Teru Okitsu

The University of Tokyo, Edo, Tōkyō, Japan

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Publications (110)480.66 Total impact

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    ABSTRACT: A CMOS image sensor-based implantable glucose sensor based on an optical-sensing scheme is proposed and experimentally verified. A glucose-responsive fluorescent hydrogel is used as the mediator in the measurement scheme. The wired implantable glucose sensor was realized by integrating a CMOS image sensor, hydrogel, UV light emitting diodes, and an optical filter on a flexible polyimide substrate. Feasibility of the glucose sensor was verified by both in vitro and in vivo experiments.
    Biomedical Optics Express 11/2014; 5(11). · 3.18 Impact Factor
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    ABSTRACT: After producing α1-3galactosyltransferase knockout (GT-KO) pigs, most of the organs of these pigs showed less antigenicity to the human body. However, wild-type adult pig islets (API) that originally contained negligible levels of α-Gal, now showed a clear antigenicity to human serum. In this study, N-glycans were isolated from both APIs & human islets. Their structures were then analyzed by a mapping technique based on their HPLC elution positions and MALDI-TOF-MS data.Both preparations contained substantial amounts of high-mannose structures. The N-glycans from human islets were separated into 17 neutral, 8 mono-sialyl and 4 di-sialyl glycans, the API glycans were comprised of 11 neutral, 8 mono-sialyl, 3 di-sialyl, 2 mono-sulfated, 3 mono-sialyl-mono-sulfated and one di-sulfated glycan. Among them, the API preparation contained one neutral, five mono-sialyl glycans and six sulfated glycans that were not detected in human islets. The structures of nine of these twelve could be clearly determined. In addition, a study of the sulfate-depleted API suggests that sulfate residues could be antigenic to humans. The data herein will be helpful for future studies of the antigenicity associated with API.
    Glycobiology 02/2014; 24(2):125-38. · 3.54 Impact Factor
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    ABSTRACT: In living tissues, a cell is exposed to chemical substances delivered partially to its surface. Such a heterogeneous chemical environment potentially induces cell polarity. To evaluate this effect, we developed a microfluidic device that realizes spatially confined delivery of chemical substances at subcellular resolution. Our microfluidic device allows simple setup and stable operation for over 4 h to deliver chemicals partially to a single cell. Using the device, we showed that subcellular glucose exposure triggers an intracellular [Ca(2+)] change in the β-cells. In addition, the imaging of a cell expressing GFP-tagged insulin showed that continuous subcellular exposure to glucose biased the spatial distribution of insulin granules toward the site where the glucose was delivered. Our approach illustrates an experimental technique that will be applicable to many biological experiments for imaging the response to subcellular chemical exposure and will also provide new insights about the development of polarity of β-cells.
    Scientific Reports 01/2014; 4:4123. · 5.08 Impact Factor
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    ABSTRACT: PURPOSE: We performed lectin microarray analyses of islets from wild-type (WT) pigs and α1-3galactosyltransferase gene knockout (GKO) pigs and compared the results with the corresponding values for islets from healthy humans. METHODS: Islets were isolated from the pancreas. After sonication and centrifugation, the proteins in the supernatant from each islet were labeled with Cy3 and applied to a lectin array. RESULTS: Despite negligible expression of the Gal antigen on the adult pig islets (APIs), GKO-islets showed weaker signals, not only for GS-I-B4 but also for PNA, WFA, PTL-I, and GS-I-A4, than the WT islets, indicating reduced contents of α-linked GalNAc and Galβ1-3GalNAc. In comparing the islets of pigs vs. humans, human islets showed stronger signals for UEA-I, AAL, TJA-II, EEL, WFA, HPA, DBA, SBA and PTL-I, indicating that besides ABO blood type antigens, high levels of fucose and α-linked GalNAc are present. On the other hand, the high mannose form was very rich in the APIs. CONCLUSION: GKO reduced alpha-linked GalNAc, despite negligible expression of the Gal antigen on WT-API. On the other hand, the high-mannose form was richer in both APIs than in healthy human islets. These results provide useful information for future studies.
