[Establishment and characterization of patient derived xenograft model of malignant peritoneal mesothelioma in nude mice].

To establish patient derived xenograft (PDX) model of malignant peritoneal mesothelioma (MPM), and to identify the key characteristics of tumor biology of the model, so as to provide an experiment platform for studying the pathologic mechanisms and new therapeutic strategies for MPM. Surgically excised MPM tumor tissues were inoculated subcutaneously in BALB/c-nu/nu mice for 3 stable passages. In the 4th passage, the subcutaneous tumors were harvested under aseptic conditions, cleaned and made into MPM tumor cell homogenate. Four nude mice (two males and two females) were selected and one male and one female nude mouse were inoculated in the abdominal cavity at the dose of 100 μL, others were inoculated at a dose of 200 μL. The PDX model of MPM was established. The changes of body mass in nude mice were measured regularly, the extent of abdominal and pelvic tumors was judged by experimental peritoneal cancer index (ePCI) score, and the pathologic characteristics of tumors were analyzed. The subcutaneous and abdominal animal models of MPM were successfully established. The subcutaneous tumor model grew into tumor on the 20th day, followed by a slow growth stage between the 20th and 29th day, then a rapid growth stage between the 30th and 57th day. According to the dose of tumor cells (100, 200 μL) and timing (14th and 69th days after grafting), the abdominal tumor model successfully simulated the early and late clinical stages of MPM. The HE staining results of the MPM nude mice model showed that the tumor was epithelial mesothelioma and invaded most of the organs, including liver, spleen, pancreas, mesentery. Immunohistochemical staining for calretinin, cytokeratin 5/6, WT1 and Ki-67 were positive. Whole-genome exon sequencing identified 26 and 36 high frequency gene mutations in tumors derived from the PDX model and clinical sample from patients, including 21 common gene mutations. The PDX model of MPM is established. The model is characterized by highly malignant tumor with rapid growth and high invasiveness.