Construction of artificial human peritoneal tissue by cell-accumulation technique and its application for visualizing morphological dynamics of cancer peritoneal metastasis.

Human peritoneum is composed of mesothelial monolayer and stromal tissue containing microvasculature. Dissemination and infiltration of cancer cells to the peritoneum result in cancer peritoneal metastasis which is an important prognostic factor of intraperitoneal or intrapelvic carcinoma. To elucidate an initial metastatic mechanism of cancer cells, in vitro human peritoneal models are demanded. In this study, we created a three-dimensional artificial human peritoneal tissue (AHPT) harboring the blood or lymphatic vascular network by cell-accumulation technique. Morphological analysis demonstrated that AHPT had mesothelial monolayer with polygonal flat cells with apical microvilli, and stroma-like structure containing fibroblasts surrounded by extracellular matrix and blood or lymphatic vascular network. To assess AHPT as a tool for cancer peritoneal metastasis model, colon and ovarian cancer cells (HT-29 and SKOV3) were seeded onto AHPT. HT-29 cells showed poor metastatic characteristics forming thick clusters in mesothelial layer without invasion into stroma-like structure. On the other hand, SKOV3 cells rapidly invaded intercellular spaces between mesothelial cells and then spread over the stroma-like structure accompanying lymphatic invasion, showing aggressive metastatic characteristics. These results demonstrated that the metastatic dynamics of cancer cells with different characteristics are able to visualized by AHPT, suggesting that this tissue can be a powerful tool for the basic research of cancer peritoneal dissemination and metastasis.