In this study, we developed a novel method for fabricating microwell arrays constructed from alginate gels, and the alginate gel microwells were used for three-dimensional (3D) cell culture. The alginate gel microwells were fabricated on a patterned ITO electrode using alginate gel electrodeposition. Embryonic stem (ES) cells or hepatocellular carcinoma cells (HepG2) were cultured in the alginate gel microwells containing 3T3 cells. During the culture, embryoid bodies (EBs) or HepG2 spheroids were successfully fabricated in the alginate gel microwells. The oxygen consumption of the EBs indicated that they were successfully cultured. Liver-specific gene expressions of the HepG2 spheroids apparently increased by performing 3D co-culture in the microwell arrays with 3T3 cells. These results show that the alginate gel microwells are a useful 3D culture system.
Here we propose a novel electrochemical lithography methodology for fabricating calcium-alginate hydrogels having controlled shapes. We separated the chambers for Ca2+ production and gel formation with alginate with a semipermeable membrane. Ca2+ formed in the production chamber permeated through the membrane to fabricate a gel structure on the membrane in the gel formation chamber. When the calcium-alginate hydrogels were modified with collagen, HepG2 cells proliferated on the hydrogels. These results show that electrochemical hydrogel lithography is useful for cell culture.
A local redox cycling-based electrochemical (LRC-EC) chip device was used to investigate the relationship between cardiomyocyte differentiation from embryonic stem (ES) cells and alkaline phosphatase (ALP) activity. In the LRC-EC chip device, ring-type interdigitated array electrodes were incorporated at n × n measurement points with only 2n bonding pads for external connection. Microwells were also fabricated at each measurement point to trap cell aggregates. To differentiate ES cells into cardiomyocytes, ES cells were three-dimensionally cultured to form simple and cystic embryoid bodies (EBs). ALP activity of these EBs was then detected using the LRC-EC chip device. The electrochemical responses for ALP activity decreased concurrently with the differentiation of ES cells into cardiomyocytes, indicating that an LRC-EC chip device is useful for evaluating cell differentiation.
Cell therapy using human-stem-cell-derived pancreatic beta cells (hSC-bs) is a potential treatment method for type 1 diabetes mellitus (T1D). For therapeutic safety, hSC-bs need encapsulation in grafts that are scalable and retrievable. In this study, we developed a lotus-root-shaped cell-encapsulated construct (LENCON) as a graft that can be retrieved after long-term hSC-b transplantation. This graft had six multicores encapsulating hSC-bs located within 1 mm from the edge. It controlled the recipient blood glucose levels for a long-term, following transplantation in immunodeficient diabetic mice. LENCON xenotransplanted into immunocompetent mice exhibited retrievability and maintained the functionality of hSC-bs for over 1 year after transplantation. We believe that LENCON can contribute to the treatment of T1D through long-term transplantation of hSC-bs and in many other forms of cell therapy.
Human iPSC-derived hepatocytes hold great promise as a cell source for cell therapy and drug screening. However, the culture method for highly-quantified hepatocytes has not yet been established. Herein, we have developed an encapsulation and 3D cultivation method for iPSC-hepatocytes in core-shell hydrogel microfibers (a.k.a. cell fiber). In the fiber-shaped 3D microenvironment consisting of abundant extracellular matrix (ECM), the iPSC-hepatocytes exhibited many hepatic characteristics, including the albumin secretion, and the expression of the hepatic marker genes (ALB, HNF4α, ASGPR1, CYP2C19, and CYP3A4). Furthermore, we found that the fibers were mechanically stable and can be applicable to hepatocyte transplantation. Three days after transplantation of the microfibers into the abdominal cavity of immunodeficient mice, human albumin was detected in the peripheral blood of the transplanted mice. These results indicate that the iPSC-hepatocyte fibers are promising either as in vitro models for drug screening or as implantation grafts to treat liver failure.
In this study, a useful method was developed to fabricate array patterns of microparticles not on electrode surfaces, but on arbitrary surfaces, using negative-dielectrophoresis (n-DEP). First, electrodes were designed and electric field simulations were performed to manipulate microparticles toward target areas. Based on the simulation results, multilayered array and grid (MLAG) electrodes, consisting of array electrodes surrounded by insulated regions and a grid electrode, were fabricated for the formation of localized, non-uniform electric fields. The MLAG electrode was mounted to a target substrate in a face-to-face configuration with a spacer. When an AC voltage (4.60 Vrms and 1 MHz) was applied to the MLAG electrode, array patterns of 6 and 20 microm diameter microparticles were rapidly fabricated on the target substrate with ease. The results suggest that MLAG electrodes can be widely applied for the fabrication of biochips including cell arrays.
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