- [Show abstract] [Hide abstract] ABSTRACT: This article confirmed that the sensor retains its measurement capability for more than 150 days in a saline solution. In addition, an optimization of the sensor structure for obtaining an improved response time was carried out. A response time as short as that of the conventional self-monitoring of blood glucose (SMBG) technology was obtained with the optimized sensor structure.
- [Show abstract] [Hide abstract] ABSTRACT: Objectives: Because therapeutic options for severe diabetes are currently limited, there is a continuing need for new therapeutic strategies, especially in the field of regenerative medicine. Collaborative efforts across the fields of tissue engineering technology and islet biology may be able to create functionally engineered islets capable of restoring endocrine function in patients with insulin-dependent diabetes. Methods: This engineered scaffold was seeded with isolated primary porcine islets via the pancreatic duct using a multi-step infusion technique. Endocrine function of perfusion-cultured islets in the native scaffold was analyzed by immunohistochemical staining of insulin and glucagon as well as by the insulin stimulation test. Results: The pancreas in this large animal could be uniformly decellularized by perfusion with trypsin and TritonX-100 via the pancreatic duct, as shown by positive staining of extracellular matrix (ECM) components. These scaffolds derived from porcine pancreas were able to maintain the cellular integrity of islets that had repopulated the parenchymal space, which is fundamental for the restoration of endocrine function. Insulin release up to four days after islet infusion was maintained. Conclusions: This scaffold from a large animal maintained islet survival and function in the short-term, retaining the cells as a solid organ in the parenchymal space after infusion through the pancreatic duct. These results suggest that this scaffold is suitable for further fabrication of fully functional bioengineered endocrine pancreases when implanted in vivo. Therefore, it may represent a key improvement in the field of beta-cell replacement therapy. Nonetheless, the facilitation of longer-term islet survival and studies of implantation in vivo is required for successful clinical translation.
- [Show abstract] [Hide abstract] ABSTRACT: On page 548, S. Takeuchi and co-workers demonstrate how adipocyte fibers exhibiting morphologies and functions of native adipose tissues differentiate from adipose derived stem cells encapsulated in hydrogel microfibers using the cell fiber technology. This method allows mature unilocular adipocytes to establish dense cell-cell contacts. Molding of the adipocyte fibers into doll-shaped constructs further demonstrates the versatility of the fibers as microtissues for biological, pharmaceutical, and clinical applications.
- [Show abstract] [Hide abstract] ABSTRACT: Piceatannol is a phytochemical in the seeds of passion fruit that has a hypoglycemic effect when orally administered. To elucidate the contribution of intact and metabolites of piceatannol after gastro-intestinal absorption to hypoglycemic effect, we examined the influence of piceatannol and isorhapontigenin on blood glucose concentrations during fasting and glucose tolerance tests by administering them intravascularly to freely moving healthy rats. We found that intravascularly administered piceatannol reduced the blood glucose concentrations during both fasting and glucose tolerance tests, but isorhapontigenin did not during either of them. Furthermore, we found that piceatannol increased the insulinogenic index during glucose tolerance tests and that piceatannol had no influence on insulin sensitivity by performing hyperinsulinemic euglycemic clamping tests. These results suggest that piceatannol orally intaken may enhance glucose tolerance by the effect of intact piceatannol through enhanced early-phase secretion of insulin. Therefore, oral intake of piceatannol might contribute to proper control of postprandial glycemic excursions in healthy subjects.
- [Show abstract] [Hide abstract] ABSTRACT: Adipose tissue, an active metabolic and endocrine organ mainly composed of unilocular adipocytes, is implicated in various obesity related diseases. Developing morphologically and functionally accurate in vitro models of the adipose tissue is therefore critically important for basic biological studies, drug screening/testing, and clinical implants to advance the understanding and treatment of these diseases. However, current adipose tissue engineering technologies either cannot replicate the unilocular morphologies of mature adipocytes, or lack the ease of monitoring, handling, and scaling up required in the above mentioned applications. This paper presents the differentiation of adipose derived stem cells (ADSCs) to mature adipocytes in highly observable and highly handleable 3D fiber shaped constructs exhibiting morphologies and functions of native adipose tissues. Using the cell fiber technology, ADSCs were encapsulated in hydrogel microfibers, allowed to form into fiber shaped constructs, and differentiated to mature unilocular adipocytes. These adipocyte fibers are observed and maintained for up to 91 d, and secretion of adipose tissue-specific factor, adiponectin, is further confirmed. The handleability of the adipocyte fibers is demonstrated by assembling the adipocyte fibers into doll shaped constructs. Such highly observable, highly handleable, and scalable characteristics of the adipocyte fibers make them suitable for biological studies, high-throughput drug screening/testing, and clinical applications.
