Detection of magnetically labelled embryonic stem cells in the rat brain by high resolution MR-Imaging in vivo

C. Sieland; A. Stroh; C. Faber; T. Neuberger; K. Weir; K. Hild; S. Mueller; P. Lorenz; T. Grune; P. Jakob; M. Taupitz; H. Pilgrimm; J. Schnorr; C. Zimmer

doi:10.1055/s-2005-864008

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, Inhaltsverzeichnis

Detection of magnetically labelled embryonic stem cells in the rat brain by high resolution MR-Imaging in vivo

C Sieland ¹, A Stroh ¹, C Faber ², T Neuberger ², K Weir ¹, K Hild ¹, S Mueller ¹, P Lorenz ³, T Grune ⁴, P Jakob ², M Taupitz ¹, H Pilgrimm ⁵, J Schnorr ¹, C Zimmer ⁶

¹Institute of Radiology
²Institute of Physics, EP5, University of Würzburg, Germany
³Institute of Pharmacology and Toxicology; Charité University Hospital, Berlin, Germany
⁴Institute for Environmental Medical Research (IUF), Düsseldorf, Germany
⁵Ferropharm GmbH, Teltow, Germany
⁶Department of Neuroradiology; University Hospital Leipzig, Germany

Abstract

Objectives: Stem cell transplantation is a promising approach in the therapy of Parkinson's Disease (PD). We used high resoltution MRI together with an effective magnetic labelling to asses the detection limit, localisation and migration of transplanted embryonic stem cells in a rat model of PD. Additionally the influence of the magnetic label on the biology of the cells was investigated.

Materials and Methods: Murine embryonic stem cells were magnetically labelled in vitro with Very Small Super-Paramagnetic Iron-Oxide-Particles (VSOP). The lipofection agent FuGENE was added in different concentrations during incubation with VSOP. The incubation time was varied between 1.5 and 24 hours. The level of oxidative stress was detected by measuring the level of malonyldialdehyde (MDA) and protein carbonyls. Different numbers (1000, 100, 20) of magnetically labelled cells were transplanted the striatum of healthy rats and highest field MRI at 17.5 T was conducted. For the assesment of cell migartion and localisation MRI at 7T was performed after transplantation of 1×10⁵ magnetically labelled cells into the striatum of 6-OHDA lesioned rats.

Results: Incubation of embryonic stem cells with VSOP leads to a highly significant uptake of iron. Coincubation with FuGENE for 4 hours further increased intracellular VSOP concentration. However the incubation of cells with iron-oxide-particles also results in a transient augmentation of oxidative stress. The MRI detection limit in vivo at 17.5 T ranges below 100 transplanted ESC. After transplantation of ESC in the rat model of PD at 7T characteristic signal extinctions in T2* weighted images were observed. Eight weeks after transplantation the hypointense signal shows a much more widespread distribution around the transplantation site. Between the transplanted animals very heterogenous spatial distributions and dynamics was observed.

Conclusion: Magnetic labelling of embryonic stem cells is a feasible tool for the monitoring of cell-based therapies. Even if the labelling does increase cellular stress the long term survival is not significantly affected. The number of detectable cells of less than 100 gives new possibilities for cellular MRI. Cell migration has shown to be an important issue concerning transplantation in PD.