Figure 3. Ectopic sources of Epo in tissues of patients with pancreatic diseases.

(A) Remnants of Epo-producing islets in degrading CP-parenchyma. (B) Epo-negativity of tumor cells in primary pancreatic lesion, except for sporadic focal staining observed in intracellular vacuoles of tumor cells (C, arrows and inset). Peripheral capillaries (C, arrowheads) and vasa vasorum (D, arrowheads) of bigger vessels frequently demonstrated Epo positivity in PDAC and CP. (E, F) In liver, cytoplasmic staining of hepatocytes was strong in areas directly bordering Epo-negative metastatic tumor cells and inflammatory infiltrates, but faded away distally, thus pointing to the spatially regulated de novo synthesis and creation of multiple Epo-rich niches. Insets in A, D and E depict negative (isotype IgG) controls; insets in C and F show high-magnification (×630) images of staining patterns in intracellular vacuoles of tumor cells and cytoplasm in hepatocytes.