- [Show abstract] [Hide abstract] ABSTRACT: An implantable glucose monitoring device based on a CMOS line sensor combined with a glucose-responsive fluorescent hydrogel is developed. An implantable glucose monitoring device with sufficient sensitivity and response time is realised, which is an improvement over the authors' previous proof-of-concept device. A reduction of the sensor size made the device diameter injectable with a commercially available 16-gauge syringe needle. The sensor's performance was confirmed through both in vitro and in vivo experiments.
- [Show abstract] [Hide abstract] ABSTRACT: The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments.
- [Show abstract] [Hide abstract] ABSTRACT: This paper reports the culturing and expansion of mouse induced pluripotent stem cells (iPSCs) in hydrogel core-shell microfibers; the core consists of iPSCs with or without extracellular matrix (ECM) proteins, and the shell is composed of calcium alginate. We revealed that mouse iPSCs cultured in the micro-scale space with ECM proteins sustain their pluriotency efficiently. This 3D culture system may be a useful tool to expand iPSCs for clinical use.
- [Show abstract] [Hide abstract] ABSTRACT: This paper describes the construction and differentiation of human adipose-derived stem cell (ADSC) fibers into the adipocyte lineage for breast reconstruction. Human ADSCs were encapsulated into the core region of hydrogel core-shell fibers by the cell fiber technology , induced for adipogenic differentiation, and maintained for over 2 months. After adipogenic induction, accumulation of lipid droplets of significant size was observed in the cells, and viability assay showed that most of the cells were alive. These findings suggest the use of ADSC fibers as a promising approach for breast reconstruction.
- [Show abstract] [Hide abstract] ABSTRACT: This paper describes a small sized balloon pump for providing liquid in low flow rate without a driving source. The balloon pump is composed of a balloon tank and a microfluidic valve. The balloon tank can work as a reservoir to store liquid and an actuator to pump liquid. By connecting the microfluidic valve to the balloon tank, we achieved extremely low flow rates of the liquid. Therefore, our balloon pump will be applicable to implantable pumps for the continuous drug supply in low flow rates without batteries.
- [Show abstract] [Hide abstract] 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. (C) 2014 Optical Society of America
- [Show abstract] [Hide abstract] ABSTRACT: To provide a fluorescent hydrogel having superior detectability of saccharides such as glucose and minimal invasiveness, a method for producing the same, and a sensor for measuring saccharides using the same. A florescent hydrogel having a structure represented by the following chemical formula 1, a method for producing the same, and a sensor for measuring saccharides using the same.
- [Show abstract] [Hide abstract] 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.
- [Show abstract] [Hide abstract] ABSTRACT: After producing α1-3-galactosyltransferase knockout (GKO) 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-galactosidase now showed a clear antigenicity to human serum. In this study, N-glycans were isolated from both APIs and human islets. Their structures were then analyzed by a mapping technique based on their high-performance liquid chromatography elution positions and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometric 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, and the API glycans were comprised of 11 neutral, 8 mono-sialyl, 3 di-sialyl, 2 mono-sulfated, 3 mono-sialyl-mono-sulfated and 1 di-sulfated glycans. 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 9 of these 12 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.
- [Show abstract] [Hide abstract] ABSTRACT: This conference proceeding describes a balloon injector composed of a balloon actuator and a microfluidic regulator to achieve an implantable passive drug pump. The balloon actuator can work as a driving source to pump liquid. By connecting the leaky valve to the balloon actuator, we achieved smaller and more constant flow rate of the liquid. Therefore, our system will be applicable to implantable passive pumps for the constant supply of liquid with small flow rate without batteries.
- [Show abstract] [Hide abstract] ABSTRACT: The number of patients with diabetes is on an increasing trend, thus leading to the belief that diabetes will be the largest medical problem of the 21st century. Islet transplantation can improve glycometabolic control in patients with type 1 diabetes. We studied the viability of Rho-associated protein kinase (ROCK) inhibitor Y-27632 in a culture system in vitro on freshly isolated rat islets. Islet isolation was conducted on a Lewis rat, and studies of culture solutions were split into two groups, one group using ROCK inhibitor Y-27632, and another without. On the seventh day of culture, we evaluated the differences for the cell morphology, viability, and insulin secretion. The Y-27632 group maintained form better than the group without Y-27632. With strong expression of Bcl-2 observed with the Y-27632 group, and expression suppressed with Bax, inhibition of apoptosis by Y-27632 was confirmed. The Y-27632 group predominantly secreted insulin. For islet transplantation, Y-27632 inhibited cell apoptosis in a graft and was also effective in promoting insulin secretion. We were able to confirm effective morphological and functional culture maintenance by separating islets from a rat and adding ROCK inhibitor Y-27632 to the medium.
- [Show abstract] [Hide abstract] 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.
Tokyo International University
The University of Tokyo白山, Tōkyō, Japan
Fujita Health UniversityNagoya, Aichi, Japan
Okayama UniversityOkayama, Okayama, Japan