HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) OA All Versions of this Article: 2007-0016v1 26/2/517    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints/Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Maxwell, D. J. Articles by Nolta, J. A. Search for Related Content PubMed PubMed Citation Articles by Maxwell, D. J. Articles by Nolta, J. A.

TECHNOLOGY DEVELOPMENT

Fluorophore-Conjugated Iron Oxide Nanoparticle Labeling and Analysis of Engrafting Human Hematopoietic Stem Cells

^aMolecular Imaging Center, Mallinckrodt Institute of Radiology, Department of Molecular Biology and Pharmacology,
^bDivision of Oncology, Hematopoietic Development and Malignancy Program, Washington University School of Medicine, St. Louis, Missouri, USA;
^cVascular Biology Program, Robarts Research Institute, London, Ontario, Canada;
^dDepartment of Internal Medicine, Stem Cell Program, University of California-Davis, Sacramento, California, USA;
^eDepartments of Pathology and Laboratory Medicine, Saint Louis University School of Medicine, St. Louis, Missouri, USA

Key Words. Feridex • Iron oxide • Nanoparticle • Immune-deficient mice • Human stem cells • Hematopoiesis • Transplantation

Correspondence: Jan A. Nolta, Ph.D., Stem Cell Program, University of California at Davis, Room 653, 2425 Stockton Boulevard, Sacramento, California 95817, USA. Telephone: 916-453-2335; Fax: 916-453-2173; e-mail: Jan.nolta{at}ucdmc.ucdavis.edu

Received January 15, 2007; accepted for publication November 9, 2007.
First published online in STEM CELLS EXPRESS   November 29, 2007.



The use of nanometer-sized iron oxide particles combined with molecular imaging techniques enables dynamic studies of homing and trafficking of human hematopoietic stem cells (HSC). Identifying clinically applicable strategies for loading nanoparticles into primitive HSC requires strictly defined culture conditions to maintain viability without inducing terminal differentiation. In the current study, fluorescent molecules were covalently linked to dextran-coated iron oxide nanoparticles (Feridex) to characterize human HSC labeling to monitor the engraftment process. Conjugating fluorophores to the dextran coat for fluorescence-activated cell sorting purification eliminated spurious signals from nonsequestered nanoparticle contaminants. A short-term defined incubation strategy was developed that allowed efficient labeling of both quiescent and cycling HSC, with no discernable toxicity in vitro or in vivo. Transplantation of purified primary human cord blood lineage-depleted and CD34⁺ cells into immunodeficient mice allowed detection of labeled human HSC in the recipient bones. Flow cytometry was used to precisely quantitate the cell populations that had sequestered the nanoparticles and to follow their fate post-transplantation. Flow cytometry endpoint analysis confirmed the presence of nanoparticle-labeled human stem cells in the marrow. The use of fluorophore-labeled iron oxide nanoparticles for fluorescence imaging in combination with flow cytometry allows evaluation of labeling efficiencies and homing capabilities of defined human HSC subsets.

Disclosure of potential conflicts of interest is found at the end of this article.