A Safe and Effective Magnetic Labeling Protocol for MRI-Based Tracking of Human Adult Neural Stem Cells.

Albrecht Stroh,Antje Y Dreyer,Wenke Fröhlich,Jenny Kressel,Roland Coras,Annette Förschler,Ingmar Blümcke,Donald Lobsien,Saida Zoubaa,Jürgen Schlegel,Johannes Boltze,Claus Zimmer

doi:10.3389/fnins.2019.01092

Abstract

Magnetic resonance imaging (MRI) provides a unique tool for in vivo visualization and tracking of stem cells in the brain. This is of particular importance when assessing safety of experimental cell treatments in the preclinical or clinical setup. Yet, specific imaging requires an efficient and non-perturbing cellular magnetic labeling which precludes adverse effects of the tag, e.g., the impact of iron-oxide-nanoparticles on the critical differentiation and integration processes of the respective stem cell population investigated. In this study we investigated the effects of very small superparamagnetic iron oxide particle (VSOP) labeling on viability, stemness, and neuronal differentiation potential of primary human adult neural stem cells (haNSCs). Cytoplasmic VSOP incorporation massively reduced the transverse relaxation time T2, an important parameter determining MR contrast. Cells retained cytoplasmic label for at least a month, indicating stable incorporation, a necessity for long-term imaging. Using a clinical 3T MRI, 1 × 103 haNSCs were visualized upon injection in a gel phantom, but detection limit was much lower (5 × 104 cells) in layer phantoms and using an imaging protocol feasible in a clinical scenario. Transcriptional analysis and fluorescence immunocytochemistry did not reveal a detrimental impact of VSOP labeling on important parameters of cellular physiology with cellular viability, stemness and neuronal differentiation potential remaining unaffected. This represents a pivotal prerequisite with respect to clinical application of this method.

Highlights

Stem cell transplantation represents one of the most promising strategies for the restoration of lost cells or tissue including their functions, or at least for delaying the pathogenic progress in neurodegenerative diseases (Janowski et al, 2015)
We were able to show that labeling of human adult neural stem cells (haNSCs) with iron-oxide-particles, required for a high-resolution MR Imaging, is both safe and efficient
The protocol settings were chosen on optimal detectability in very small superparamagnetic iron oxide particles (VSOP)-labeled mesenchymal stem cells (Stroh et al, 2011)

Summary

Introduction

Stem cell transplantation represents one of the most promising strategies for the restoration of lost cells or tissue including their functions, or at least for delaying the pathogenic progress in neurodegenerative diseases (Janowski et al, 2015). Adult neural stem cells are present in the subventricular zone and in the subgranular zone of the hippocampal dentate gyrus (Zimmer et al, 1995; Stroh et al, 2005, 2009). These cells can be isolated from patients with intractable temporal lobe epilepsy subjected to neurosurgical intervention (Hoehn et al, 2002). Citrate-coated very small superparamagnetic iron oxide particles (VSOP) are widely used for pretransplantation stem cell labeling These particles are incorporated via endocytosis, aggregate and get stored in intracytoplasmic vesicles (Zimmer et al, 1995; Stroh et al, 2005). Superparamagnetic iron oxide particles seem to be biodegradable (Weissleder et al, 1989) and can even be utilized by the cells in iron metabolism pathways (Pouliquen et al, 1991)

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Results

Conclusion