Abstract 3700: A window into human tumor progenitor cell subsets: Functionalizing a novel platform, the micropallet array, for molecular evaluation of single adherent cells with defined cell surface phenotype
Authors: Nelson Edward L. , Westerhof Trisha , Giammo Giulia , Li Guann-Pyng , Bachman Mark 
Published: August 2018

Abstract
The recognition of unique cellular elements such as cancer stem cells (CSCs) and processes such as epithelial to mesenchymal transition (EMT) raises predictions that are biologically provocative and clinically impactful. To better understand the interplay between individual cellular elements, and improve current molecular and cellular characterizations of an individual's cancer, the development of a technology to rapidly identify, isolate, and evaluate a patient's tumor biopsy at single cell resolution is required. The micropallet array is a photoresist-based technology that provides a means to isolate and recover single adherent cells on individual pedestals, termed “micropallets”. We have functionalized this platform to identify cells of defined surface phenotype in heterogeneous mixtures, such as would be obtained from a tumor tissue biopsy, by incorporating multicolor immunofluorescent confocal imaging to interrogate the expression pattern of up to 6 different cell surface molecules on heterogeneous cell mixtures distributed over a micropallet array. The ability to interrogate the expression of multiple cell surface molecules provides a critical addition to the existing micropallet array platform, in that it enables the identification, enumeration, and along with the previously demonstrated capacity to release and retrieve micropallets carrying single adhered cells, the study of single cells of defined cell surface phenotype. Herein, we report functionalization of the platform and its application to human breast tumors as a proof of principle for its application. We demonstrate the capacity to identify, retrieve, and study single adherent cells that are characterized as; putative CSCs, endothelial progenitor cells, bulk malignant epithelium, leukocytes, and cells with hybrid cell surface phenotype suggestive of cells undergoing EMT, using a panel of antibodies to detect select surface molecules (CD24, CD44, CD45, CD133, CD309, and CD326 [Epithelial Surface Antigen or ESA]). Furthermore, we have applied single cell nanoString analyses to characterize their respective molecular profiles. This provides a unique and unmatched platform for the study of minimally perturbed, primary human tumor cellular subsets, obtained from standard small volume tumor biopsies, and to address biological and cancer biology questions, at single cell resolution, that have been heretofore beyond reach.
Citation Format: Edward L. Nelson, Trisha Westerhof, Giulia Giammo, Guann-Pyng Li, Mark Bachman. A window into human tumor progenitor cell subsets: Functionalizing a novel platform, the micropallet array, for molecular evaluation of single adherent cells with defined cell surface phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3700.