Combined Plasma and Tissue Proteomic Study of Atherogenic Model Mouse: Approach To Elucidate Molecular Determinants in Atherosclerosis Development.

Atherogenic cardiovascular diseases are the major cause of mortality. Prevention and prediction of incidents is important; however, biomarkers that directly reflect the disease progression remain poorly investigated. To elucidate molecular determinants of atherogenesis, proteomic approaches are advantageous by using model animals for comparing changes occurring systematically (bloodstream) and locally (lesion) in accordance with the disease progression stages. We conducted differential mass spectrometric analysis between apolipoprotein E deficient (apoED) and wild-type (wt) mice using the plasma and arterial tissue of both types of mice obtained at four pathognomonic time points of the disease. A total of 100 proteins in the plasma and 390 in the arterial tissues were continuously detected throughout the four time points; 29 were identified in common. Of those, 13 proteins in the plasma and 36 in the arterial tissues showed significant difference in abundance between the apoED and wt mice at certain time points. Importantly, we found that quantitative variation patterns regarding the pathognomonic time points did not always correspond between the plasma and arterial tissues, resulting in gaining insight into atherosclerotic plaque progression. These characteristic proteins were found to be components of inflammation, thrombus formation, and vascular remodeling, suggesting drastic and integrative alteration in accordance with atherosclerosis development.

Analysis of extracellular vesicles as a potential index for monitoring differentiation of neural lineage cells from induced pluripotent stem cells.

To improve cell production efficacy, it is important to evaluate cell conditions during culture. Extracellular vesicles (EVs) secreted from various cells are involved in stem cell differentiation. As EVs carry information about their source cells, we hypothesized that they may serve as a noninvasive index of cell conditions. We evaluated changes in EV morphology, concentration, and microRNA (miRNA) and protein expression in culture supernatants during the differentiation of induced pluripotent stem cells (iPSCs) into neural lineage cells, for application in regenerative medicine for Parkinson's disease. We observed EVs (50-150 nm) in culture supernatants of iPSCs and differentiated cells. The EVs expressed the exosome markers CD63, CD81, and CD9. Throughout differentiation, the EV concentration in the supernatants decreased, and EV miRNA and protein expression changed substantially. Especially, miR-106b, involved in neural stem cell differentiation and normal brain development, was considerably downregulated. CD63 expression correlated with the CORIN-positive cell rate, which is an index of differentiation. Thus, EV concentration and miRNA and protein expression may reflect the differentiation status of iPSCs. These findings pave the way for the development of novel and sensitive cell culture monitoring methods.

Nuclear transplantation between allogeneic cells through topological reconnection of plasma membrane in a microfluidic system.

Previous studies have demonstrated that somatic cells fused with pluripotent stem cells can be reprogrammed on the basis of reprogramming factors acquired from the latter. However, fusion-reprogrammed cells are deemed unsuitable for therapeutic applications mainly because conventional fusion techniques often yield tetraploid fusants that contain exogenous genes acquired from the fusion partners. Here, we present a novel cell-cell topological reconnection technique and demonstrate its application to nuclear transplantation between a somatic cell and a stem cell without nuclei mixing. As a proof of concept, a microfluidic fusion chip embodied with a microslit (4 µm in width) to prevent nuclei mixing was developed and used to perform one-to-one electrofusion of a target somatic cell (Jurkat cell) with an induced pluripotent stem (iPS) cell. To extract its cytoplasm, the target cell was first topologically connected to a sacrificial iPS cell by electrofusion via a microslit, followed by shear flow removal of the latter to obtain a cytoplasm-depleted nucleus of the target cell. Then, to replace the lost cytoplasm, topological reconnection to a second iPS cell was performed similarly by electrofusion, followed by shear flow separation of the target cell to enable it acquire most of the iPS cytoplasm, but without nuclei mixing. Microscopic observation of target cells harvested and cultured post hoc in a microwell confirmed that they manifested cell division. Taken together, these results demonstrate the potential application of the cell-cell topological reconnection technique to somatic cell nuclear transplantation for the generation of autologous pluripotent stem cells.

Fabricating retinal pigment epithelial cell sheets derived from human induced pluripotent stem cells in an automated closed culture system for regenerative medicine.

