Yoko Itakura

Application of Magnetic Nanoparticles to Gene Delivery

Nanoparticle technology is being incorporated into many areas of molecular science and biomedicine. Because nanoparticles are small enough to enter almost all areas of the body, including the circulatory system and cells, they have been and continue to be exploited for basic biomedical research as well as clinical diagnostic and therapeutic applications. For example, nanoparticles hold great promise for enabling gene therapy to reach its full potential by facilitating targeted delivery of DNA into tissues and cells. Substantial progress has been made in binding DNA to nanoparticles and controlling the behavior of these complexes. In this article, we review research on binding DNAs to nanoparticles as well as our latest study on non-viral gene delivery using polyethylenimine-coated magnetic nanoparticles.

Lectin microarray analysis of pluripotent and multipotent stem cells

Stem cells have a capability to self‐renew and differentiate into multiple types of cells; specific markers are available to identify particular stem cells for developmental biology research. In this study, we aimed to define the status of somatic stem cells and the pluripotency of human embryonic stem (hES) and induced pluripotent stem (iPS) cells using a novel molecular methodology, lectin microarray analysis. Our lectin microarray analysis successfully categorized murine somatic stem cells into the appropriate groups of differentiation potency. We then classified hES and iPS cells by the same approach. Undifferentiated hES cells were clearly distinguished from differentiated hES cells after embryoid formation. The pair‐wise comparison means based on ‘false discovery rate’ revealed that three lectins ‐Euonymus europaeus lectin (EEL), Maackia amurensis lectin (MAL) and Phaseolus vulgaris leucoagglutinin [PHA(L)]‐ generated maximal values to define undifferentiated and differentiated hES cells. Furthermore, to define a pluripotent stem cell state, we generated a discriminant for the undifferentiated state with pluripotency. The discriminant function based on lectin reactivities was highly accurate for judgment of stem cell pluripotency. These results suggest that glycomic analysis of stem cells leads to a novel comprehensive approach for quality control in cell‐based therapy and regenerative medicine.

Large-scale cell production of stem cells for clinical application using the automated cell processing machine

BackgroundCell-based regeneration therapies have great potential for application in new areas in clinical medicine, although some obstacles still remain to be overcome for a wide range of clinical applications. One major impediment is the difficulty in large-scale production of cells of interest with reproducibility. Current protocols of cell therapy require a time-consuming and laborious manual process. To solve this problem, we focused on the robotics of an automated and high-throughput cell culture system. Automated robotic cultivation of stem or progenitor cells in clinical trials has not been reported till date. The system AutoCulture® used in this study can automatically replace the culture medium, centrifuge cells, split cells, and take photographs for morphological assessment. We examined the feasibility of this system in a clinical setting.ResultsWe observed similar characteristics by both the culture methods in terms of the growth rate, gene expression profile, cell surface profile by fluorescence-activated cell sorting, surface glycan profile, and genomic DNA stability. These results indicate that AutoCulture® is a feasible method for the cultivation of human cells for regenerative medicine.ConclusionsAn automated cell-processing machine will play important roles in cell therapy and have widespread use from application in multicenter trials to provision of off-the-shelf cell products.

Engineering a versatile tandem repeat-type α2-6sialic acid-binding lectin

Previously, we developed an alpha2-6-sialic acid (Sia)-specific lectin (SRC) starting from an R-type galactose-specific lectin C-terminal domain. However, it showed relatively low affinity because of its monovalency. Here, we engineered a tandem repeat construct (SRC2) showing substantial affinity for alpha2,6-sialylated N-glycans (in the order of 10(-6)M in K(d)), almost comparable to a natural alpha2-6Sia-specific lectin from Sambucus sieboldiana (SSA). Notably, its binding to branched N-glycans was found to be more selective than SSA. Nevertheless, SRC2 showed no apparent hemagglutinating activity, while it exerted strong erythrocyte-binding activity. This unique feature will help flow cytometry analysis, where usual lectins including SSA agglutinate cells. Some other biochemical properties investigated for SRC2, e.g., high productivity in bacteria and easy release of captured glycoproteins with lactose have demonstrated versatility of this mutant protein as a powerful tool for sialoglycomics.

Novel detergent for whole organ tissue engineering.

