Magnetic resonance imaging of mesenchymal stem cells labeled with dual (MR and fluorescence) agents in rat spinal cord injury.
ABSTRACT In vivo tracking cells using gadolinium-based contrast agents have the important advantage of providing a positive contrast on T1-weighted images, which is less likely to be confused with artifacts because of postoperative local signal voids such as metal, hemorrhage, or air. The aim of this study is to paramagnetically and fluorescently label marrow with dual agents (gadolinium-diethylene triamine penta-acetic acid [Gd-DTPA] and PEI-FluoR) and track them after transplantation into spinal cord injury (SCI) with magnetic resonance imaging (MRI).
Marrow mesenchymal stem cells (MSCs) from Sprague-Dawley rats were incubated with PEI-FluoR (rhodamine-conjugated PEI-FluoR) and Gd-DTPA complex for labeling. After labeling, cellular viability, proliferation, and apoptosis were evaluated. T1 value and longevity of intracellular Gd-DTPA retention were measured on a 1.5 T MRI scanner. Thirty-six SCI rats were implanted with labeled and unlabeled MSCs and phosphate-buffered saline. Then, serial MRI and Basso-Beattie-Bresnehan (BBB) locomotor tests were performed and correlated with fluorescent microscopy. The relative signal intensity (RSL) of the engraftment in relation to normal cord was measured and the linear mixed model followed by post-hoc Bonferroni test was used to identify significant differences in RSL as well as BBB score.
MSCs could be paramagnetically and fluorescently labeled by the dual agents. The labeling did not influence the cellular viability, proliferation, and apoptosis. The longevity of Gd-DTPA retention in labeled MSCs was up to 21 days. The distribution and migration of labeled MSCs in SCI lesions could be tracked until 7 days after implantation on MRI. The relative signal intensities of SCI rats treated with labeled cells at 1 day and 3 days (1.34 +/- 0.02, 1.27 +/- 0.03) were significantly higher than rats treated with unlabeled cells (0.94 +/- 0.01, 0.99 +/- 0.02) and phosphate-buffered saline (0.91 +/- 0.01, 0.95 +/- 0.01) (P < .05). Rats treated with labeled MSCs or unlabeled MSCs achieved significantly higher BBB scores than controls at 14, 21, 28, and 35 days after injury (P < .05).
Labeling MSCs with the dual agents may enable cellular MRI and tracking in experimental spinal cord injury.
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ABSTRACT: This study evaluates functional recovery after transplanting human bone marrow-derived stromal cells (BMSCs) into contusion models of spinal cord injury (SCI). The authors used a high-throughput process to expand BMSCs and characterized them by flow cytometry, ELISA, and gene expression. They found that BMSCs secrete neurotrophic factors and cytokines with therapeutic potential for cell survival and axon growth. In adult immune-suppressed rats, mild, moderate, or severe contusions were generated using the MASCIS impactor. One week following injury, 0.5 to 1 x 106 BMSCs were injected into the lesioned spinal cord; control animals received vehicle injection. Biweekly behavioral tests included the Basso, Beattie, and Bresnahan Locomotor Rating Scale (BBB), exploratory rearing, grid walking, and thermal sensitivity. Animals receiving moderate contusions followed by BMSC grafts showed significant behavioral recovery in BBB and rearing tests when compared to controls. Animals receiving BMSC grafts after mild or severe contusion showed trends toward improved recovery. Immunocytochemistry identified numerous axons passing through the injury in animals with BMSC grafts but few in controls. BMSCS were detected at 2 weeks after transplantation; however, at 11 weeks very few grafted cells remained. The authors conclude that BMSCs show potential for repairing SCI. However, the use of carefully characterized BMSCs improved transplantation protocols ensuring BMSC, survival, and systematic motor and sensory behavioral testing to identify robust recovery is imperative for further improvement.Neurorehabilitation and neural repair 07/2006; 20(2):278-96. · 4.28 Impact Factor
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ABSTRACT: Engraftment of olfactory ensheathing cells (OEC), a unique type of glia required for olfactory nerve growth throughout life, has been shown to foster axonal regeneration in different types of CNS and PNS injuries. However, a lack of suitable markers of OEC has hindered studies assessing survival and function of OEC grafts following transplantation. The aim of this study was to examine the possible usefulness of superparamagnetic iron oxide nanoparticles (magnetodendrimers) as a label to allow in vivo tracking of grafted OEC by MR imaging and to determine temporal and spatial migration of OEC in normal and injured rat spinal cords, including the possibility of such cells to cross a complete spinal cord injury zone. We found that labeled OEC were readily detectable in vivo by MR imaging for at least 2 months. Labeled OEC migrated extensively in normal spinal cord as shown by MRI and histological markers. In contrast, OEC showed limited migration in transected spinal cord and were not able to cross the transection gap. Furthermore, iron-containing hemorrhage products confounded interpretation of MR contrast patterns in the injured spinal cord. We conclude that (1) MR imaging is useful for noninvasive observation of cell migration dynamics after grafting in vivo, although interpretation in severe injuries should be cautious, and that (2) OEC migratory and thus regeneration-enhancing ability is limited when confronted with the glial scar of a transected spinal cord.Experimental Neurology 07/2004; 187(2):509-16. · 4.65 Impact Factor
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ABSTRACT: Stem and progenitor cells from various sources are currently recognized as entities with potential for the treatment of numerous neurodegenerative diseases. It has been observed in many animal models that transplantation of stem cells induces functional improvement. As a result of these findings, the first clinical cell transplantation trials were initiated, including those for Parkinson's disease and cerebral ischemia patients. However, in many patients, although modest improvements have been observed, these improvements were not sufficient to warrant invasive and possibly risky cell therapy. Thus, it is apparent that therapeutic success requires a better understanding of the mechanisms of action and the ability to control these mechanisms that underlie functional improvements, permitting amplification of the therapeutic effect. Considering the complexity of the nervous system, the task of repairing damaged or dysfunctional brain tissue with naïve cellular elements that require spatially and temporally accurate governance may seem daunting. However, the hope for faster and more inclusive progress in this field arises from recent developments in medical biotechnology that offers scientists increasingly sophisticated tools to study and control biological processes. One such technology with great potential for neurotransplantation is noninvasive cellular imaging. This tool allows real-time 'supervision' of grafted cells, as well as monitoring biodistribution and development. In this review, we highlight the current challenges in the field of cell-based therapy for neurodegenerative disorders and outline the role and capabilities of different cellular imaging techniques in addressing those issues.Neurodegenerative Diseases 02/2007; 4(4):306-13. · 3.41 Impact Factor