    Surgery Today 12/2013; 43(12):1439-47. · 0.96 Impact Factor
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    ABSTRACT: Besides α-Gal expression, the differences of glycosylation and antigenicity between adult pig islets (APIs) and neonatal porcine islet-like cell clusters (NPCCs) are altogether unclear. In this study, lectin microarray analyses of NPCCs were performed and the results compared with the corresponding values for wild-type APIs and NPCCs from α-Gal transferase knockout (GalT-KO) pig. NPCCs were isolated from 1-3-d-old neonatal wild-type pigs and cultured for 1 d, 5 d, and 9 d, using a previously described technique. Alternatively, the isoration of APIs were isolated based on the method for human islets. In a comparison between NPCCs and APIs, all of the NPCCs showed higher signals for Sambucus nigra, Sambucus sieboldiana, and Trichosanthes japonica I and the binding of α2,6 sialc acid, whereas the APIs showed stronger signals for Lotus tetragonolobus, Aleuria aurantia, Narcissus pseudonarcissus, and Galanthus nivalis, suggesting that APIs contain high levels of high-mannose forms. Among the NPCCs, NPCC (day1) appeared to be richer than the others in Lotus tetragonolobus, Narcissus pseudonarcissus, Galanthus nivalis, and Urtica dioica, implying the presence of high-mannose forms. However, as a whole, the signals for many lectins for NPCCs were very similar. The NPCCs from a GalT-KO pig indicated not only the downregulation of α-Gal expression but α-GalNAc as well, and α2-6 sialic acid was upregulated. The results reported herein contain useful information for the future production of immunomodified pigs with less antigenicity than GalT-KO pigs toward clinical applications of NPCCs.
    Journal of Surgical Research 07/2013; 183(1):412-8. · 2.02 Impact Factor
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    ABSTRACT: Artificial reconstruction of fibre-shaped cellular constructs could greatly contribute to tissue assembly in vitro. Here we show that, by using a microfluidic device with double-coaxial laminar flow, metre-long core-shell hydrogel microfibres encapsulating ECM proteins and differentiated cells or somatic stem cells can be fabricated, and that the microfibres reconstitute intrinsic morphologies and functions of living tissues. We also show that these functional fibres can be assembled, by weaving and reeling, into macroscopic cellular structures with various spatial patterns. Moreover, fibres encapsulating primary pancreatic islet cells and transplanted through a microcatheter into the subrenal capsular space of diabetic mice normalized blood glucose concentrations for about two weeks. These microfibres may find use as templates for the reconstruction of fibre-shaped functional tissues that mimic muscle fibres, blood vessels or nerve networks in vivo.
    Nature Material 03/2013; · 35.75 Impact Factor
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    ABSTRACT: In bottom-up tissue engineering, a method to integrate a pathway of nutrition and oxygen into the resulting macroscopic tissue has been highly desired, but yet to be established. This paper presents a cellular building unit made from microstrand-shaped bacterial cellulose (BC microstrand) covered with mammalian cells. The BC microstrands are fabricated by encapsulating Acetobacter xylinum with a calcium alginate hydrogel microtube using a double co-axial microfluidic device. The mechanical strength and porous property of the BC microstrands can be regulated by changing the initial density of the bacteria. By folding or reeling the building unit, we demonstrated the multiple shapes of millimeter-scale cellular constructs such as coiled and ball-of-yarn-shaped structures. Histological analysis of the cellular constructs indicated that the BC microstrand served as a pathway of nutrition and oxygen to feed the cells in the central region. These findings suggest that our approach facilitates creating functional macroscopic tissue used in various fields such as drug screening, wound healing, and plastic surgery.
    Biomaterials 01/2013; · 8.31 Impact Factor
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    ABSTRACT: We present a portable glucose monitoring system comprised of an implantable fluorescent-hydrogel sensor, wearable photo detector, microcontroller, wireless device and software for transdermal, continuous glucose monitoring. Although we showed the potential of the fluorescent-hydrogel fibers for applying to long-term, implanted glucose monitoring, “true” continuous glucose monitoring with a portable monitoring system has yet to be realized. In the system that we propose here, the calculated glucose values show a good correlation with the actual blood glucose concentrations. The portable device attached to the ear of a rat and measured the fluorescence intensity for three days. Therefore, our system shows the potential for practical, “true,” continuous glucose monitoring.
