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This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 2007-0251v1 2007-0251v2 26/2/505    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 Google Scholar Articles by Neri, M. Articles by Gritti, A. PubMed PubMed Citation Articles by Neri, M. Articles by Gritti, A.

TECHNOLOGY DEVELOPMENT

Efficient In Vitro Labeling of Human Neural Precursor Cells with Superparamagnetic Iron Oxide Particles: Relevance for In Vivo Cell Tracking

^aStem Cell Research Institute and
^bNeuroradiology Department, San Raffaele Scientific Institute, Milan, Italy;
^cDepartment of Morphology and Biomedical Sciences, Section of Anatomy, University of Verona, Verona, Italy;
^dDepartment Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy

Key Words. Human neural precursor cells • Magnetic resonance imaging • Superparamagnetic iron oxide • Cell tracking Transplantation

Correspondence: Angela Gritti, Ph.D., San Raffaele Scientific Institute, San Raffaele Telethon Institute for Gene Therapy, Via Olgettina 58, 20132 Milano, Italy. Telephone: 39-02-2643-4623; Fax: 39-02-2643-4668; e-mail: gritti.angela{at}hsr.it; or Angelo Vescovi, Ph.D., Department Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy. Telephone: 39-02-6448-3351; Fax: 39-02-7004-31033; e-mail: vescovi{at}tin.it

Received April 4, 2007; accepted for publication October 14, 2007.
First published online in STEM CELLS EXPRESS   November 1, 2007.



Recent studies have raised appealing possibilities of replacing damaged or lost neural cells by transplanting in vitro-expanded neural precursor cells (NPCs) and/or their progeny. Magnetic resonance (MR) tracking of superparamagnetic iron oxide (SPIO)-labeled cells is a noninvasive technique to track transplanted cells in longitudinal studies on living animals. Murine NPCs and human mesenchymal or hematopoietic stem cells can be efficiently labeled by SPIOs. However, the validation of SPIO-based protocols to label human neural precursor cells (hNPCs) has not been extensively addressed. Here, we report the development and validation of optimized protocols using two SPIOs (Sinerem and Endorem) to label human hNPCs that display bona fide stem cell features in vitro. A careful titration of both SPIOs was required to set the conditions resulting in efficient cell labeling without impairment of cell survival, proliferation, self-renewal, and multipotency. In vivo magnetic resonance imaging (MRI) combined with histology and confocal microscopy indicated that low numbers (5 x 10³ to 1 x 10⁴) of viable SPIO-labeled hNPCs could be efficiently detected in the short term after transplantation in the adult murine brain and could be tracked for at least 1 month in longitudinal studies. By using this approach, we also clarified the impact of donor cell death to the MR signal. This study describes a simple protocol to label NPCs of human origin using SPIOs at optimized low dosages and demonstrates the feasibility of noninvasive imaging of labeled cells after transplantation in the brain; it also evidentiates potential limitations of the technique that have to be considered, particularly in the perspective of neural cell-based clinical applications.

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