Regenerative medicine has received a lot of attention as a novel strategy for injuries and diseases that are difficult to cure using current techniques. Cell production, which is vital for regenerative medicine, has undergone remarkable progress via breakthroughs in developmental biology and tissue engineering; currently, cell production requires numerous experimental operators performing manual, small-scale cell cultures. Other major obstacles for cell production and regenerative medicine include the variable quality of products based on the experimental procedure, the skills of operators, the level of labor required for production, and costs. Technological developments are required to overcome this, including automation instead of manual culture. Age-related macular regeneration (AMD) is a refractory ocular disease that causes severe deterioration in central vision due to senescence in the retinal pigment epithelium (RPE). Recently, we performed an autologous transplantation of induced pluripotent stem (iPS) cell-derived RPE cell sheets and started clinical research on allografts from RPE cell suspensions differentiated from iPS cells. The use of regenerative therapies for AMD using iPS cell-derived RPE is expected to become more widespread. In the present study, human iPS cell-derived RPE cells were cultured to form RPE cell sheets using equipment with a closed culture module. The quality of the automated cultured RPE cell sheets was confirmed by comparing their morphological and biological properties with those of manually generated RPE cell sheets. As a result, machine-cultured RPE sheets displayed the same quality as manually cultured RPE sheets, showing that iPS cell-derived RPE cell sheets were successfully cultured by an automated process.

Fabrication of tissue-engineered cell sheets by automated cell culture equipment.

Most cells for regenerative medicine are currently cultured manually. In order to promote the widespread use of regenerative medicine, it will be necessary to develop automated culture techniques so that cells can be produced in greater quantities at lower cost and with more stable quality. In the field of regenerative medicine technology, cell sheet therapy is an effective tissue engineering technique whereby cells can be grafted by attaching them to a target site. We have developed automated cell culture equipment to promote the use of this cell sheet regenerative treatment. This equipment features a fully closed culture vessel and circuit system that avoids contamination with bacteria and the like from the external environment, and it was designed to allow 10 cell sheets to be simultaneously cultured in parallel. We used this equipment to fabricate 50 sheets of human oral mucosal epithelial cells in five automated culture tests in this trial. By analyzing these sheets, we confirmed that 49 of the 50 sheets satisfied the quality standards of clinical research. To compare the characteristics of automatically fabricated cell sheets with those of manually fabricated cell sheets, we performed histological analyses using immunostaining and transmission electron microscopy. The results confirmed that cell sheets fabricated with the automated cell culture are differentiated in the same way as cultures fabricated manually.

Immunoglobulin G (IgG)-Based Imaging Probe Accumulates in M1 Macrophage-Infiltrated Atherosclerotic Plaques Independent of IgG Target Molecule Expression.

PURPOSE: Vulnerable plaques are key factors for ischemic diseases. Thus, their precise detection is necessary for the diagnosis of such diseases. Immunoglobulin G (IgG)-based imaging probes have been developed for imaging biomolecules related to plaque formation for the diagnosis of atherosclerosis. However, IgG accumulates nonspecifically in atherosclerotic regions, and its accumulation mechanisms have not yet been clarified in detail. Therefore, we explored IgG accumulation mechanisms in atherosclerotic lesions and examined images of radiolabeled IgG for the diagnosis of atherosclerosis. PROCEDURES: Mouse IgG without specificity to biomolecules was labeled with technetium-99m via 6-hydrazinonicotinate to yield [99mTc]IgG. ApoE-/- or C57BL/6J mice were injected intravenously with [99mTc]IgG, and their aortas were excised 24 h after injection. After radioactivity measurement, serial aortic sections were autoradiographically and histopathologically examined. RAW264.7 macrophages were polarized into M1 or M2 and then treated with [99mTc]IgG. The radioactivities in the cells were measured after 1 h of incubation. [99mTc]IgG uptake in M1 macrophages was also evaluated after the pretreatment with an anti-Fcγ receptor (FcγR) antibody. The expression levels of FcγRs in the cells were measured by western blot analysis. RESULTS: [99mTc]IgG accumulation levels in the aortas were significantly higher in apoE-/- mice than in C57BL/6J mice (5.1 ± 1.4 vs 2.8 ± 0.5 %ID/g, p < 0.05). Autoradiographic images showed that the accumulation areas highly correlated with the macrophage-infiltrated areas. M1 macrophages showed significantly higher levels of [99mTc]IgG than M2 or M0 (nonpolarized) macrophages [2.2 ± 0.3 (M1) vs 0.5 ± 0.1 (M2), 0.4 ± 0.1 (M0) %dose/mg protein, p < 0.01] and higher expression levels of FcγRI and FcγRII. [99mTc]IgG accumulation in M1 macrophages was suppressed by pretreatment with the anti-FcγR antibody [2.2 ± 0.3 (nonpretreatment) vs 1.2 ± 0.2 (pretreatment) %ID/mg protein, p < 0.01]. CONCLUSIONS: IgG accumulated in pro-inflammatory M1 macrophages via FcγRs in atherosclerotic lesions. Thus, the target biomolecule-independent imaging of active inflammation should be taken into account in the diagnosis of atherosclerosis using IgG-based probes.

