In-Vivo Positive Contrast Tracking of Bone Marrow Stem Cells Labeled with IODEX-TAT-FITC Nanoparticles

Introduction Bone marrow-derived mesenchymal stem cells (BMSCs) possess tremendous therapeutic potential because of their capacity to differentiate into multiple functional lineages. To assess the efficacy of BMSCs cell therapy, MRI methods are being developed to monitor their bio-distribution in longitudinal studies. Although, labeling BMSCs with iron-oxide nanoparticles can facilitate their in vivo detection, cellular function and mobility might be compromised due to toxicity. TAT-peptide derivatized ultra-small super-paramagnetic iron oxide nanoparticles coated with dextran (IODEX-TAT-FITC) have demonstrated their potential for BMSCs labeling without detrimental effects on cell viability or function [1]. In order to increase the detection limits, the susceptibility effect of the iron cores can be exploited to enhance sensitivity.. However precision in negative contrast detection could be reduced by partial volume effects and local magnetic field inhomogeneities. Positive contrast offers a more practical detection scheme with high contrast-to-noise ratio [2]. In this study, we explore the suitability of positive contrast MRI for in vivo tracking of labeled BMSCs.