Whole organ tissue engineering for various organs, including the heart, lung, liver, and kidney, has demonstrated promising results for end-stage organ failure. However, the sodium dodecyl sulfate (SDS)-based protocol for standard decellularization has drawbacks such as clot formation in vascularized transplantation and poor cell engraftment in recellularization procedures. Preservation of the surface milieu of extracellular matrices (ECMs) might be crucial for organ generation based on decellularization/recellularization engineering. We examined a novel detergent, sodium lauryl ether sulfate (SLES), to determine whether it could overcome the drawbacks associated with SDS using rat heart and kidney. Both organs were perfused in an antegrade fashion with either SLES or SDS. Although immunohistochemistry for collagen I, IV, laminin, and fibronectin showed similar preservation in both detergents, morphological analysis using scanning electron microscopy and an assay of glycosaminoglycan content on ECMs showed that SLES-treated tissues had better-preserved ECMs than SDS-treated tissues. Mesenteric transplantation revealed SLES did not induce significant inflammation, as opposed to SDS. Platelet adhesion to decellularized tissues was significantly reduced with SLES. Overall, SLES could replace older detergents such as SDS in the decellularization process for generation of transplantable recellularized organs.

N- and O-glycan cell surface protein modifications associated with cellular senescence and human aging

BackgroundGlycans play essential roles in biological functions such as differentiation and cancer. Recently, glycans have been considered as biomarkers for physiological aging. However, details regarding the specific glycans involved are limited. Here, we investigated cellular senescence- and human aging-dependent glycan changes in human diploid fibroblasts derived from differently aged skin donors using a lectin microarray.ResultsWe found that α2-6sialylated glycans in particular differed between elderly- and fetus-derived cells at early passage. However, both cell types exhibited sequentially decreasing α2-3sialylated O-glycan structures during the cellular senescence process and showed similar overall glycan profiles.ConclusionsWe observed a senescence-associated decrease in sialylation and increase in galactose exposure. Therefore, glycan profiling using lectin microarrays might be useful for the characterization of biomarkers of aging.

Sugar-Binding Profiles of Chitin-Binding Lectins from the Hevein Family: A Comprehensive Study

Chitin-binding lectins form the hevein family in plants, which are defined by the presence of single or multiple structurally conserved GlcNAc (N-acetylglucosamine)-binding domains. Although they have been used as probes for chito-oligosaccharides, their detailed specificities remain to be investigated. In this study, we analyzed six chitin-binding lectins, DSA, LEL, PWM, STL, UDA, and WGA, by quantitative frontal affinity chromatography. Some novel features were evident: WGA showed almost comparable affinity for pyridylaminated chitotriose and chitotetraose, while LEL and UDA showed much weaker affinity, and DSA, PWM, and STL had no substantial affinity for the former. WGA showed selective affinity for hybrid-type N-glycans harboring a bisecting GlcNAc residue. UDA showed extensive binding to high-mannose type N-glycans, with affinity increasing with the number of Man residues. DSA showed the highest affinity for highly branched N-glycans consisting of type II LacNAc (N-acetyllactosamine). Further, multivalent features of these lectins were investigated by using glycoconjugate and lectin microarrays. The lectins showed substantial binding to immobilized LacNAc as well as chito-oligosaccharides, although the extents to which they bound varied among them. WGA showed strong binding to heavily sialylated glycoproteins. The above observations will help interpret lectin-glycoprotein interactions in histochemical studies and glyco-biomarker investigations.

Ganglioside GM1 Contributes to the State of Insulin Resistance in Senescent Human Arterial Endothelial Cells.

Background: The roles of gangliosides in senescent endothelial cells (ECs) were unknown. Results: Ganglioside GM1 increased on senescent and aged ECs. GM1 contributes to the impairment of insulin signaling in ECs. Conclusion: Increased GM1 with senescence and aging contributes to insulin resistance in ECs. Significance: GM1 is the first known contributor to insulin resistance in ECs. Vascular endothelial cells (ECs) play central roles in physiologically important functions of blood vessels and contribute to the maintenance of vascular integrity. Therefore, it is considered that the impairment of EC functions leads to the development of vascular diseases. However, the molecular mechanisms of the EC dysfunctions that accompany senescence and aging have not yet been clarified. The carbohydrate antigens carried by glycoconjugates (e.g. glycoproteins, glycosphingolipids, and proteoglycans) mainly present on the cell surface serve not only as marker molecules but also as functional molecules. In this study, we have investigated the abundance and functional roles of glycosphingolipids in human ECs during senescence and aging. Among glycosphingolipids, ganglioside GM1 was highly expressed in abundance on the surface of replicatively and prematurely senescent ECs and also of ECs derived from an elderly subject. Insulin signaling, which regulates important functions of ECs, is impaired in senescent and aged ECs. Actually, by down-regulating GM1 on senescent ECs and overloading exogenous GM1 onto non-senescent ECs, we showed that an increased abundance of GM1 functionally contributes to the impairment of insulin signaling in ECs. Taken together, these findings provide the first evidence that GM1 increases in abundance on the cell surface of ECs under the conditions of cellular senescence and aging and causes insulin resistance in ECs. GM1 may be an attractive target for the detection, prevention, and therapy of insulin resistance and related vascular diseases, particularly in older people.

