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The use of multimodal contrast agents can potentially overcome the intrinsic limitations of individual imaging methods. We have validated synthetic antiferromagnetic nanoparticles (SAF-NPs) as bimodal contrast agents for in vitro cell labeling and in vivo cell tracking using magnetic resonance imaging (MRI) and computed tomography (CT). SAF-NP-labeled cells showed high contrast in MRI phantom studies (r(2)* = 712 s(-1) mM(-1)), while pelleted cells showed clear contrast enhancement in CT. After intravenous SAF-NP injection, nanoparticles accumulated in the liver and spleen, as visualized in vivo by significant MRI contrast enhancement. Intravenous injection of SAF-NP-labeled cells resulted in cell accumulation in the lungs, which was clearly detectable by using CT but not by using MRI. SAF-NPs proved to be very efficient cell labeling agents for complementary MRI- and CT-based cell tracking. Bimodal monitoring of SAF-NP labeled cells is in particular of interest for applications where the applied imaging methods are not able to visualize the particles and/or cells in all organs. agency for Innovation by Science and Technology IWT 080017 IWT 140061 European Commission European Commission Joint Research Centre H2020_FET-OPEN-766456 H2020-NMP-2015-686009 FP7-NMP-2008-228933

Funding: This research was funded by the Flemish foundation for Innovation, Science and Technology for the IWT SBO ‘Imagine’ (080017) and IWT SBO ‘NanoCoMIT’ (140061), the European Commission under the ‘PANA’ project, Call H2020-NMP-2015-two-stage (grant 686009), and by the University of Leuven for program financing PF IMIR (10/017). Acknowledgments: We are grateful for technical assistance by Jesse Trekker (IMEC, KULeuven) for particle characterization, Marc Jans (Lab of Histology, UHasselt) for ex vivo TEM measurement, Tom Dresselaers (Biomedical MRI, KULeuven) for help with MRI experiments and Joris Deconinck (IMEC) for ICP-OES experiments is highly appreciated. We would also like to thank Visualsonics for their guidance and help with photoacoustic imaging experimentation. This research was funded by the Flemish foundation for Innovation, Science and Technology for the IWT SBO 'Imagine' (080017) and IWT SBO 'NanoCoMIT' (140061), the European Commission under the 'PANA' project, Call H2020-NMP-2015-two-stage (grant 686009), and by the University of Leuven for program financing PF IMIR (10/017). Himmelreich, U (corresponding author), Katholieke Univ Leuven, Fac Med, Dept Imaging & Pathol, Biomed MRI, Herestr 49, B-3000 Leuven, Belgium ; Katholieke Univ Leuven, Mol Small Anim Imaging Ctr MoSAIC, Herestr 49, B-3000 Leuven, Belgium. antoinedhollander@hotmail.com; greetje.vandevelde@kuleuven.be; Hilde.Jans@imec.be; brmvanspauwen@gmail.com; elien.vermeersch@kuleuven.be; jithin.jose@fujifilm.com; tom.struys@sprofit.com; Tim.Stakenborg@imec.be; liesbet.lagae@imec.be; uwe.himmelreich@kuleuven.be

Human dental pulp stem cells (hDPSCs) are considered plausible candidates for cell-based therapies and non-invasive imaging techniques are necessary to evaluate stem cell therapy. Magnetic labeling with superparamagnetic iron oxide (SPIO) particles, allows in vivo visualization using MRI. This study hypothesized that SPIO particles can be used for long-term in vivo monitoring of hDPSCs, without affecting their differentiation potential. SPIO labeling did not interfere with adipogenic or osteogenic differentiation as evidenced by respectively the co-localization of lipid droplets and SPIO-containing endosomes and the capacity of SPIO-labeled hDPSCs to produce extracellular matrix. In vitro MRI showed that both adipogenic and osteogenic induced SPIO-labeled hDPSCs were able to significantly decrease T2* signal intensity after three weeks of in vitro culture. Furthermore, subcutaneously injected labeled adipogenic induced hDPSCs were detected by in vivo MRI. These results show great promi

Dental pulp stem cells (DPSC), mesenchymal stem cells (MSC) from the tooth, share phenotypical and multilineage characteristics with bone marrow derived MSCs (BMMSCs). Since DPSCs are much easier to harvest in comparison to BMMSCs they are considered as a useful alternative MSC source in stem cell research. As MSCs retain some plasticity, the neural differentiation potential of DPSCs will be evaluated. DPSCs will be labelled with the commercially available ferumoxide Endorem® to allow visualization with MRI following engraftment. This study shows expression of NeuN in neurogenic differentiated DPSCs. Future studies should include quantitative and electrophysiological experiments. This study also shows that the optimal concentration for labelling DPSCs is 0,75µg/ml PLL with 15µg/ml Endorem®. The influence of Endorem® labelling on cellular processes of DPSCs needs to be determined before these cells can be considered as a clinical applicable intracellular contrast agent for MRI analysi

