Construction of an in-vitro peritoneal metastasis model and evaluating its feasibility for experimental peritoneal metastasis research.

Abstract

e15527 Background: Currently, a wide range of therapeutic strategies are studied and developed for the treatment of peritoneal metastasis (PM). However, there is a lack in standardized in-vitro models that accurately mimic PM. This study introduces a novel in-vitro peritoneal metastatic model (PMM) designed to enable consistent, reproducible, and physiologically relevant evaluation of potential PM therapies. Methods: Peritoneal lavage fluid was collected laparoscopically from swine and centrifuged to isolate peritoneal progenitor cells (PPC). The PPC were cultured for 7 days before introducing commercially available HT-29 colorectal cancer cells. Co-cultures were maintained until distinct metastatic nodule formation developed. The PMM was subsequently exposed to Oxaliplatin (OX) to assess treatment responses. Formed nodules were detached using Ethylenediaminetetraacetic Acid (EDTA), then isolated and quantified. Results: The approach successfully generated a dense PMM that reproduced features of early micrometastatic disease. HT-29 cells formed diverse three-dimensional nodule structures atop the two-dimensional PPC layer. Following OX exposure, variable regrowth patterns and distinct interactions with the reconstructed peritoneal surface were observed, reflecting clinically relevant heterogeneity and chemoresistance. EDTA treatment enabled efficient removal and standardized harvesting of metastatic nodules for further analyses. Conclusions: Peritoneal lavage fluid provides a reliable source of PPC for constructing a physiologically relevant PMM. This model supports standardized, quantitative assessment of therapeutic interventions and more accurately reflects the complexity and chemoresistant nature of PM compared with conventional 2D cultures. This study offers a valuable platform for advancing metastatic cancer research while reducing reliance on animal models.