Abstract 4251: Development of spheroids derived from tumor biopsies and patient-derived xenografts using magnetic 3D bioprinting
Authors: Tseng Hubert , Gage Jacob A. , Desai Pujan K. , Brobey Reynolds , Skinner Sheri , Dehghani Mehdi , Rosenblatt Kevin P. , Li Wenliang , Amato Robert J. , Souza Glauco R. 
Published: July 2016

Abstract
Precision medicine holds the promise of designing patient-specific therapies to improve therapeutic efficiency. However, the scarcity of tumor and biopsy tissue is a limiting factor in the development of diagnostic assays. Cells isolated from these tissues could be used to overcome these issues, while serving as the basis for assays to diagnose and guide treatment. It is critical that the in vitro culture of these cells be performed in three-dimensional (3D) environments that can better replicate the native tumor microenvironment. However, currently available 3D cell culture platforms, like Matrigel, suffer from technical limitations in reproducibility and handling that make the development of such assays difficult.
Towards that end, this study isolates cells from human prostate cancer (PC) and renal cell carcinoma (RCC) tumor biopsies and patient-derived xenografts (PDX) and prints them into spheroids using magnetic 3D bioprinting. The core principle of magnetic 3D bioprinting is the magnetization of cells and their aggregation using mild magnetic forces. Once aggregated, these cells form spheroids that mimic native tumor environments in extracellular matrix and cell-cell and cell-ECM interactions. This technique can be used to actively magnetize cells and generate spheroids from a scarce cell source, while overcoming the limitations of other 3D cell culture platforms.
In this study, we demonstrated our ability to print spheroids from cells isolated from human tumor biopsies and PDX. Isolation techniques ranging from simple mincing and filtration to enzymatic digestion were employed. Next, these cells were magnetized
by incubation with a biocompatible magnetic nanoparticle assembly, NanoShuttle. Once magnetized, these cells were printed into spheroids of varying sizes, from 1,000-20,000 cells, in 384-well plates. These cells were cultured for days, after which viability was measured using CellTiter-Glo.
Our preliminary studies demonstrated our ability to isolate cells and print them into spheroids. Isolation was best with either mincing and filtration alone or collagenase II (400 U/mL) digestion for 1 h. These cells were then successfully magnetized and printed into spheroids, which remained viable after 72 h. Spheroids of 10,000-20,000 cells were the most successful, and further optimization is needed to reduce the size needed for viable spheroids to take full advantage of scarce resources such as tumor biopsies. We also demonstrated the ability to assay compound toxicity, showing a dose-dependent toxicity on spheroids derived from PDX tumors.
In all, we demonstrated our ability to isolate cells from human tumor biopsies and PDX models and print them into spheroids with high throughput. These preliminary results will serve as a platform for the further development of precision medicine assays to optimize PC and RCC treatment.
Citation Format: Hubert Tseng, Jacob A. Gage, Pujan K. Desai, Reynolds Brobey, Sheri Skinner, Mehdi Dehghani, Kevin P. Rosenblatt, Wenliang Li, Robert J. Amato, Glauco R. Souza. Development of spheroids derived from tumor biopsies and patient-derived xenografts using magnetic 3D bioprinting. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4251.