Labeling of mesenchymal stromal cells with iron oxide–poly(l-lactide) nanoparticles for magnetic resonance imaging: uptake, persistence, effects on cellular function and magnetic resonance imaging properties

Abstract

Background aims. Mesenchymal stromal cells (MSC) are the focus of research in regenerative medicine aiming at the regulatory approval of these cells for specific indications. To cope with the regulatory requirements for somatic cell therapy, novel approaches that do not interfere with the natural behavior of the cells are necessary. In this context in vivo magnetic resonance imaging (MRI) of labeled MSC could be an appropriate tool. Cell labeling for MRI with a variety of different iron oxide preparations is frequently published. However, most publications lack a comprehensive assessment of the noninterference of the contrast agent with the functionality of the labeled MSC, which is a prerequisite for the validity of cell-tracking via MRI. Methods.We studied the effects of iron oxide-poly(L-lactide) nanoparticles in MSC with flow cytom-etry, transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), Prussian blue staining, CyQuant® proliferation testing, colony-forming unit-fibroblast (CFU-F) assays, flow chamber adhesion testing, immuno-logic tests and differentiation tests. Furthermore iron-labeled MSC were studied by MRI in agarose phantoms and Wistar rats. Results. It could be demonstrated that MSC show rapid uptake of nanoparticles and long-lasting intracellular persistence in the endosomal compartment. Labeling of the MSC with these particles has no influence on viability, differentiation, clonogenicity, proliferation, adhesion, phenotype and immunosuppressive properties. They show excellent MRI properties in agarose phantoms and after subcutaneous implantation in rats over several weeks. Conclusions. These particles qualify for studying MSC homing and trafficking via MRI.

GFP Labeling and Hepatic Differentiation Potential of Human Placenta-Derived Mesenchymal Stem Cells

“…This results from the difficulty in tracking mesenchymal stem cells (MSCs) after transplantation due to the lack of reliable MSC-specific markers in vivo. Nowadays, MSCs can be stably labeled or stained in vivo using numerous new methods involving 5-bromo-2'-deoxyuridine (BrdU), magnetic nanoparticles, 18-fludeoxyglucose (18FDG) and green fluorescent protein (GFP) [5][6][7][8][9].…”

In-vitro Labelling of Ovine Adipose-Derived Mesenchymal Stem Cells (oADMSCs) and Tracking Using MRI Technique

“…A similar finding was observed with Prussian blue staining in MIRB labelled human MSCs, human cervical carcinoma (HeLa) cells and CG-4 cells (15). The effects of iron oxide-poly (L-lactide) nanoparticles was studied in human BM-MSCs (15); in Cynomolgus monkey BMMSCs labeled with MIRB (8, 10); in rat BM-MSCs (16); in human neural progenitor cells labeled with MIRB (1,12).…”

Nanoparticles and their potential for application in bone

“…With respect to bone cells, and particularly MSCs, the particles ideally should not compromise the differentiation potential. In vitro analyses of MSC differentiation capacity in the presence of nanoparticles demonstrated the innocuousness of several SPIO nanoparticles, [29][30][31]33 as well as of certain gold nanoparticles 28 that were optimized for efficient MSC labeling and MRI visualization. As the MSC differentiation potential in vitro does not necessarily correlate with the in vivo situation, a study investigating the stemness of MSCs exposed to SPIO nanoparticles went one step further by verifying the differentiation capacity in vivo based on ossicle formation by labeled human MSCs in immunocompromised mice.…”

“…36,38 With regard to clinical application, various SPIO nanoparticles were applied subcutaneously in mice, eg, via the incorporation of labeled MSCs in collagen scaffolds, and were demonstrated to be suitable for efficient in vivo long-term labeling and for producing convincing visualization by MRI. 30,31 However, one has to keep in mind that with this technique, primarily the particles themselves are tracked and not the cells.…”

“…[21][22][23][24] To monitor these processes, MSCs have been labeled with diverse nanoparticles, such as quantum dots, which are small semiconductor nanocrystals, 25,26 fluorescence-labeled mesoporous silica nanoparticles, 27 gold nanoparticles, 28 or superparamagnetic iron oxide (SPIO) nanoparticles. [29][30][31] Several types of SPIO nanoparticles have already been clinically approved for use as contrast agents in MRI, eg, of bowel or liver. 32 It should be noted that bone represents a formidable target organ, which poses a particular challenge with regard to cell labeling, due to its high mineralization grade, making the visualization of labeled cells in MRI difficult.…”