Abstract 369: Automating recovery of spiked tumor cells from blood

Abstract

Abstract The isolation and study of circulating tumor cells (CTC) enables personalized medicine solutions, monitoring of therapeutics (theragnostics), and monitoring of minimal residual disease (MRD); culturing these rare cells is a frequent goal in cancer research, however the common methods for their isolation (gradient centrifugation, lysis buffer) are damaging to these cells, and many emerging technologies leave the cells bound in a consumable, bound to a biomarker or in a state that is difficult to use in cell culture. Further, the anuclear cells in blood greatly outnumber nucleated cells and present significant challenges to the study of the nucleated cells, for example, erythrocytes can absorb excitation or emission wavelengths in fluorescence studies, and their shape promotes rouleaux formation which can sequester the cells of interest; platelets also have a tendency to be activated by physical handling and cause aggregation that can also sequester and damage the cells of interest, and these all contain the greatest content of RNA and other markers that increase background noise in many assays. We demonstrate a new technology that automates the depletion of erythrocytes, thrombocytes, and plasma markers from, initially, small volumes of blood, using a micromachined membrane filter. We spiked small counts (10 to 1000 estimated from dilution) of tumor cell lines BT474 (breast cancer), DLD1 (colorectal cancer), and K562 (myelogenous leukemia) and other cell types into aliquots of blood. Using calcein-AM-loading to distinguish the spiked cells from blood cells, the recovery rates were determined in a flow cytometer, indicating an average of 80% ±4% (SE, N = 27) recovery of the rare cells after depletion of anuclear cells and plasma. The technology is amenable to use of beads for initial negative depletion of common nucleated cells by magnetic beads and has a recovery capacity of a few to as much as 3 million cells per specimen. Tumor cell lines alone that were run through this automation process then seeded for cell culture demonstrated growth rates indistinguishable from those seeded in similar counts in a regular cell passage. In further studies we demonstrate depletion of leukocytes with magnetic beads and of anuclear cells by filtration to handle larger blood volumes. The filtration system may be used for automated recovery of nucleated cells or cell clusters from blood or other fluid samples (liquid biopsies) without use of harsh chemicals or centrifugation, removing a common barrier for emerging analytical approaches. Citation Format: Mark Sarinana, Ky Truong, Keith Cannon, Antonio Guia. Automating recovery of spiked tumor cells from blood. [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 369.