36 research outputs found
A comparison of time-of-flight mr angiography, contrast-enhanced mr angiography and ct angiography to evaluate vessel area in a rabbit peripheral arterial disease model
1050 Applicability of perfusion MRI in monitoring cell-based therapy in a rabbit hindlimb ischemia model
Clinically Translatable Cell Tracking and Quantification by MRI in Cartilage Repair Using Superparamagnetic Iron Oxides
Background: Articular cartilage has very limited intrinsic regenerative capacity, making cell-based therapy a tempting approach for cartilage repair. Cell tracking can be a major step towards unraveling and improving the repair process of these therapies. We studied superparamagnetic iron oxides (SPIO) for labeling human bone marrow-derived mesenchymal stem cells (hBMSCs) regarding effectivity, cell viability, long term metabolic cell activity, chondrogenic differentiation and hBMSC secretion profile. We additionally examined the capacity of synovial cells to endocytose SPIO from dead, labeled cells, together with the use of magnetic resonance imaging (MRI) for intra-articular visualization and quantification of SPIO labeled cells. Methodology/Prinicipal Findings: Efficacy and various safety aspects of SPIO cell labeling were determined using appropriate assays. Synovial SPIO re-uptake was investigated in vitro by co-labeling cells with SPIO and green fluorescent protein (GFP). MRI experiments were performed on a clinical 3.0T MRI scanner. Two cell-based cartilage repair techniques were mimicked for evaluating MRI traceability of labeled cells: intra-articular cell injection and cell implantation in cartilage defects. Cells were applied ex vivo or in vitro in an intra-articular environment and immediately scanned. SPIO labeling was effective and did not impair any of the studied safety aspects, including hBMSC secretion profile. SPIO from dead, labeled cells could be taken up by synovial cells. Both injected and implanted SPIO-labeled cells could accurately be visualized by MRI in a clinically relevant sized joint model using clinically applied cell doses. Finally, we quantified the amount of labeled cells seeded in cartilage defects using MR-based relaxometry. Conclusions: SPIO labeling appears to be safe without influencing cell behavior. SPIO labeled cells can be visualized in an intra-articular environment and quantified when seeded in cartilage defects.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin
Labeling of cynomolgus monkey bone marrow-derived mesenchymal stem cells for cell tracking by multimodality imaging
Hydrogel-based scaffolds to support intrathecal stem cell transplantation as a gateway to the spinal cord: clinical needs, biomaterials, and imaging technologies
The prospects for cell replacement in spinal cord diseases are impeded by inefficient stem
cell delivery. The deep location of the spinal cord and complex surgical access, as well as
densely packed vital structures, question the feasibility of the widespread use of multiple
spinal cord punctures to inject stem cells. Disorders characterized by disseminated
pathology are particularly appealing for the distribution of cells globally throughout the
spinal cord in a minimally invasive fashion. The intrathecal space, with access to a
relatively large surface area along the spinal cord, is an attractive route for global stem cell
delivery, and, indeed, is highly promising, but the success of this approach relies on the
ability of cells 1) to survive in the cerebrospinal fluid (CSF), 2) to adhere to the spinal cord
surface, and 3) to migrate, ultimately, into the parenchyma. Intrathecal infusion of cell
suspension, however, has been insufficient and we postulate that embedding
transplanted cells within hydrogel scaffolds will facilitate reaching these goals. In this
review, we focus on practical considerations that render the intrathecal approach clinically
viable, and then discuss the characteristics of various biomaterials that are suitable to
serve as scaffolds. We also propose strategies to modulate the local microenvironment
with nanoparticle carriers to improve the functionality of cellular grafts. Finally, we
provide an overview of imaging modalities for in vivo monitoring and characterization of
biomaterials and stem cells. This comprehensive review should serve as a guide for those
planning pre-clinical and clinical studies on intrathecal stem cell transplantation.Funds provided under the project NanoTech4ALS (ref. ENMed/0008/2015, 13/EuroNanoMed/2016), funded under the EU FP7 M-ERA.NET program, Strategmed 1/233209/12/NCBIR/2015, and NIH R01 NS091100. The FCT distinction attributed to J.M.O. under the Investigator FCT program (IF/01285/2015) is also gratefully acknowledgedinfo:eu-repo/semantics/publishedVersio
An Introduction to Algebraic Models for Rational G–Spectra
The project of Greenlees et al. on understanding rational G-spectra in terms of algebraic categories has had many successes, classifying rational G-spectra for finite groups, SO(2), O(2), SO(3), free and cofree G-spectra as well as rational toral G-spectra for arbitrary compact Lie groups. This chapter provides an introduction to the subject in two parts. The first discusses rational G-Mackey functors, the action of the Burnside ring and change of group functors. It gives a complete proof of the well-known classification of rational Mackey functors for finite G. The second part discusses the methods and tools from equivariant stable homotopy theory needed to obtain algebraic models for rational G-spectra. It gives a summary of the key steps in the classification of rational G-spectra in terms of a symmetric monoidal algebraic category. Having these two parts in the same place allows one to see clearly the analogy between the algebraic and topological classifications
Surveillance écologique des sols par les bioindicateurs : relations doses-effets de 4 contaminants pris individuellement
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