Abstract 5085: A preclinical model using perfusion air culture of tumor tissue slices for personalized medicine
Authors: Dong Meng , Böpple Kathrin , Winkler Bernd , Kleih Markus , Schüler Julia , Davies Emma , Metsalu Tauno , Walles Heike , Kopp Hans-Georg , Essmann Frank , Aulitzky Walter E. 
Published: September 2020

Abstract
For personalized medicine it is crucial that a preclinical model captures the complex tumor biology in vitro in order to individually predict in vivo therapy of tumors. Precision-cut tumor slices maintain tissue heterogeneity with regard to different cell types and preserved native microenvironment. To enable the use of tumor slices as preclinical model that fulfills these criteria we developed a perfusion air culture (PAC) system with continuous and precisely controlled oxygen, medium and drug supply. In the PAC system, precision-cut tumor slices are kept in-between two organotypic supports fixed in a special chamber and placed inside of a 50 mL tube with air exchange capacity housed in a standard CO2-incubator.
To evaluate the PAC system, cultured tumor slices from mouse xenografts (MCF7, H1437) and primary human ovarian tumors (phOVT) were compared to in vivo source tissues using immunohistochemistry for morphology, proliferation, DNA damage, apoptosis, and transcriptional biomarkers for cellular stress response. Results show that viability and morphology of the tumor slices are preserved for more than 7 days in the PAC system. We also compared the PAC system with the commonly used static Millipore filter (MF) system which cultures slices on a filter support at an air-liquid interface and gives rise to intra-slice gradients. Both, mouse xenografts and 9 of 15 phOVT tissue slices showed a gradient of cell proliferation and biomarker expression in the MF system while no gradient was detected in slices cultured in the PAC system. Analysis of the culture media revealed lower glucose consumption and lactate production in the PAC system as compared to the MF system indicating more efficient oxygen supply.
To analyze therapy response, Cisplatin was applied to phOVT tumor slices for 3 days. Cisplatin treatment was accompanied by minor increase of γ-H2AX in both MF and PAC systems while only in the PAC system strongly enhanced cleavage of caspase-3 was observed, indicating that the PAC system is suitable to assess functional response to drug treatment. To test whether the PAC system is also suitable for the detection of immune response in tumor slices, we analyzed the immune cells of tissue slices before and after cultivation. The patient specific immune cells and their composition is preserved throughout the culture period in the PAC system.
In conclusion, cultivation of tumor tissue slices in the PAC system provides an ex vivo model that preserves tumor heterogeneity and native microenvironment. Because the PAC system facilitates homogenous and precisely controlled supply of oxygen, nutrients and drugs, it allows long-term culture of tumor tissue and analysis of therapy response - including immune therapy. We conclude that the newly developed PAC system is suitable to perform patient specific ex vivo tests and thus allows personalized therapy adaption.
Citation Format: Meng Dong, Kathrin Böpple, Bernd Winkler, Markus Kleih, Julia Schüler, Emma Davies, Tauno Metsalu, Heike Walles, Hans-Georg Kopp, Frank Essmann, Walter E. Aulitzky. A preclinical model using perfusion air culture of tumor tissue slices for personalized medicine [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5085.