Orthotopic model of pancreatic cancer using CD34+ humanized mice and generation of tumor organoids from humanized tumors

Abstract

In pancreatic cancer (PC) as intractable solid cancer, current research is focused mainly on targeted immunotherapies such as antibodies and immune cell modulators. To identify promising immune-oncological agents, animal models that recapitulate the essential features of human immune status are essential. To this end, we constructed an orthotopic xenograft model using CD34⁺ human hematopoietic stem cell-based humanized NOD scid gamma mouse (NSG) mice injected with luciferase-expressing PC cell lines AsPC1 and BxPC3. The growth of orthotopic tumors was monitored using noninvasive multimodal imaging, while the subtype profiles of human immune cells in blood and tumor tissues were determined by flow cytometry and immunohistopathology. In addition, the correlations of blood and tumor-infiltrating immune cell count with tumor extracellular matrix density were calculated using Spearman's test. Tumor-derived cell lines and tumor organoids with continuous passage capacity in vitro were isolated from orthotopic tumors. It was further confirmed that these tumor-derived cells and organoids have reduced PD-L1 expression and are suitable for testing the efficacy of specific targeted immunotherapeutic agents. These animal and culture models could facilitate the development and validation of immunotherapeutic agents for intractable solid cancers including PC.

Keywords: Humanized mice; Orthotopic model; Pancreatic ductal adenocarcinoma; Tumor-derived organoids; Tumor-infiltrating immune cells.