T. Ivanics1, J. R. Bergquist1, R. P. Graham2, G. Liu1, M. C. Hernandez1, L. Yang1, M. J. Truty1 1Mayo Clinic,Department Of Surgery,Rochester, MN, USA 2Mayo Clinic,Department Of Laboratory Medicine And Pathology,Rochester, MN, USA
Introduction:
Patient-derived xenograft (PDX) models are increasingly being used to study cancer and have been shown to be strong predictors of response to therapy because they accurately recapitulate tumor phenotype and biology. We describe recent efforts to develop and optimize an ex-vivo assay utilizing thin slices of PDX tumors to facilitate rapid high throughput screening of multiple agents prior to formal in-vivo PDX testing.
Methods:
PDX tumors were embedded in 2% agarose and sliced into 100-400μm slices using a vibrating microtome. These tissue slices were then cultured ex-vivo for 5 days utilizing 2 different culture
Methods: Organotypic Teflon inserts (0.4μm pore) and Gelfoam. Media was DMEM with 10%Fetal-Bovine-Serum and 1% Antibiotic and was changed daily.
Results:
Tissue viability was maximized at 5 days using the 200μm slice thickness although 300μm also showed good viability. The culture method with maximum viability was the Organotypic Teflon insert (Table). 100μm slices were difficult to handle without offering significant benefit in tissue viability. 400μm slices showed extensive ischemic necrosis.
Conclusion:
Utilization of a vibrating microtome makes thin slices of tumor easy to create. This data provides encouraging results showing viability of tumor slices in ex-vivo culture for up to 5 days. 200µm slice thickness maintained on organotypic Teflon inserts provides optimal conditions for maintenance of tissue viability. 400μm slices are too thick likely due to greater oxygen diffusion distance. This novel method allows for pre-screening of therapeutic agents prior to formal in-vivo testing and can ultimately be used to individualize treatment approach for cancer patients.
