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. 2019 Oct 17;9(26):8018–8025. doi: 10.7150/thno.38587

Figure 1.

Figure 1

Representative solid tumor IHC staining to show “leaky” vs “non-leaky” tumor types. Human MCF-7 breast cancer (A) and BxPC3 pancreatic cancer (B) tissues were retrieved from our historical samples and OCT embedded for frozen section. Two-color immunohistochemistry staining was performed. The endothelial cell marker (CD31) was labeled in green (FITC), and the pericyte marker (NG2) was labeled in red (Alexa Fluor 594). Nuclear was labelled by Hoechst dye. Zoom in pictures to show the extent of pericyte coverage in each tumor type. While the blood vessels in MCF-7 tumor exhibit low pericyte coverage and round-like structure, we frequently observed structurally collapsed or obstructed blood vessels in BxPC3 tumor, which also contain high pericyte coverage. Accordingly, we assigned MCF-7 and BxPC3 tumors into “leaky” and “non-leaky” categories, respectively. The important tumor microenvironment (TME) characteristics are summarized. In our opinion, while EPR effect may play a key role in the “leaky” tumor (A, lower panel), transcytosis becomes more important in the “non-leaky” tumor type (B, lower panel).