Podocalyxin-Targeting Comparative Glycan Profiling Reveals Difference between Human Embryonic Stem Cells and Embryonal Carcinoma Cells

Background: Human embryonic stem cells (hESCs) and human embryonal carcinoma cells (hECCs) have been extensively used for stem cell research. Although these cells are known to share many properties including high developmental capability and cell surface antigens, their origins are basically different: hECSs are derived from inner cell mass of blastocysts, while hECCs are from malignant tumors. Thus, the lack of a good method to differentiate these pluripotent cells remains a critical issue to diagnose tumorigenic potential of pluripotent stem cells for their medical applications. In this context, development of specific markers to distinguish hESCs from hECCs is also of clinical value. Method: In this study, we focused our glycan analysis on a carbohydrate-rich glycoprotein, podocalyxin, known as a carrier of TRA-1-60 and TRA-1-81 antigens, which represent hESC glycan markers. The target glycoprotein semi-quantified by immunoblotting was enriched from the cell extracts by immunoprecipitation, and the glycosylation differences occurring between hESCs and hECCs were systematically analyzed by an advanced technology of lectin microarray, antibody-overlay lectin profiling (ALP). Profiles of human embryonic bodies (hEBs) differentiated from hESCs were also analyzed. Results and Conclusion: A glycan profile of podocalyxin from hECCs was significantly different from that of hESCs. Lectin signals corresponding to α2-6 linked sialic acid were elevated in the hECCs, and glycosidase digestions further revealed significant difference in the non-reducing terminal and penultimate structures. These results demonstrate that the present procedure with focus on a particular glycoprotein could enhance relatively small but significant differences between closely related cells like hESCs and hECCs at the glycome level. The present finding will be helpful to develop a diagnostic method to distinguish undifferentiated stem cells from differentiated ones used for regenerative therapy.

Characteristic glycopeptides associated with extreme human longevity identified through plasma glycoproteomics

BACKGROUND Glycosylation is highly susceptible to changes of the physiological conditions, and accordingly, is a potential biomarker associated with several diseases and/or longevity. Semi-supercentenarians (SSCs; older than 105 years) are thought to be a model of human longevity. Thus, we performed glycoproteomics using plasma samples of SSCs, and identified proteins and conjugated N-glycans that are characteristic of extreme human longevity. METHODS Plasma proteins from Japanese semi-supercentenarians (SSCs, 106-109 years), aged controls (70-88 years), and young controls (20-38 years) were analysed by using lectin microarrays and liquid chromatography/mass spectrometry (LC/MS). Peak area ratios of glycopeptides to corresponding normalising peptides were subjected to orthogonal projections to latent structures discriminant analysis (OPLS-DA). Furthermore, plasma levels of clinical biomarkers were measured. RESULTS We found two lectins such as Phaseolus vulgaris, and Erythrina cristagalli (ECA), of which protein binding were characteristically increased in SSCs. Peak area ratios of ECA-enriched glycopeptides were successfully discriminated between SSCs and controls using OPLS-DA, and indicated that tri-antennary and sialylated N-glycans of haptoglobin at Asn207 and Asn211 sites were characterized in SSCs. Sialylated glycans of haptoglobin are a potential biomarker of several diseases, such as hepatocellular carcinoma, liver cirrhosis, and IgA-nephritis. However, the SSCs analysed here did not suffer from these diseases. CONCLUSIONS Tri-antennary and sialylated N-glycans on haptoglobin at the Asn207 and Asn211 sites were abundant in SSCs and characteristic of extreme human longevity. GENERAL SIGNIFICANCE We found abundant glycans in SSCs, which may be associated with human longevity.