PURPOSE: The use of stably integrated reporter gene imaging provides a manner to monitor the in vivo fate of engrafted cells over time in a non-invasive manner. Here, we optimized multimodal imaging (small-animal PET, Cerenkov luminescence imaging (CLI) and bioluminescence imaging (BLI)) of mesenchymal stem cells (MSCs), by means of the human sodium iodide symporter (hNIS) and firefly luciferase (Fluc) as reporters. METHODS: First, two multicistronic lentiviral vectors (LV) were generated for multimodal imaging: BLI, 124I PET/SPECT and CLI. Expression of the imaging reporter genes was validated in vitro using 99mTcO4- radioligand uptake experiments and BLI. Uptake kinetics, specificity and tracer elution were determined as well as the effect of the transduction process on the cell's differentiation capacity. MSCs expressing the LV were injected intravenously or subcutaneously and imaged using small-animal PET, CLI and BLI. RESULTS: The expression of both imaging reporter genes was functional and specific. An elution of 99mTcO4- from the cells was observed, with 31% retention after 3 h. After labeling cells with 124I in vitro, a significantly higher CLI signal was noted in hNIS expressing murine MSCs. Furthermore, it was possible to visualize cells injected intravenously using BLI or subcutaneously in mice, using 124I small-animal PET, CLI and BLI. CONCLUSIONS: This study identifies hNIS as a suitable reporter gene for molecular imaging with PET and CLI, as confirmed with BLI through the expression of Fluc. It supports the potential for a wider application of hNIS reporter gene imaging and future clinical applications. ispartof: PLOS ONE vol:9 issue:4 ispartof: location:United States status: published

Human dental pulp stem cells (HDPSC’s) is a term used for the remaining mesenchymal stem cell population in adult teeth. It has already been described that these cells exhibit odontogenic capacities when these cells are explanted into immunocompromised mice. They create a dentin-pulp like complex and in this way their use in tissue engineering and tooth regeneration seems very promising. However, there is still a lack of specific markers to identify this cell type. In this study, we investigated the immunoreactivity of HDPSC’s for metallothionein (MT), a Cystein-rich, low molecular weight protein. MT has the capacity to bind both physiological (Zn, Cu, Se,...) and xenobiotic (Cd, Hg, Ag,...) heavy metals through the thiol group of its cysteine residues. Furthermore, the immunoreactivity fot MT was tested in human pulp tissue and human bone-marrow derived mesenchymal stem cells.

Alzheimer's disease is the most common neurodegenerative disease, and many patients also present with vascular dysfunction. In this study, we aimed to assess cerebral blood flow (CBF) and cerebrovascular response (CVR) as early, pre-symptomatic (3 months of age), imaging markers in a bigenic model of Alzheimer's disease (APP.V717IxTau.P301L, biAT) and in the monogenic parental strains. We further developed our previously published combination of pulsed arterial spin labeling perfusion MRI and hypo-ventilation paradigm, which allows weaning of the mice from the ventilator. Furthermore, the commonly used isoflurane anesthesia induces vasodilation and is thereby inherently a vascular challenge. We therefore assessed perfusion differences in the mouse models under free-breathing isoflurane conditions. We report (i) that we can determine CBF and hypoventilation-based CVR under ketamine/midazolam anesthesia and wean mice from the ventilator, making it a valuable tool for assessment of CBF and CVR in mice, (ii) that biAT mice exhibit lower cortical CBF than wild-type mice at age 3 months, (iii) that CVR was increased in both biAT and APP.V717I mice but not in Tau.P301L mice, identifying the APP genotype as a strong influencer of brain CVR and (iv) that perfusion differences at baseline are masked by the widely used isoflurane anesthesia. Agentschap voor Innovatie door Wetenschap en Technologie, Grant/Award Number: SBO 130065; Fonds Wetenschappelijk Onderzoek, Grant/Award Number: 1.5.220.13N 11N0714N; FP7 Health, Grant/Award Number: F2-2011-278850; Horizon 2020 Framework Programme, Grant/Award Number: H2020-NMP-12-2015-686009; KU Leuven, Grant/Award Number: Program Financing IMIR (10/017) We gratefully acknowledge the following funding sources: the European Commission supported the INMiND project FP7 Health, Health-F2-2011-278850) and the PANA project (Horizon 2020 Framework Programme, H2020-NMP-12-2015-686009). The Flemish government (Innovation through Science and Technology, Agentschap voor Innovatie door Wetenschap en Technologie) supported the IWT MIRIAD (SBO 130065) project. The Research Foundation Flanders (Fonds Wetenschappelijk Onderzoek) supported KG (FWO scholarship 11N0714N) and TD (FWO-KaN 1.5.220.13 N). The University of Leuven (KU Leuven) supported the Program Financing IMIR (10/017).