Biological characteristics of intratumoral [F-18]­fluoromisonidazole distribution in a rodent model of glioma.

Accurate imaging to identify hypoxic regions in tumors is key for radiotherapy planning. [F-18]­fluoro-misonidazole ([F-18]-FMISO) is widely used for tumor hypoxia imaging and has the potential to optimize radiotherapy planning. However, the biological characteristics of intratumoral [F-18]-FMISO distribution have not yet been fully investigated. In hypoxic cells, the hypoxia-inducible factor-1 (HIF-1) target proteins that induce cellular proliferation and glucose metabolism, glucose transporter-1 (Glut-1) and hexokinase-II (HK-II), are upregulated. In this study, we determined the intratumoral distribution of [F-18]-FMISO by autoradiography (ARG) and compared it with pimonidazole uptake, expression of Glut-1, tumor proliferative activity (Ki-67 index) and glucose metabolism ([C-14]2-fluoro-2-deoxy-D-glucose uptake; [C-14]-FDG) in a glioma rat model. Five C6 glioma­bearing rats were injected with [F-18]-FMISO and [C-14]-FDG. After 90 min, the rats were injected with pimonidazole and 60 min later, the rats were sacrificed and tumor tissues were sectioned into slices. The adjacent slices were used for ARG and immunohistochemical (IHC) analyses of pimonidazole, Glut-1 and Ki-67. [F-18]-FMISO ARG images were divided into regions of high [F-18]-FMISO uptake (FMISO+) and low [F-18]-FMISO uptake (FMISO-). Pimonidazole and Glut-1 expression levels, Ki-67 index and [C-14]-FDG distribution were evaluated in the regions of interest (ROIs) placed on FMISO+ and FMISO-. [F-18]-FMISO distribution was generally consistent with pimonidazole distribution. The percentage of positively stained areas (% positive) of Glut-1 in FMISO+ was significantly higher compared to FMISO- (24 ± 8% in FMISO+ and 9 ± 4% in FMISO-; P<0.05). There were no significant differences in Ki-67 index and [C-14]-FDG uptake between FMISO+ and FMISO- (for Ki-67, 10 ± 5% in FMISO+ and 12 ± 5% in FMISO-, P=ns; for [C-14]-FDG, 1.4 ± 0.3% ID/g/kg in FMISO+ and 1.3 ± 0.3% ID/g/kg in FMISO-, P = ns). Intratumoral [F-18]-FMISO distribution reflected tumor hypoxia and expression of the hypoxia­related gene product Glut-1; it did not, however, reflect tumor proliferation or glucose metabolism. Our findings help elucidate the biological characteristics of intratumoral [F-18]-FMISO distribution that are relevant to radiotherapy planning.

Gene and protein analysis of brain derived neurotrophic factor expression in relation to neurological recovery induced by an enriched environment in a rat stroke model.

