BRIEF ARTICLE Labeling Human Mesenchymal Stem Cells with Fluorescent Contrast Agents: the Biological Impact

Purpose: This study aims to determine the effect of human mesenchymal stem cell (hMSC) labeling with the fluorescent dye DiD and the iron oxide nanoparticle ferucarbotran on chondrogenesis. Procedures: hMSCs were labeled with DiD alone or with DiD and ferucarbotran (DiD/ ferucarbotran). hMSCs underwent confocal microscopy, optical imaging (OI), and magnetic resonance (MR) imaging. Chondrogenesis was induced by transforming growth factor-b and confirmed by histopathology and glycosaminoglycan (GAG) production. Data of labeled and unlabeled hMSCs were compared with a t test. Results: Cellular uptake of DiD and ferucarbotran was confirmed with confocal microscopy. DiD labeling caused a significant fluorescence on OI, and ferucarbotran labeling caused a significant T2 * effect on MR images. Compared to nonlabeled controls, progenies of labeled MSCs exhibited similar chondrocyte morphology after chondrogenic differentiation, but the labeled cells demonstrated significantly reduced GAG production (pG0.05). Conclusion: DiD and DiD/ferucarbotran labeling of hMSC does not interfere with cell viability or morphologic differentiation into chondrocytes, but labeled cells exhibit significantly less GAG production compared to unlabeled cells