http://www.mdpi.com/journal/ijms/special_issues/magnetic-nanoparticles-ijms/ Dear Colleagues, Magnetic micro- and nanoparticles have been used in biological and biomedical investigations since the 1920s when Heilbrunn and Seifritz first used the forces on these particles to examine the rheological properties of cells. Since that time, myriad uses for these particles have arisen and much progress has been made in synthesis techniques and bio-functionalization. Superparamagnetic iron oxides are routinely used in the clinic today as MRI contrast agents and are found in many pathology laboratories around the world where they are used to tag cells for cell separation and immunoassay. More recent, novel uses include binding to specific cell receptors to control cell function and stem cell differentiation for tissue engineering and regenerative medicine, as well as magnetic targeting for drug and gene delivery and magnetic fluid hyperthermia. This issue will cover a variety of topics related to the use of MNPs in biomedicine and examine both novel synthesis and functionalization techniques as well as their current and future uses in biomedical research, diagnostics and therapy. Prof. Dr. Jon Dobson Guest Editor Related Special Issue Magnetic Nanoparticles in Materials. {snippet name="submission_info"} http://www.mdpi.com/1422-0067/12/1/12/ Superparamagnetic iron-oxide particles (SPIO) are used in different ways as contrast agents for magnetic resonance imaging (MRI): Particles with high nonspecific uptake are required for unspecific labeling of phagocytic cells whereas those that target specific molecules need to have very low unspecific cellular uptake. We compared iron-oxide particles with different core materials (magnetite, maghemite), different coatings (none, dextran, carboxydextran, polystyrene) and different hydrodynamic diameters (20–850 nm) for internalization kinetics, release of internalized particles, toxicity, localization of particles and ability to generate contrast in MRI. Particle uptake was investigated with U118 glioma cells und human umbilical vein endothelial cells (HUVEC), which exhibit different phagocytic properties. In both cell types, the contrast agents Resovist, B102, non-coated Fe3O4 particles and microspheres were better internalized than dextran-coated Nanomag particles. SPIO uptake into the cells increased with particle/iron concentrations. Maximum intracellular accumulation of iron particles was observed between 24 h to 36 h of exposure. Most particles were retained in the cells for at least two weeks, were deeply internalized, and only few remained adsorbed at the cell surface. Internalized particles clustered in the cytosol of the cells. Furthermore, all particles showed a low toxicity. By MRI, monolayers consisting of 5000 Resovist-labeled cells could easily be visualized. Thus, for unspecific cell labeling, Resovist and microspheres show the highest potential, whereas Nanomag particles are promising contrast agents for target-specific labeling. http://www.mdpi.com/1422-0067/12/1/12/ Thu, 23 Dec 2010 00:00:00 CET International Journal of Molecular Sciences 2010-12-23 12 1 Article 12 23 1422-0067 Biological Properties of Iron Oxide Nanoparticles for Cellular and Molecular Magnetic Resonance Imaging 2010-12-23 doi: 10.3390/ijms12010012 Thomas Schlorf Manuela Meincke Elke Kossel Claus-Christian Glüer Olav Jansen Rolf Mentlein http://www.mdpi.com/1422-0067/11/8/2910/ Here we applied a magnetic force-based tissue engineering technique to cardiac tissue fabrication. A mixture of extracellular matrix precursor and cardiomyocytes labeled with magnetic nanoparticles was added into a well containing a central polycarbonate cylinder. With the use of a magnet, the cells were attracted to the bottom of the well and allowed to form a cell layer. During cultivation, the cell layer shrank towards the cylinder, leading to the formation of a ring-shaped tissue that possessed a multilayered cell structure and contractile properties. These results indicate that magnetic tissue fabrication is a promising approach for cardiac tissue engineering. http://www.mdpi.com/1422-0067/11/8/2910/ Tue, 10 Aug 2010 00:00:00 CEST International Journal of Molecular Sciences 2010-08-10 11 8 Article 2910 2920 1422-0067 Construction of Cardiac Tissue Rings Using a Magnetic Tissue Fabrication Technique 2010-08-10 doi: 10.3390/ijms11082910 Hirokazu Akiyama Akira Ito Masanori Sato Yoshinori Kawabe Masamichi Kamihira http://www.mdpi.com/1422-0067/11/4/1759/ In this review we discuss the development of paramagnetic liposomes incorporating MRI contrast agents and show how these are utilized in cellular imaging in vitro. Bi-functional, bi-modal imaging paramagnetic liposome systems are also described. Next we discuss the upgrading of paramagnetic liposomes into bi-modal imaging neutral nanoparticles for in vivo imaging applications. We discuss the development of such systems and show how paramagnetic liposomes and imaging nanoparticles could be developed as platforms for future multi-functional, multi-modal imaging theranostic nanodevices tailor-made for the combined imaging of early stage disease pathology and functional drug delivery. http://www.mdpi.com/1422-0067/11/4/1759/ Thu, 15 Apr 2010 00:00:00 CEST International Journal of Molecular Sciences 2010-04-15 11 4 Review 1759 1776 1422-0067 Paramagnetic Liposome Nanoparticles for Cellular and Tumour Imaging 2010-04-15 doi: 10.3390/ijms11041759 Kamaly Miller http://www.mdpi.com/1422-0067/11/3/1070/ Advances in stem cell research have provided important understanding of the cell biology and offered great promise for developing new strategies for tissue regeneration. The beneficial effects of stem cell therapy depend also by the development of new approachs for the track of stem cells in living subjects over time after transplantation. Recent developments in the use of nanotechnologies have contributed to advance of the high-resolution in vivo imaging methods, including positron emission tomography (PET), single-photon emission tomography (SPECT), magnetic resonance (MR) imaging, and X-Ray computed microtomography (microCT). This review examines the use of nanotechnologies for stem cell tracking. http://www.mdpi.com/1422-0067/11/3/1070/ Fri, 12 Mar 2010 00:00:00 CET International Journal of Molecular Sciences 2010-03-12 11 3 Review 1070 1081 1422-0067 Stem Cell Tracking by Nanotechnologies 2010-03-12 doi: 10.3390/ijms11031070 Villa Erratico Razini Fiori Rustichelli Torrente Belicchi http://www.mdpi.com/1422-0067/11/3/967/ Magnetic nanoparticles (MNPs) are important contrast agents used to monitor a range of neuropathological processes; microglial cells significantly contribute to MNP uptake in sites of pathology. Microglial activation occurs following most CNS pathologies but it is not known if such activation alters MNP uptake, intracellular processing and toxicity. We assessed these parameters in microglial cultures with and without experimental ‘activation’. Microglia showed rapid and extensive MNP uptake under basal conditions with no changes found following activation; significant microglial toxicity was observed at higher particle concentrations. Based on our findings, we suggest that avid MNP uptake by endogenous CNS microglia could significantly limit uptake by other cellular subtypes in mixed neural cell populations. http://www.mdpi.com/1422-0067/11/3/967/ Mon, 08 Mar 2010 00:00:00 CET International Journal of Molecular Sciences 2010-03-08 11 3 Communication 967 981 1422-0067 Robust Uptake of Magnetic Nanoparticles (MNPs) by Central Nervous System (CNS) Microglia: Implications for Particle Uptake in Mixed Neural Cell Populations 2010-03-08 doi: 10.3390/ijms11030967 Mark R. Pickard Divya M. Chari