on three glioma cell lines. Conditional medium was harvested from dying ECs cultured under 2% O₂ conditions for 48 h (^*P<0.05). All error bars represent SEM, n=4. EC, endothelial cell; HUVEC, human umbilical vascular endothelial cell.