[Survey on the Number and Percentage of MR Safety Labeling Changed for Implantable Medical Devices].

PURPOSE: The purposes of this study were to investigate the number and percentage of items that changed magnetic resonance (MR) safety information labeling for implantable medical devices (IMDs) and to confirm the importance of checking the latest MR safety information database (117 types and 10031 items). METHODS: We investigated the number and percentage of MR safety labeling changed for IMDs in the MR safety information database as of December 2021 and August 2022. RESULTS: IMDs of MR Safety Unlabeled decreased from 4116 items (41.1%) to 859 items (8.6%). IMDs of MR Conditional increased from 4141 items (41.3%) to 5896 items (58.8%). CONCLUSIONS: Since there have been changes in the MR safety labeling for many IMDs, this study shows that it is important to confirm the latest MR safety information for IMDs.

Impact of REDV peptide density and its linker structure on the capture, movement, and adhesion of flowing endothelial progenitor cells in microfluidic devices.

Ligand-immobilization to stents and vascular grafts is expected to promote endothelialization by capturing flowing endothelial progenitor cells (EPCs). However, the optimized ligand density and linker structure have not been fully elucidated. Here, we report that flowing EPCs were selectively captured by the REDV peptide conjugated with a short linker. The microchannel surface was modified with the REDV peptide via Gly-Gly-Gly (G3), (Gly-Gly-Gly)3 (G9), and diethylene glycol (diEG) linkers, and the moving velocity and captured ratio were evaluated. On the unmodified microchannels, the moving velocity of the cells exhibited a unimodal distribution similar to the liquid flow. The velocity of the endothelial cells and EPCs on the peptide-immobilized surface indicated a bimodal distribution, and approximately 20 to 30% of cells moved slower than the liquid flow, suggesting that the cells were captured and rolled on the surface. When the immobilized ligand density was lower than 1 molecule/nm2, selective cell capture was observed only in REDV with G3 and diEG linkers, but not in G9 linkers. An in silico study revealed that the G9 linker tends to form a bent structure, and the REDV peptide is oriented to the substrate side. These results indicated that REDV captured the flowing EPC in a sequence-specific manner, and that the short linker was more adequate.

Evaluation of Molecular Ordering in Bicelle Bilayer Membranes Based on Induced Circular Dichroism Spectra.

Bicelles are submicrometer-sized disc-shaped molecular self-assemblies that can be obtained in aqueous solution by dispersing mixtures of certain amphiphiles. Although phospholipid bicelle and phospholipid vesicle assemblies adopt similar lipid bilayer structures, the differences in bilayer characteristics, especially physicochemical properties such as bilayer fluidity, are not clearly understood. Herein, we report the lipid ordering properties of bicelle bilayer membranes based on induced circular dichroism (ICD) and fluorescence polarization analyses using 1,6-diphenyl-1,3,5-hexatriene (DPH) as a probe. Bicelles were prepared by using 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC), while pure DMPC vesicles and pure DHPC micelles were used as references. At temperatures below the phase transition temperature of DMPC, the bicelles showed lower membrane fluidities, whereas DHPC micelles showed higher membrane fluidity, suggesting no significant differences in bilayer fluidity between the bicelle and vesicle assemblies. The ICD signals of DPH were induced only when the membrane was in ordered (solid-ordered or ripple-gel) phases. In the bicelle systems, the ICD of DPH was more significant than that of the DMPC vesicle. The induced chirality of DPH was dependent on the chirality of the bilayer lipid. Compared to that of the DMPC/DHPC bicelle, the ICD of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/DHPC bicelle was higher, while that of the bovine sphingomyelin/DHPC bicelle was lower. Because the lipids are tightly packed in the ordered phase, the ICD intensity reflects the molecular ordering state of the lipids in the bicelle bilayer.

Label-Free Separation of Induced Pluripotent Stem Cells with Anti-SSEA-1 Antibody Immobilized Microfluidic Channel.

When induced pluripotent stem cells (iPSCs) are routinely cultured, the obtained cells are a heterogeneous mixture, including feeder cells and partially differentiated cells. Therefore, a purification process is required to use them in a clinical stage. We described a label-free separation of iPSCs using a microfluidic channel. Antibodies against stage-specific embryonic antigen 1 (SSEA-1) was covalently immobilized on the channel coated with a phospholipid polymer. After injection of the heterogeneous cell suspension containing iPSCs, the velocity of cell movement under a liquid flow condition was measured. The mean velocity of the cell movement was 2.1 mm/sec in the unmodified channel, while that in the channel with the immobilized-antibody was 0.4 mm/sec. The eluted cells were fractionated by eluting time. As a result, the SSEA-1 positive iPSCs were mainly contained in later fractions, and the proportion of iPSCs was increased from 43% to 82% as a comparison with the initial cell suspension. These results indicated that iPSCs were selectively separated by the microfluidic channel. This channel is a promising device for label-free separation of iPSCs based on their pluripotent state.