Abstract C42: Cell culture under perfusion conditions reduces cellular metabolic stress and mimics the in vivo physiologic environment in pancreatic cancer
Authors: Hughes Daniel , Willenbrock Frances , Soonawalla Zahir , Reddy Srikanth , Silva Michael , Mukherjee Somnath , O'Neill Eric 
Published: March 2020

Abstract
Introduction: Tumor responsiveness to chemotherapy in PDAC varies significantly across patients, and some patients may succumb to very early recurrent disease (within 6 months). This reinforces the need to establish an accurate model that preserves the tumor microenvironment in the ex vivo, allowing a personalized drug screen for patients to identify optimal regime of therapy. Many aspects of tumor biology are difficult to reproduce in ex vivo, e.g., the tumor-host interaction and tumor vascularity. The current standard of 2D cell culture is that the medium is exchanged at defined time points (i.e., static culture). However, this is not a physiologically representative model as cells are maintained in either a nutrient and substrate “hyper-replete” or deplete environment, rather than an epistatic supply. Moreover, episodic media replacement creates significant and abrupt changes to the culture environment and availability of substrates, which induces cellular metabolic stress. We evaluated the role of perfusion culture to establish whether this technique reduced metabolic stress and created a physiologically representative model of the in vivo tumor environment by comparing in vitro cell responses to core biopsies from patients with pancreatic cancer.
Methods: Cells were cultured and maintained either in static culture (serving as a control, with media exchange every 72 hours) or in a nutritionally replete condition with a constant low perfusion rate of media exchange over 7 days. Daily media extraction was performed in order to evaluate the metabolic activity and viability of cells in addition to quantify the availability of metabolic substrates. Core biopsies were temporarily fixed in low melting agarose gel prior to creating multiple tissue slices through the tumor. Tissue slices were then cultured either in static culture (as control) or under perfusion conditions. Tumors were also subjected to histologic assessment of the tissue morphology, cellular function, and components of the microenviroment.
Results: Under conventional static culture, a decrease in the quantity of metabolic substrates was observed over time, indicating metabolic activity of cells in static culture was suppressed (noted by downregulation of mTOR pathway products, notably phosphorylated S6). Under perfusion conditions, glucose concentration was maintained over 7 days, indicating cells were able to maintain metabolic activity. Tissue sections were similarly evaluated for metabolic stress and will be presented.
Conclusion: This platform highlights the considerable metabolic stress that cells undergo while under conventional static culture. Perfusion culture serves as a technique to reduce cellular metabolic stress in addition to creating a physiologically representative model ex vivo.
Citation Format: Daniel Hughes, Frances Willenbrock, Zahir Soonawalla, Srikanth Reddy, Michael Silva, Somnath Mukherjee, Eric O'Neill. Cell culture under perfusion conditions reduces cellular metabolic stress and mimics the in vivo physiologic environment in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C42.