The use of microgel iron oxide nanoparticles in studies of magnetic resonance relaxation and endothelial progenitor cell labelling
ABSTRACT In vivo tracking of stem cells after transplantation is crucial for understanding cell-fate and therapeutic efficacy. By labelling stem cells with magnetic particles, they can be tracked by Magnetic Resonance Imaging (MRI). We previously demonstrated that microgel iron oxide nanoparticle (MGIO) provide superior tracking sensitivity over commercially available particles. Here, we describe the synthesis of MGIO and report on their morphology, hydrodynamic diameters (87-766 nm), iron oxide weight content (up to 82%) and magnetization characteristics (M(s)=52.9 Am(2)/kg, M(R)=0.061 Am(2)/kg and H(c)=0.672 A/m). Their MR relaxation characteristics are comparable to those of theoretical models and represent the first such correlation between model and real particles of varying diameters. A labelling study of primary endothelial progenitor cells also confirms that MGIO is an efficient label regardless of cell type. The facile synthesis of MGIO makes it a useful tool for the studying of relaxation induced by magnetic particles and cellular tracking by MRI.
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ABSTRACT: In the present study, quantum dot (QD) capped magnetite nanorings (NRs) with a high luminescence and magnetic vortex core have been successfully developed as a new class of magnetic-fluorescent nanoprobe. Through electrostatic interaction, cationic polyethylenimine (PEI) capped QD have been firmly graft into negatively charged magnetite NRs modified with citric acid on the surface. The obtained biocompatible multicolor QD capped magnetite NRs exhibit a much stronger magnetic resonance (MR) T2* effect where the r2* relaxivity and r2*/r1 ratio are 4 times and 110 times respectively larger than those of a commercial superparamagnetic iron oxide. The multiphoton fluorescence imaging and cell uptake of QD capped magnetite NRs are also demonstrated using MGH bladder cancer cells. In particular, these QD capped magnetite NRs can escape from endosomes and be released into the cytoplasm. The obtained results from these exploratory experiments suggest that the cell-penetrating QD capped magnetite NRs could be an excellent dual-modality nanoprobe for intracellular imaging and therapeutic applications. This work has shown great potential of the magnetic vortex core based multifunctional nanoparticle as a high performance nanoprobe for biomedical applications.Journal of the American Chemical Society 09/2010; 132(42):14803-11. DOI:10.1021/ja103738t · 11.44 Impact Factor
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ABSTRACT: After four decades of study, the biological role of fetal microchimerism (FMC) remains elusive. Transfer of fetal cells to the mother begins soon after implantation, and increases with gestational age. FMC cells then decline after delivery, but remain detectable for years post-partum. These cells have been implicated in rheumatoid arthritis remission during pregnancy and the prevention of breast cancer by graft-versus-tumor-effects. However, any beneficial effects contrast with their suspected malevolence in triggering of systemic sclerosis after childrearing or their stromal support for tumor formation. Recent evidence that FMC cells participate in disease and tissue repair has stirred controversy on their origin. The detection of FMC cells during early embryogenesis together with the diversity of hematopoietic, mesenchymal and endothelial markers, and plasticity of morphology when integrated into various tissues, provides evidence for their stemness. However, proof of their phenotype in conventional stem cell differentiation assays has been beset with difficulty in isolating and expanding them in culture. Unraveling the function of FMC cells will provide insight into both their engagement in disease and their therapeutic potential.Molecular Human Reproduction 11/2010; 16(11):869-78. DOI:10.1093/molehr/gaq067 · 3.48 Impact Factor
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ABSTRACT: Stem cells transplantation is a promising therapy for numerous diseases where transplanted cells repair or replace damaged host tissue. While their efficacy and optimal delivery is under intense investigation, there lies a pivotal question seeking the whereabouts of the cells after transplantation. Imaging techniques have emerged in recent years, both to enable monitoring of stem cell location in patients and to improve the reliability of animal experimentation. Magnetic resonance imaging (MRI) allows tracking of stem cells tagged with magnetic nanoparticle labels prior to transplantation, but is restricted by the inability of stem cells to incorporate sufficient label. This review addresses the optimisation of stem cell tagging with iron oxide particles to improve MR tracking, alternative cell labelling techniques using gene transfer, and the translational applications of cellular imaging. KeywordsMagnetic nanoparticle-Stem cell tracking-MRI-SPIO12/2010: pages 459-485;