Figure 2

Enlarged tumor cell-containing CD31-positive blood vessels (TCCBVs) in PC14PE6-RFP tumors. (A-F) Confocal microscopic images of 15 μm-thick PC14PE6-RFP tumor sections 21 dpim showed enlarged CD31-positive blood vessels (blue) containing RFP-expressing tumor cells (red, arrowheads) in peritumoral regions (A) and tumor border areas (B). In tumor sections enlarged CD31-positive TCCBVs appear in various morphological formations resembling glomeruloid bodies (C) or garland-like vessels with intussusceptive vascular growth (D). Functionality of enlarged TCCBVs was confirmed by co-localization of CD41-positive platelets with garland-like TCCBVs (E) and Lectin-labeling of TCCBVs upon systemic injection of Lectin into PC14PE6-RFP-bearing mice. Both microscopic images indicate the connection of TCCBVs to the blood circulation. (G) RT-PCR analysis of lung, brain and liver homogenates of end-stage PC14PE6-RFP-bearing mice (28 dpim) using human- (h, 205 bp) and mouse-specific (m, 216 bp) ß-actin primers (n = 4). Human PC14PE6-RFP cells were used as a positive control for human ß-actin and as a negative control for mouse ß-actin. All images are representative examples. Scale bars represent 300 μm (A, B, F), 75 μm (C, D), and 40 μm (E).