Although an enriched environment enhances functional recovery after ischemic stroke, the mechanism underlying this effect remains unclear. We previously reported that brain derived neurotrophic factor (BDNF) gene expression decreased in rats housed in an enriched environment for 4 weeks compared to those housed in a standard cage for the same period. To further clarify the relationship between the decrease in BDNF and functional recovery, we investigated the effects of differential 2-week housing conditions on the mRNA of BDNF and protein levels of proBDNF and mature BDNF (matBDNF). After transient occlusion of the right middle cerebral artery of male Sprague-Dawley rats, we divided the rats into two groups: (1) an enriched group housed multiply in large cages equipped with toys, and (2) a standard group housed alone in small cages without toys. Behavioral tests before and after 2-week differential housing showed better neurological recovery in the enriched group than in the standard group. Synaptophysin immunostaining demonstrated that the density of synapses in the peri-infarct area was increased in the enriched group compared to the standard group, while infarct volumes were not significantly different. Real-time reverse transcription polymerase chain reaction, Western blotting and immunostaining all revealed no significant difference between the groups. The present results suggest that functional recovery cannot be ascribed to an increase in matBDNF or a decrease in proBDNF but rather to other underlying mechanisms.

Detection of potential ion suppression for peptide analysis in nanoflow liquid chromatography/mass spectrometry.

A detection technique for ion suppression in liquid chromatography/mass spectrometry (LC/MS) was developed by adding a probe to an LC mobile phase at a certain concentration. The probe is so hydrophilic that it is not adsorbed in a reversed-phase nanoflow LC column, and, furthermore, has an isoelectric point of about 3, which is lower than that for most peptides and is close to the pH of the mobile phase. The intensity of the protonated probe molecule decreases much more than that of other peptides when ion suppression occurs. Thus, the occurrence of the ion suppression is detected by a decrease in the mass chromatogram for the protonated probe molecule, and the decrease ratio is higher than that for other ions.

Differential interactions of phytochrome A (Pr vs. Pfr) with monoclonal antibodies probed by a surface plasmon resonance technique.

Phytochromes are red- and far-red light-reversible photoreceptors for photomorphogenesis in plants. Phytochrome A is a dimeric chromopeptide that mediates very low fluence and high irradiance responses. To analyze the surface properties of phytochrome A (phyA), the epitopes of 21 anti-phyA monoclonal antibodies were determined by variously engineered recombinant phyA proteins and the dissociation constants of seven anti-phyA monoclonal antibodies with phyA were measured using a surface plasmon resonance (SPR)-based resonant mirror biosensor (IAsys). Purified oat phyA was immobilized on the sensor surface using a carboxymethyl dextran cuvette in advance, and the interactions of each chosen monoclonal antibody against phyA in either red light absorbing form (Pr) or far-red light absorbing form (Pfr) at different concentrations were monitored. The binding profiles were analyzed using the FAST Fit program of IAsys. The resultant values of dissociation constants clearly demonstrated the differential affinities between the phyA epitopes and the monoclonal antibodies dependent upon Pr vs. Pfr conformations. Monoclonal antibody mAP20 preferentially recognized the epitope at amino acids 653-731 in the Pr form, whereas mAA02, mAP21 and mAR07/mAR08 displayed preferential affinities for the Pfr's surfaces at epitopes 494-601 (the hinge region between the N- and C-terminal domains), 601-653 (hinge in PASI domain), and 772-1128 (C-terminal domain), respectively. The N-terminal extension (1-74) was not recognized by mAP09 and mAP15, suggesting that the N-terminal extreme is not exposed in the native conformation of phyA. On the other hand, the C-terminal domain becomes apparently exposed on Pr-to-Pfr phototransformation, suggesting an inter-domain cross-talk. The use of surface plasmon resonance spectroscopy offers a new approach to study the surface properties of phytochromes associated with the photoreversible structural changes, as well as for the study of protein-protein interactions of phytochromes with their interacting proteins involved in light signaling events in plants.

Structural requirement of bilin chromophore for the photosensory specificity of phytochromes A and B.

Phytochromes are an important class of chromoproteins that regulate many cellular and developmental responses to light in plants. The model plant species Arabidopsis thaliana possesses five phytochromes, which mediate distinct and overlapping responses to light. Photobiological analyses have established that, under continuous irradiation, phytochrome A is primarily responsible for plant's sensitivity to far-red light, whereas the other phytochromes respond mainly to red light. The present study reports that the far-red light sensitivity of phytochrome A depends on the structure of the linear tetrapyrrole (bilin) prosthetic group. By reconstitution of holophytochrome in vivo through feeding various synthetic bilins to chromophore-deficient mutants of Arabidopsis, the requirement for a double bond on the bilin D-ring for rescuing phytochrome A function has been established. In contrast, we show that phytochrome B function can be rescued with various bilin analogs with saturated D-ring substituents.