Abstract
BackgroundTherapy with mesenchymal stem cells (MSCs) has been reported to provide beneficial effects in the treatment of neurological and orthopaedic disorders in dogs. The exact mechanism of action is poorly understood. Magnetic resonance imaging (MRI) gives the opportunity to observe MSCs after clinical administration. To visualise MSCs with the help of MRI, labelling with an MRI contrast agent is necessary. However, it must be clarified whether there is any negative influence on cell function and viability after labelling prior to clinical administration.ResultsFor the purpose of the study, seven samples with canine adipose-derived stem cells were incubated with superparamagnetic iron oxide nanoparticles (SPIO: 319.2 μg/mL Fe) for 24 h. The internalisation of the iron particles occurred via endocytosis. SPIO particles were localized as free clusters in the cytoplasm or within lysosomes depending on the time of investigation. The efficiency of the labelling was investigated using Prussian blue staining and MACS assay. After 3 weeks the percentage of SPIO labelled canine stem cells decreased. Phalloidin staining showed no negative effect on the cytoskeleton. Labelled cells underwent osteogenic and adipogenic differentiation. Chondrogenic differentiation occurred to a lesser extent compared with a control sample. MTT-Test and wound healing assay showed no influence of labelling on the proliferation. The duration of SPIO labelling was assessed using a 1 Tesla clinical MRI scanner and T2 weighted turbo spin echo and T2 weighted gradient echo MRI sequences 1, 2 and 3 weeks after labelling. The hypointensity caused by SPIO lasted for 3 weeks in both sequences.ConclusionsAn Endorem labelling concentration of 319.2 μg/mL Fe (448 μg/mL SPIO) had no adverse effects on the viability of canine ASCs. Therefore, this contrast agent could be used as a model for iron oxide labelling agents. However, the tracking ability in vivo has to be evaluated in further studies.
Highlights
Therapy with mesenchymal stem cells (MSCs) has been reported to provide beneficial effects in the treatment of neurological and orthopaedic disorders in dogs
Isolation of canine mesenchymal stem cells MSCs were isolated as previously reported [22] from intraabdominal or subcutaneous adipose tissue that was harvested from seven dogs during routine surgical procedures
Isolation of adipose-derived canine stem cells (ASCs) and efficiency of Endorem labelling in the Prussian blue staining and Magnetic activated cell sorting (MACS) assay ASCs could be isolated from canine adipose tissue
Summary
Therapy with mesenchymal stem cells (MSCs) has been reported to provide beneficial effects in the treatment of neurological and orthopaedic disorders in dogs. Magnetic resonance imaging (MRI) gives the opportunity to observe MSCs after clinical administration. To visualise MSCs with the help of MRI, labelling with an MRI contrast agent is necessary. It must be clarified whether there is any negative influence on cell function and viability after labelling prior to clinical administration. There is still little information about the exact mechanism of action of MSCs. The behaviour of the MSCs during the stem cell therapy can be examined non-invasively by magnetic resonance imaging (MRI). A commercially available MRI contrast agent that contains a dextran coated SPIO formulation—ferrumoxides—is known under the name Endorem (Guerbet). Endorem affects the T2 relaxation time by inducing a strong field inhomogeneity, leading to a signal decrease as a result of the susceptibility changes in the tissues containing Endorem
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