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Stem Cells International
Volume 2016 (2016), Article ID 1652389, 14 pages
Research Article

Optimized Stem Cell Detection Using the DyeCycle-Triggered Side Population Phenotype

1Institute of Immunobiology, Kantonsspital St. Gallen, Rorschacherstrasse 95, 9007 St. Gallen, Switzerland
2Internal Medicine V, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria
3Medical Clinic III for Oncology, Hematology and Rheumatology, University Clinic Bonn (UKB), Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
4Tyrolean Cancer Research Institute, Innrain 66, 6020 Innsbruck, Austria

Received 14 July 2015; Accepted 31 August 2015

Academic Editor: Hannele T. Ruohola-Baker

Copyright © 2016 Maximilian Boesch et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Tissue and cancer stem cells are highly attractive target populations for regenerative medicine and novel potentially curative anticancer therapeutics. In order to get a better understanding of stem cell biology and function, it is essential to reproducibly identify these stem cells from biological samples for subsequent characterization or isolation. ABC drug transporter expression is a hallmark of stem cells. This is utilized to identify (cancer) stem cells by exploiting their dye extrusion properties, which is referred to as the “side population assay.” Initially described for high-end flow cytometers equipped with ultraviolet lasers, this technique is now also amenable for a broader scientific community, owing to the increasing availability of violet laser-furnished cytometers and the advent of DyeCycle Violet (DCV). Here, we describe important technical aspects of the DCV-based side population assay and discuss potential pitfalls and caveats helping scientists to establish a valid and reproducible DCV-based side population assay. In addition, we investigate the suitability of blue laser-excitable DyeCycle dyes for side population detection. This knowledge will help to improve and standardize detection and isolation of stem cells based on their expression of ABC drug transporters.