    Micro Electro Mechanical Systems (MEMS), 2013 IEEE 26th International Conference on; 01/2013
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    ABSTRACT: Preserving isolated islets at low temperature appears attractive because it can keep islet quantity comparable to freshly isolated islets. In this study, we evaluated the effect of serum as an additive to preservation solutions on islet quality after short-term hypothermic storage. Isolated mouse islets were preserved at 4°C in University of Wisconsin solution (UW) alone, UW with serum, M-Kyoto solution (MK) alone or MK with serum. We then assessed islet quantity, morphology, viability and function in vitro as well as in vivo. Islet quantity after storage in all four solutions was well maintained for up to 120 h. However, islets functioned for different duration; glucose-stimulated insulin release assay revealed that the duration was 72 h when islets were stored in UW with serum and MK with serum, but only 24 h in UW alone, and the islet function disappeared immediately in MK alone. Viability assay confirmed that more than 70% islet cells survived for up to 48 h when islets are preserved in UW with serum and MK with serum, but the viability decreased rapidly in UW alone and MK alone. In in vivo bioassays using 48-h preserved isogeneic islets, all recipient mice restored normal blood glucose concentrations by transplants preserved in UW with serum or MK with serum, whereas 33.3% recipients and no recipient restored diabetes by transplants preserved in UW alone and in MK alone respectively. Adding serum to both UW and MK improves their capability to store isolated islets by maintaining islet functional viability.
    Islets 01/2013; 5(1). · 1.55 Impact Factor
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    ABSTRACT: The pig pancreas is considered to be the most suitable source of islets for clinical xenotransplantation. Two types of islet transplantation are: adult pig islets and neonatal porcine islet-like cell clusters (NPCC). However, besides a-Gal expression, differences in glycosylation and xenoantigenicity between both types were not clear so fat to date. In this study, we performed lectin microarray analyses of NPCCs cultured for 1, 5, or 9 days. We studied differences in gycoantigens among several kinds of wild-type NPCCs isolated from 1- to 3-day-old neonatal wild-type pigs (Large White/Landrace × Duroc) and cultured for 1, 5 and 9 days in Ham's 10 in the presence of nicotinamide, using a previously published technique. After sonication and centrifugation, supernatant proteins from each islet were labeled with Cy3, applied to a lectin array and scanned with an SC-Profiler for evaluation using an Array Pro Analyzer. The overall signals of NPCC at days 5 and 9, showed almost the same values to most lectins, whereas those on day 1 showed differences, suggesting that the NPCC on day 1 contain immature cells that gradually turn to mature NPCCs in culture.
    Transplantation Proceedings 05/2012; 44(4):1134-5. · 0.95 Impact Factor
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    ABSTRACT: Polyacrylamide (PAM) hydrogels are widely used in bioanalysis and biosensing applications. Scaling down of PAM patterns to micro/nanosize extends PAM applications to lab-on-a-chip, highly sensitive biosensors and cell/tissue analysis. Proposed is a replica moulding technique to pattern the PAM surface down to nanosize. Various patterns on silicon moulds successfully transferred to PAM with a minimum dimension of 60 nm and aspect ratio of up to ~9. PAM is characterised as a platform for a single cell array and the analysis of cell responses to topographic cues. Moreover, micro/nanopatterned PAM samples were implanted under the back skin of rats to study the topological effects on immuno responses in vivo. Therefore the use of micro/nanoreplica moulding to pattern PAM hydrogel provides opportunities for studying the relationship between soft nanoscaled structures and cell/tissue.
    Micro & Nano Letters 01/2012; 7(11):1108-1111. · 0.85 Impact Factor
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    ABSTRACT: For islet transplantation, maintaining organ viability after pancreas procurement is critically important for optimal graft function and survival. We recently reported that islet yield was significantly higher in the modified ET-Kyoto (MK) solution, which includes a trypsin inhibitor (ulinastatin), compared with the UW solution, and that the advantages of MK solution are trypsin inhibition and less collagenase inhibition. In this study, we compared ulinastatin with other trypsin inhibitors, gabexate mesilate, and nafamostat mesilate, in preservation solution for islet isolation. Ulinastatin was easily dissolved in ET-Kyoto solution, while ET-Kyoto with gabexate mesilate and nafamostat mesilate became cloudy immediately after addition. Although there were no significant differences in islet yield among the three groups, viability was significantly higher for the MK group than for the GK group or the NK group. The stimulation index was significantly higher for the MK group than for the GK group. In summary, there are no other trypsin inhibitors that are more effective than ulinastatin. Based on these data, we now use ET-Kyoto solution with ulinastatin for clinical islet transplantation.
