In vivo MRI stem cell tracking requires balancing of detection limit and cell viability

Copyright © 2010 Cognizant Comm. Corp

Ablation of cyclase-associated protein 2 (CAP2) leads to cardiomyopathy

Cyclase-associated proteins are highly conserved proteins that have a role in the regulation of actin dynamics. Higher eukaryotes have two isoforms, CAP1 and CAP2. To study the in vivo function of CAP2, we generated mice in which the CAP2 gene was inactivated by a gene-trap approach. Mutant mice showed a decrease in body weight and had a decreased survival rate. Further, they developed a severe cardiac defect marked by dilated cardiomyopathy (DCM) associated with drastic reduction in basal heart rate and prolongations in atrial and ventricular conduction times. Moreover, CAP2-deficient myofibrils exhibited reduced cooperativity of calcium-regulated force development. At the microscopic level, we observed disarrayed sarcomeres with development of fibrosis. We analyzed CAP2's role in actin assembly and found that it sequesters G-actin and efficiently fragments filaments. This activity resides completely in its WASP homology domain. Thus CAP2 is an essential component of the myocardial sarcomere and is essential for physiological functioning of the cardiac system, and a deficiency leads to DCM and various cardiac defects

Functional recovery after experimental spinal cord compression and whole body vibration therapy requires a balanced revascularization of the injured site

Purpose: Based on several positive effects of whole-body-vibration (WBV) therapy on recovery after SCI, we looked for correlations between functional (analysis of locomotion), electrophysiological (H-reflex) and morphological (density of functioning capillaries) measurements after SCI and WBV-treatment. Methods: Severe compression SCI at low-thoracic level (T8) in adult female Wistar rats was followed by WBV twice a day (2xWBV) over a 12-week post-injury period. Intact rats and rats with SCI but no WBV-therapy (No-WBV) served as controls. Recovery of locomotion was determined by BBB-locomotor rating, foot stepping angle (FSA), rump-height index (RHI), correct ladder steps (CLS) and H-reflex at 1, 3, 6, 9, and 12 weeks after SCI. Animals were sacrificed by an overdose of Isoflurane (Abbott). One hour later their spinal cords were fixed in 4% PFA for 24 h. Samples from the thoracic cord containing the lesion site and from the lumbar intumescence were cut into 10 mu m thick longitudinal frozen sections. Results: All functioning capillaries were unequivocally identified because the endogenous peroxidase of the erythrocytes was clearly visualized with 0.05% diaminobenzidine (DAB). A determination of their absolute (in mu m(2)) and proportional areas (percent of photographed tissue) revealed a significantly denser capillary network in the WBV-treated rats: 1,66 +/- 0,41% in the vibrated rats versus 0,79 +/- 0,19% in the No-WBV animals. The portion of the capillary network in intact rats was 1,51 +/- 0,69%. Surprisingly, even though the vascularization in the treated animals was significantly increased, this had no beneficial influence on the recovery of functions after SCI. Conclusion: The results of this study provide for the first time evidence that intensive WBV-therapy leads to a significantly denser capillary network in the lesioned spinal cord. However, since this higher capillary density is not associated with improved functional recovery (possibly because it exceeded the balance necessary for functional improvements), optional treatments with lower intensity or less time of WBV-therapy should be tested

Novel positively charged nanoparticle labeling for in vivo imaging of adipose tissue-derived stem cells.

Stem cell transplantation has been expected to have various applications for regenerative medicine. However, in order to detect and trace the transplanted stem cells in the body, non-invasive and widely clinically available cell imaging technologies are required. In this paper, we focused on magnetic resonance (MR) imaging technology, and investigated whether the trimethylamino dextran-coated magnetic iron oxide nanoparticle -03 (TMADM-03), which was newly developed by our group, could be used for labeling adipose tissue-derived stem cells (ASCs) as a contrast agent. No cytotoxicity was observed in ASCs transduced with less than 100 µg-Fe/mL of TMADM-03 after a one hour transduction time. The transduction efficiency of TMADM-03 into ASCs was about four-fold more efficient than that of the alkali-treated dextran-coated magnetic iron oxide nanoparticle (ATDM), which is a major component of commercially available contrast agents such as ferucarbotran (Resovist), and the level of labeling was maintained for at least two weeks. In addition, the differentiation ability of ASCs labeled with TMADM-03 and their ability to produce cytokines such as hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and prostaglandin E2 (PGE2), were confirmed to be maintained. The ASCs labeled with TMADM-03 were transplanted into the left kidney capsule of a mouse. The labeled ASCs could be imaged with good contrast using a 1T MR imaging system. These data suggest that TMADM-03 can therefore be utilized as a contrast agent for the MR imaging of stem cells

High-Resolution Cellular MRI: Gadolinium and Iron Oxide Nanoparticles for in-Depth Dual-Cell Imaging of Engineered Tissue Constructs

International audienceRecent advances in cell therapy and tissue engineering opened new windows for regenerative medicine, but still necessitate innovative noninvasive imaging technologies. We demonstrate that high-resolution magnetic resonance imaging (MRI) allows combining cellular-scale resolution with the ability to detect two cell types simultaneously at any tissue depth. Two contrast agents, based on iron oxide and gadolinium oxide rigid nanoplatforms, were used to "tattoo" endothelial cells and stem cells, respectively, with no impact on cell functions, including their capacity for differentiation. The labeled cells' contrast properties were optimized for simultaneous MRI detection: endothelial cells and stem cells seeded together in a polysaccharide-based scaffold material for tissue engineering appeared respectively in black and white and could be tracked, at the cellular level, both in vitro and in vivo. In addition, endothelial cells labeled with iron oxide nanoparticles could be remotely manipulated by applying a magnetic field, allowing the creation of vessel substitutes with in-depth detection of individual cellular components