Ultrastructural characterization of mesenchymal stromal cells labeled with ultrasmall superparamagnetic iron-oxide nanoparticles for clinical tracking studies

• Published in: Scandinavian journal of clinical and laboratory investigation Vol. 74; no. 5; pp. 437 - 446
• Main Authors: Hansen, Louise, Hansen, Alastair B., Mathiasen, Anders B., Ng, Michael, Bhakoo, Kishore, Ekblond, Annette, Kastrup, Jens, Friis, Tina
• Format: Journal Article
• Language: English
• Published: England Informa Healthcare 01.08.2014; Taylor & Francis
• Subjects: Cell Proliferation; Cell Survival; Cell Tracking - methods; Cells, Cultured; Dextrans - chemistry; Dextrans - toxicity; Electron microscopy; Flow Cytometry; Humans; labeling; Magnetite Nanoparticles - chemistry; Magnetite Nanoparticles - toxicity; Mesenchymal Stromal Cells - ultrastructure; MSC; SPIO; Staining and Labeling; stem cells; toxicity; ultrastructure; USPIO; toxicity; stem cells; SPIO; labeling; Electron microscopy; MSC; USPIO; ultrastructure
• ISSN: 0036-5513; 1502-7686
• DOI: 10.3109/00365513.2014.900698

Abstract Introduction. To evaluate survival and engraftment of mesenchymal stromal cells (MSCs) in vivo, it is necessary to track implanted cells non-invasively with a method, which does not influence cellular ultrastructure and functional characteristics. Iron-oxide particles have been applied for cell tracking for years, but knowledge regarding possible cytotoxic ultrastructural changes subsequent to iron-oxide particle labeling is limited. Hence, the purpose of this study was to label MSCs with dextran-coated ultrasmall super-paramagnetic iron-oxide (USPIO) particles conjugated with the transduction sequence of trans-activator of transcription (TAT) (IODEX-TAT) and evaluate the effect of labeling on ultrastructure, viability, phenotype and proliferative capacity of the cells. Materials and methods. MSCs were labeled with 5 and 10 μg IODEX-TAT/105 cells for 2, 6 and 21 hours. IODEX-TAT uptake and cellular ultrastructure were determined by electron microscopy. Cell viability was determined by propidium iodide staining and cell proliferation capacity by 5-bromo-2-deoxyuridine (BrdU) incorporation. Maintenance of stem cell surface markers was determined by flow cytometry. Results. IODEX-TAT labeling for 2, 6 and 21 h did not influence cellular ultrastructure or viability. Moreover, neither stem cell surface markers nor cell proliferation capacity was affected by labeling with IODEX-TAT. Conclusion. Our results demonstrate that labeling of MSCs for 21 h with a clinically relevant dose of 10 μg IODEX-TAT/105 cells is feasible and does not affect MSC ultrastructure, viability, phenotype or proliferation capacity.