    Cell Transplantation 01/2012; 21(2-3):509-16. · 4.42 Impact Factor
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    ABSTRACT: We present a nano-patterned poly-acrylamide (PAAm) hydrogel that can reduce inflammatory effects after subcutaneous implantation. Although hydrogel is considered as an excellent biomaterial for implants due to its biocompatibility, hydrogel still induces inflammation after implantation. To enhance biocompatibility for subcutaneous implantable sensors, we modified hydrogel surface with nano-patterns using simple molding process. To test the anti-inflammatory effect, we implanted the samples to rat's back. Since macrophages play an important role in the immune response and development of encapsulation after inflammation reaction, we counted macrophages neighboring the implanted nano-patterned hydrogels after 3 and 7 days and measured thickness of encapsulation after 21 days from implantation. We found that the sample with the line-and-space pattern of 600 nm in space successfully suppressed the inflammation reaction. Therefore, nano-patterned hydrogel is promising for long-term subcutaneous implantable sensors.
    Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) 01/2012;
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    ABSTRACT: The use of fluorescence-based sensors holds great promise for continuous glucose monitoring (CGM) in vivo, allowing wireless transdermal transmission and long-lasting functionality in vivo. The ability to monitor glucose concentrations in vivo over the long term enables the sensors to be implanted and replaced less often, thereby bringing CGM closer to practical implementation. However, the full potential of long-term in vivo glucose monitoring has yet to be realized because current fluorescence-based sensors cannot remain at an implantation site and respond to blood glucose concentrations over an extended period. Here, we present a long-term in vivo glucose monitoring method using glucose-responsive fluorescent hydrogel fibers. We fabricated glucose-responsive fluorescent hydrogels in a fibrous structure because this structure enables the sensors to remain at the implantation site for a long period. Moreover, these fibers allow easy control of the amount of fluorescent sensors implanted, simply by cutting the fibers to the desired length, and facilitate sensor removal from the implantation site after use. We found that the polyethylene glycol (PEG)-bonded polyacrylamide (PAM) hydrogel fibers reduced inflammation compared with PAM hydrogel fibers, transdermally glowed, and continuously responded to blood glucose concentration changes for up to 140 days, showing their potential application for long-term in vivo continuous glucose monitoring.
    Proceedings of the National Academy of Sciences 08/2011; 108(33):13399-403. · 9.81 Impact Factor
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    ABSTRACT: In clinical islet transplantation, because the long-term insulin-independence rate is still poor, a method for detailed analysis of the transplanted islets in the liver after transplantation is required. We have established a novel imaging technique suitable for analysis of transplanted islets in liver using an optical projection tomography (OPT) method. A three-dimensional tomographic image of the transplanted islets in liver was reconstructed. The number of islets transplanted and the number of transplanted islets observed using OPT showed good correlation. The OPT method was used to compare the numbers of transplanted islets in mouse syngeneic and allogeneic transplantation models. Blood glucose concentrations of streptozotocin (STZ)-induced diabetic mice transplanted with syngeneic islets remained normoglycemic and the number of transplanted islets was largely preserved 11 days after transplantation. In mice transplanted with allogeneic islets, hyperglycemia recurred from 7 days after transplantation and the number and the volume of transplanted islets was significantly reduced 11 days after transplantation. These results indicate that OPT imaging and analysis may be a useful tool to quantitatively and sterically evaluation of transplanted islets in liver at the cellular level.
    Transplant International 05/2011; 24(8):839-44. · 3.16 Impact Factor
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    ABSTRACT: Islet damage attributed to impaired exocrine cells during pancreas preservation and isolation procedure remains elusive, although released exocrine enzymes could directly damage islets. The aim of this study is to investigate the cellular mechanisms associated with exocrine cells and their possible impact on the islet cell survival and function after isolation. Mouse pancreata were stored in cold University of Wisconsin preservation solution for 0, 24 and 48 h and incubated with or without collagenase at 37°C for 15 min. During preservation, the percentage of exocrine cells with necrosis, which means impaired cellular membrane that allows intracellular enzymes to be released, remains low (< 10%) regardless of preservation time; whereas the percentage of exocrine cells with apoptosis, which means impaired nucleus and possible intact cellular membrane, increases over time of preservation. After collagenase-free incubation, however, the percentage of exocrine cells with necrosis became higher in longer preservation time, and more than 60% of the necrotic exocrine cells contained apoptosis as well. Islet cells located in pancreata with intact structure are almost kept away either from necrotic or apoptotic changes even after 48 h preservation followed by collagenase-free incubation. However, when islets are isolated after collagenase-containing incubation, the percentage of islet cells with necrosis increases over time of preservation up to approximately 40%. This study suggests that exocrine cells with necrosis could cause damage of isolated islets when the pancreas is dissociated and that the necrosis in exocrine cells might be induced mainly as the conversion from apoptosis that has already existed during preservation.
