Riho Gojo

Metre-long cell-laden microfibres exhibit tissue morphologies and functions

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.

Biomolecular-Motor-Based Nano- or Microscale Particle Translocations on DNA Microarrays

We aimed to create autonomous on-chip systems that perform targeted translocations of nano- or microscale particles in parallel using machinery that mimics biological systems. By exploiting biomolecular-motor-based motility and DNA hybridization, we demonstrate that single-stranded DNA-labeled microtubules gliding on kinesin-coated surfaces acted as cargo translocators and that single-stranded DNA-labeled cargoes were loaded/unloaded onto/from gliding microtubules at micropatterned loading/unloading sites specified by DNA base sequences. Our results will help to create autonomous molecular sorters and sensors.

Biomolecular-motor-based autonomous delivery of lipid vesicles as nano- or microscale reactors on a chip

We aimed to create an autonomous on-chip system that performs targeted delivery of lipid vesicles (liposomes) as nano- or microscale reactors using machinery from biological systems. Reactor-liposomes would be ideal model cargoes to realize biomolecular-motor-based biochemical analysis chips; however, there are no existing systems that enable targeted delivery of cargo-liposomes in an autonomous manner. By exploiting biomolecular-motor-based motility and DNA hybridization, we demonstrate that single-stranded DNA (ssDNA)-labeled microtubules (MTs), gliding on kinesin-coated surfaces, acted as cargo transporters and that ssDNA-labeled cargo-liposomes were loaded/unloaded onto/from gliding MTs without bursting at loading reservoirs/micropatterned unloading sites specified by DNA base sequences. Our results contribute to the development of an alternative strategy to pressure-driven or electrokinetic flow-based microfluidic devices.

Core-shell gel wires for the construction of large area heterogeneous structures with biomaterials

This paper describes core-shell hydrogel wires for constructing 3D heterogeneous hydrogel microstructures containing biomaterials. A core hydrogel layer contains biomaterials such as cells, and a shell hydrogel layer covers the core to realize a mechanically-robust hydrogel wire. Using this core-shell gel wires, we demonstrate a woven sheet with heterogeneous gel wires by using our stereolithographically-made weaving machine. We also fabricate a reeled-up tube-like cell-containing structure by a glass tube spindle, inspired by tools from fiber industry. We show that our core-shell gel wires and weaving methods are powerful approach to arrange heterogeneous biomaterials in three dimensions.

Living cell fabric

This paper describes a centimeter-scale living cell fabric made of cell-containing core-shell hydrogel fibers, “cell fiber.” We improved core-shell fiber applicable to various types of cells, and precisely characterized their biofunctions and mechanical properties. Using these cell fibers, we demonstrate a centimeter-scale living cell fabric woven by our micro weaving machine. We believe that our weaving approach using cell fibers would be a powerful method for constructing large-scale 3D-patterned functional tissues.

Biomolecular motor-based cargo transporters with loading/unloading mechanisms on a micro-patterned DNA array

This paper describes research in creating autonomous cargo transporters that load, transport, and unload cargo molecules using the machinery in living cells. By exploiting biomolecular motor-based motility and DNA hybridization, we constructed autonomous cargo transporters and demonstrated that kinesin-driven microtubules can selectively load and transport cargoes toward micro- patterned DNA spots designed to be unloading sites and selectively unload the transported cargoes at the DNA spots specified by particular DNA base sequences. These autonomous operations may help create highly miniaturized on-chip-systems such as molecular sorters and sensors, and may also provide an alternative technology to pressure-driven or electrokinetic flow-based microfluidic devices.

Microfluidic handling of hydrogel microfibers

This paper describes a handling method of thin (~200 μm in diameter), long (>;meter) and fragile (breaking point: ~2 μN) hydrogel microfibers in liquid. By using fluid flow and thin capillary, the hydrogel fibers can be manipulated, clamped and cut without damaging and entangling the hydrogel microfibers (we termed “microfluidic handling”). This microfluidic handling technique enables us to construct a mechanical weaving machine for cell-encapsulating hydrogel microfibers, resulting the construction of centimeter-scale woven 3D cellular structures. In addition, we demonstrated computer-controlled automatic handling of the hydrogel microfibers, indicating that the microfluidic handling would be a fundamental technique for rapid and reliable handling of fragile hydrogel microfibers containing various types of functional materials such as cells, bacteria, proteins and nanofibers.

A Flexible Regeneration Microelectrode with Cell-Growth Guidance

In this study we fabricate a cell-guide on a thin disc-shaped probe with numerous microholes to be implanted between the severed stumps of axons; the cell-guide directs the regenerating axons though the holes in our probe (Fig. 1(a)). Since cell growth is greatly influenced by the topography of the substrate [1-3] we design a SU8 microfluidic cell-guide with a particular shape (Fig. 1(b)) to prevent the random spreading of cells by directing cell growth through the holes. This guide may reduce the chance of short-circuits of the probe by cells that span two different electrodes. Furthermore, as the cells are directed to grow through the holes, we can measure their electrical potential with gold electrodes that we micro-fabricate.

Optimizing the diameter of holes for flexible regeneration microelectrode

In this study, we suggest a new guideline for regeneration microelectrode to be implanted between the severed stumps of peripheral nerves, the microelectrode designed particularly for connecting the signal line of an artificial hand directly to the nerve system. The nerve regeneration microelectrode is an interface device expected to realize a BMI (brain-machine interface).