Stem cell tracking in cellular therapy and regenerative medicine is an urgent need, superparamagnetic iron oxide nanoparticles (IONPs) could be used as contrast agents in magnetic resonance imaging (MRI) that allows visualization of the implanted cells ensuring they reach the desired sites in vivo. Herein, we report the study of the interaction of 3,4-dihydroxyhydrocinnamic acid (DHCA) functionalized IONPs that have desirable properties for T2 - weighted MRI, with bone marrow-derived primary human mesenchymal stem cells (hMSCs). Using the multiparametric high-content imaging method, we evaluate cell viability, formation of reactive oxygen species, mitochondrial health, as well as cell morphology and determine that the hMSCs are minimally affected after labelling with IONPs. Their cellular uptake is visualized by transmission electron microscopy (TEM) and Prussian Blue staining, and quantified using an iron specific colourimetric method. In vitro and in vivo studies demonstrate that these IONPs are biocompatible and can produce significant contrast enhancement in T2-weighted MRI. Iron oxide nanoparticles are detected in vivo as hypointense regions in the liver up to two weeks post injection using 9.4 T MRI. These DHCA functionalized IONPs are promising contrast agents for stem cell tracking by T2-weighted MRI as they are biocompatible and show no evidence of cytotoxic effects on hMSCs.

Synthesis of finely size-tuned β-FeOOH nanoellipsoids which could be used as precursors to form anisotropic iron oxide nanoparticles by reduction.

Lipids are a major source of energy for most tissues, and lipid uptake and storage is therefore crucial for energy homeostasis. So far, quantification of lipid uptake in vivo has primarily relied on radioactive isotope labeling, exposing human subjects or experimental animals to ionizing radiation. Here, we describe the quantification of in vivo uptake of chylomicrons, the primary carriers of dietary lipids, in metabolically active tissues using magnetic particle imaging (MPI) and magnetic particle spectroscopy (MPS). We show that loading artificial chylomicrons (ACM) with iron oxide nanoparticles (IONPs) enables rapid and highly sensitive post hoc detection of lipid uptake in situ using MPS. Importantly, by utilizing highly magnetic Zn-doped iron oxide nanoparticles (ZnMNPs), we generated ACM with MPI tracer properties superseding the current gold-standard, Resovist®, enabling quantification of lipid uptake from whole-animal scans. We focused on brown adipose tissue (BAT), which dissipates heat and can consume a large part of nutrient lipids, as a model for tightly regulated and inducible lipid uptake. High BAT activity in humans correlates with leanness and improved cardiometabolic health. However, the lack of non-radioactive imaging techniques is an important hurdle for the development of BAT-centered therapies for metabolic diseases such as obesity and type 2 diabetes. Comparison of MPI measurements with iron quantification by inductively coupled plasma mass spectrometry (ICP-MS) revealed that MPI rivals the performance of this highly sensitive technique. Our results represent radioactivity-free quantification of lipid uptake in metabolically active tissues like BAT. KEYWORDS magnetic particle imaging, brown adipose tissue, BAT, chylomicron, TRL, magnetic particle spectroscopy, lipid uptake Adipose tissues are the major sites of lipid storage. There are two major types of adipose tissue, white adipose tissue (WAT) and BAT. 1 BAT is an organ that is capable of converting chemical energy into heat by mitochondrial uncoupling. 2,3 Since the discovery of metabolically active BAT in adult humans in 2007/9, 4-8 it has been the subject of intense research due to the possibility of exploiting its thermogenic properties for combating obesity, diabetes, dyslipidemia, and cardiovascular disease. [9][10][11] During the process of thermogenesis in BAT, there is a dramatic increase in the demand for energy substrates and ca. 50-75% of the food-derived lipids and glucose, respectively, are taken up by activated BAT. [12][13][14][15][16] Consequently, quantification of lipid uptake in BAT is a highly valuable tool both to measure BAT activity, as well as to develop ways to measure lipid transport and storage. Additionally, safe and non-invasive measurements of BAT activity in humans would be an important prerequisite for the development of antiobesity drugs.Lipoprotein particles are composed of triglycerides, phospholipids, and cholesterol, and are associated with apolipoproteins (ApoA, ApoB, ApoC, and ApoE), which confer fu...

Magnetic nanoparticles (NPs) are powerful agents to induce hyperthermia in tumours upon the application of an alternating magnetic field or an infrared laser. Dopants have been investigated to alter different...

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