    Islets 05/2011; 3(3):102-10. · 1.55 Impact Factor
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    ABSTRACT: Fluorescent microbeads hold great promise for in vivo continuous glucose monitoring with wireless transdermal transmission and long-lasting activity. The full potential of fluorescent microbeads has yet to be realized due to insufficient intensity for transdermal transmission and material toxicity. This paper illustrates the highly-sensitive, biostable, long-lasting, and injectable fluorescent microbeads for in vivo continuous glucose monitoring. We synthesized a fluorescent monomer composed of glucose-recognition sites, a fluorogenic site, spacers, and polymerization sites. The spacers are designed to be long and hydrophilic for increasing opportunities to bind glucose molecules; consequently, the fluorescent monomers enable high-intensive responsiveness to glucose. We then fabricated injectable-sized fluorescent polyacrylamide hydrogel beads with high uniformity and high throughput. We found that our fluorescent beads provide sufficient intensity to transdermally monitor glucose concentrations in vivo. The fluorescence intensity successfully traced the blood glucose concentration fluctuation, indicating our method has potential uses in highly-sensitive and minimally invasive continuous blood glucose monitoring.
    Proceedings of the National Academy of Sciences 10/2010; 107(42):17894-8. · 9.81 Impact Factor
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    ABSTRACT: To clarify the effect of fibroblast growth factor-21 (FGF-21) on islet transplantation, a suboptimal number of islets were transplanted into streptozotocin (STZ)-induced diabetic mice with or without FGF-21 treatment. Three-day treatment with FGF-21 contributed to restoration of normoglycemia by suppressing islet graft loss. The FGF-21-treated mice showed lower glycemic levels despite similar insulin content in the graft than that in untreated mice on day 3, indicating that FGF-21 not only has a cytoprotective effect but also decreases β-cell load by increasing insulin sensitivity. These results suggest that FGF-21 may be useful as a treatment to improve islet engraftment rates in clinical islet transplantation.
    Islets 01/2010; 2(4):247-51. · 1.55 Impact Factor
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    ABSTRACT: In this paper, we present imaging of the physiological cell reaction of stimulus-responsive cells using a new orifice channel chip named the TISSUE-MIMICKING IN VITRO ANALYSIS SYSTEM. The chip enables designated cells treatment using orifice-channels similar to blood vessels, and cell-array like a tissue: cells are along on the blood vessels. These cell handling is an important part in the observation of regulation of cell-functions on stimulus-responsive cells (e.g. pancreas). To study this role, we address to detect cellular stimulation response to designated stimulation using the chip.
    Solid-State Sensors, Actuators and Microsystems Conference, 2009. TRANSDUCERS 2009. International; 07/2009
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    ABSTRACT: We developed a method to prepare size-and shape-controlled islet-cell spheroids. We cultured beta-cell line (MIN6-m9) in PDMS-microwells and enabled to construct their spheroids with the various sizes corresponding to those of the microwells. We demonstrated the geometric analysis of insulin secretion of the cells in the spheroids. We found that these spheroids respond to glucose and subsequently secrete insulin. Also, immunocytochemistry and the real-time live cell imaging of the Ca<sup>2+</sup> oscillation revealed for the first time that the only cells approximately 36 mum apart from the periphery showed higher insulin secretion in the spheroid. This result indicates that our MEMS technique controlling the size and the shape of the spheroids is useful to construct islet-like tissue that functions efficiently and is applicable to transplantation therapy targeted to insulin dependent diabetes mellitus.
    Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009

Publication Stats

1k Citations
480.66 Total Impact Points

Institutions

  • 2010–2014
    • The University of Tokyo
      • Institute of Industrial Science
      Edo, Tōkyō, Japan
  • 2005–2010
    • Kyoto University
      • • Department of Diabetes and Clinical Nutrition
      • • Graduate School of Medicine / Faculty of Medicine
      Kyoto, Kyoto-fu, Japan
  • 2007–2009
    • Baylor Health Care System
      Dallas, Texas, United States
    • Fujita Health University
      • Department of Surgery
      Toyohashi, Aichi-ken, Japan
  • 2001–2009
    • Okayama University
      • Department of Gastroenterological Surgery, Transplant, and Surgical Oncology
      Okayama, Okayama, Japan
    • University of Maryland, Baltimore
      Baltimore, Maryland, United States
  • 2008
    • Nagoya University
      Nagoya, Aichi, Japan